Engineering geological maps; a guide to their preparation; Earth

Earth sciences 15Earth sciences 15

Titles in this series:

1. The seismicity of the earth, 1953-1965/La séismicité du globe.1953-1965by/par J. P. Rothé

2. Gondwana stratigraphy. IUGS Symposium, Buenos Aires.1-15 October 1967/La estratigrafía del Gondwana. Coloquio dela UICG, Buenos Aires, 1-15 de octubre de 1967

3. Mineral map of Africa. Explanatory note/Carte minérale del'Afrique. Notice explicative. 1/10000000

4. Cartes tectonique internationale de l'Afrique. Notice explicative/International tectonic map of Africa. Explanatory note.1/5000000

5. Notes on geomagnetic observatory and survey practice,by K.A. Wienert

5. Méthodes d'observation et de prospection géomagnétiques,par K.A. Wienert

6. Tectonique de l'Afrique/Tectonics of Africa7. Geology of saline deposits. Proceedings of the Hanover

Symposium, 15-21 May 1968. Edited by G. Richter-Bernburg/Géologie des dépôts salins. Actes du colloque de Hanovre,15-21 mai 1968. Texte mis au point par G. Richter-Bernburg

8. The surveillance and prediction of volcanic activity.A review of methods and techniques

9. Genesis of Precambrian iron and manganese deposits.Proceedings of the Kiev Symposium, 20-25 August 1970/Genèse des formations précambriennes de fer et de manganèse.Actes du colloque de Kiev, 20-25 août 1970

10. Carte géologique internationale de l'Europe et des régionsriveraines de la Méditerranée. Notice explicative/Internationalgeological map of Europe and the Mediterranean region.Explanatory note. 1/5000000[Edition multilingue: français, anglais, allemand, espagnol,italien, russe]

1 1 . Geological map of Asia and the Far East.1/5000000. Second edition. Explanatory note

11. Carte géologique de l'Asie et de l'Extrême-Orient.1/5000000. Deuxième édition. Notice explicative

12. Geothermal energy. Review of research. Edited byH. Christopher Armstead

1 3. Carte tectonique de l'Europe et des régions avoisinantes.1/2500000. Notice explicative/Tectonic map of Europe andadjacent areas. 1/2500000. Explanatory note

14. Carte tectonique du système carpato-balkanique.1/1 000000. Notice explicative/Tectonic map of theCarpathian-Balkan system. 1/1000000. Explanatory note

1 5. Engineering geological maps. A guide to their preparation

1 5. Guide pour la préparation des cartes géotechniques

Titles in this series:

1. The seismicity of the earth, 1953-1965/La séismicité du globe.1953-1965by/par J. P. Rothé

2. Gondwana stratigraphy. IUGS Symposium, Buenos Aires.1-15 October 1967/La estratigrafía del Gondwana. Coloquio dela UICG, Buenos Aires, 1-15 de octubre de 1967

3. Mineral map of Africa. Explanatory note/Carte minérale del'Afrique. Notice explicative. 1/10000000

4. Cartes tectonique internationale de l'Afrique. Notice explicative/International tectonic map of Africa. Explanatory note.1/5000000

5. Notes on geomagnetic observatory and survey practice,by K.A. Wienert

5. Méthodes d'observation et de prospection géomagnétiques,par K.A. Wienert

6. Tectonique de l'Afrique/Tectonics of Africa7. Geology of saline deposits. Proceedings of the Hanover

Symposium, 15-21 May 1968. Edited by G. Richter-Bernburg/Géologie des dépôts salins. Actes du colloque de Hanovre,15-21 mai 1968. Texte mis au point par G. Richter-Bernburg

8. The surveillance and prediction of volcanic activity.A review of methods and techniques

9. Genesis of Precambrian iron and manganese deposits.Proceedings of the Kiev Symposium, 20-25 August 1970/Genèse des formations précambriennes de fer et de manganèse.Actes du colloque de Kiev, 20-25 août 1970

10. Carte géologique internationale de l'Europe et des régionsriveraines de la Méditerranée. Notice explicative/Internationalgeological map of Europe and the Mediterranean region.Explanatory note. 1/5000000[Edition multilingue: français, anglais, allemand, espagnol,italien, russe]

1 1 . Geological map of Asia and the Far East.1/5000000. Second edition. Explanatory note

11. Carte géologique de l'Asie et de l'Extrême-Orient.1/5000000. Deuxième édition. Notice explicative

12. Geothermal energy. Review of research. Edited byH. Christopher Armstead

1 3. Carte tectonique de l'Europe et des régions avoisinantes.1/2500000. Notice explicative/Tectonic map of Europe andadjacent areas. 1/2500000. Explanatory note

14. Carte tectonique du système carpato-balkanique.1/1 000000. Notice explicative/Tectonic map of theCarpathian-Balkan system. 1/1000000. Explanatory note

1 5. Engineering geological maps. A guide to their preparation

1 5. Guide pour la préparation des cartes géotechniques

Engineeringgeological maps

A guide to their preparation

Prepared by the Commission onEngineering Geological Mapsof the International Associationof Engineering Geology

The Unesco Press Paris 1976

Engineeringgeological maps

A guide to their preparation

Prepared by the Commission onEngineering Geological Mapsof the International Associationof Engineering Geology

The Unesco Press Paris 1976

The designations employed and the presentation of the materialin this publication do not imply the expression of any opinionwhatsoever on the part of the Unesco Secretariat concerning thelegal status of any country or territory, or of its authorities, orconcerning the delimitations of the frontiers of any country orterritory.

Published by The Unesco Press7 Place de Fontenoy, 75700 ParisPrinted by Imprimeries Réunies, Lausanne

ISBN 92-3-101243-6French edition 92-3-201243-X

O Unesco I97S Printed m Switzerland

The designations employed and the presentation of the materialin this publication do not imply the expression of any opinionwhatsoever on the part of the Unesco Secretariat concerning thelegal status of any country or territory, or of its authorities, orconcerning the delimitations of the frontiers of any country orterritory.

Published by The Unesco Press7 Place de Fontenoy, 75700 ParisPrinted by Imprimeries Réunies, Lausanne

ISBN 92-3-101243-6French edition 92-3-201243-X

O Unesco I97S Printed m Switzerland

Preface

With a view to promoting global and regional synthesis ofknowledge and the general advancement of geologicalscience, and to providing the scientific basis for a better un¬

derstanding of the world's mineral and land resources, Unescohas, for many years, been concerned with the preparationand publication of small-scale geological maps of variouskinds. The present booklet is devoted to a particular aspectof this programme, namely engineering geological mapping.

The purpose of such maps is to show the distribution ofspecific geological phenomena and characteristics of rocksand soils affecting the engineering use of different terrains.The ever-growing demand for such maps has revealed theneed for a standardization of principles, systems andmethods. This is an urgent but at the same time a difficultproblem which can best be solved through international co¬

operation.The present guidebook, prepared for Unesco by the

Commission on Engineering Geological Maps of the Inter

national Association of Engineering Geology, summarizesthe views of an international commission of experts and in¬

corporates experience from various countries in which en¬

gineering geological mapping is already undertaken at anadvanced level. This book does not pretend to give detailedinstructions for mapping, but rather to be a synthesis ofpresent-day experience in this field. The views expressed arethose of the authors and are not necessarily those of Unesco.

Unesco wishes to express its gratitude to all those whocollaborated in the preparation of this text, and especially toProfessor M. Arnould, President of the International Asso¬

ciation of Engineering Geology, to Professor M. Matula ofthe Comenius University, Bratislava, President of theCommission on Engineering Geological Maps of the Inter¬national Association of Engineering Geology, and toProfessor W. R. Dearman of the University of Newcastleupon Tyne who kindly edited the text.

Preface

With a view to promoting global and regional synthesis ofknowledge and the general advancement of geologicalscience, and to providing the scientific basis for a better un¬

derstanding of the world's mineral and land resources, Unescohas, for many years, been concerned with the preparationand publication of small-scale geological maps of variouskinds. The present booklet is devoted to a particular aspectof this programme, namely engineering geological mapping.

The purpose of such maps is to show the distribution ofspecific geological phenomena and characteristics of rocksand soils affecting the engineering use of different terrains.The ever-growing demand for such maps has revealed theneed for a standardization of principles, systems andmethods. This is an urgent but at the same time a difficultproblem which can best be solved through international co¬

operation.The present guidebook, prepared for Unesco by the

Commission on Engineering Geological Maps of the Inter

national Association of Engineering Geology, summarizesthe views of an international commission of experts and in¬

corporates experience from various countries in which en¬

gineering geological mapping is already undertaken at anadvanced level. This book does not pretend to give detailedinstructions for mapping, but rather to be a synthesis ofpresent-day experience in this field. The views expressed arethose of the authors and are not necessarily those of Unesco.

Unesco wishes to express its gratitude to all those whocollaborated in the preparation of this text, and especially toProfessor M. Arnould, President of the International Asso¬

ciation of Engineering Geology, to Professor M. Matula ofthe Comenius University, Bratislava, President of theCommission on Engineering Geological Maps of the Inter¬national Association of Engineering Geology, and toProfessor W. R. Dearman of the University of Newcastleupon Tyne who kindly edited the text.

Contents

1 Introduction 9

2 Principles 1 1

2.1 Introduction 11

2.2 Definition of an engineering geological map 1 1

2.3 Classification of engineering geological maps 12

2.4 Principles of classification of rocks and soils forengineering geological mapping 12

2.5 Hydrogeological conditions 13

2.6 Geomorphological conditions 13

2.7 Evaluation of geodynamic phenomena 13

2.8 Principles of engineering geological zoning 14

2.9 General principles 15

2.10 References 15

3 Techniques for acquiring and interpreting data 17

3.1

3.2

3.3

3.4

3.53.6

Introduction 17

General methods of geological mapping 17

3.2. 1 Preparation of the topographic base map 17

3.2.2 Acquisition of geological information 17

Special requirements for engineering geologicalmapping 17

3.3.1 Engineering geological description of rocksand soils 17

Mapping of rocks and soils for engineeringpurposes 1 8

Mapping hydrogeological conditions 18

Mapping the results of geodynamicprocesses 1 8

Special techniques for engineering geological map¬ping 19

Photogeology 19

Geophysical methods 19

Boring and sampling techniques 19

Laboratory and in situ testing 22Analysis and interpretation of data 22References 22

3.3.2

3.3.33.3.4

3.4.13.4.23.4.33.4.4

4.4 Interpretative geological maps 25

4.5 Three-dimensional representation on maps 25

4.6 Engineering geological cross-sections 25

4.7 Documentation maps 25

4.8 Explanation and legend 26

4.9 Reference 26

5 Examples of engineering geological maps 275.1 Introduction 275.2 Examples of multipurpose engineering geological

maps 285.2.1 Multipurpose analytical maps 285.2.2 Multipurpose comprehensive maps 32

5.3 Examples of special purpose engineering geologicalmaps 485.3.1 Special purpose analytical maps 48

5.3.2 Special purpose comprehensive maps 525.4 Interpretative geological maps 64

5.4.1 Interpretative geological medium-scalemap 645.4.2 Interpretative geological large-scale map 68


6 Layout of descriptive memoir 72

7 Glossary 73

7.1 Introduction 73

7.2 Definitions of terms used in the text 73

7.3 References 76

Select bibliography 77

8.1 Introduction 77

8.2 Engineering geological mapping . .

8.3 Published engineering geological maps77

78

9 Acknowledgements 79

4 Presentation of data on engineering geological maps 23

4. 1 Introduction 234.2 Multipurpose maps 23

4.2.1 Analytical multipurpose maps 23

4.2.2 Comprehensive multipurpose maps 23

4.3 Special purpose maps 244.3.1 Analytical special purpose maps 25

4.3.2 Comprehensive special purpose maps 25

Contents

1 Introduction 9

2 Principles 1 1

2.1 Introduction 11

2.2 Definition of an engineering geological map 1 1

2.3 Classification of engineering geological maps 12

2.4 Principles of classification of rocks and soils forengineering geological mapping 12

2.5 Hydrogeological conditions 13

2.6 Geomorphological conditions 13

2.7 Evaluation of geodynamic phenomena 13

2.8 Principles of engineering geological zoning 14

2.9 General principles 15

2.10 References 15

3 Techniques for acquiring and interpreting data 17

3.1

3.2

3.3

3.4

3.53.6

Introduction 17

General methods of geological mapping 17

3.2. 1 Preparation of the topographic base map 17

3.2.2 Acquisition of geological information 17

Special requirements for engineering geologicalmapping 17

3.3.1 Engineering geological description of rocksand soils 17

Mapping of rocks and soils for engineeringpurposes 1 8

Mapping hydrogeological conditions 18

Mapping the results of geodynamicprocesses 1 8

Special techniques for engineering geological map¬ping 19

Photogeology 19

Geophysical methods 19

Boring and sampling techniques 19

Laboratory and in situ testing 22Analysis and interpretation of data 22References 22

3.3.2

3.3.33.3.4

3.4.13.4.23.4.33.4.4

4.4 Interpretative geological maps 25

4.5 Three-dimensional representation on maps 25

4.6 Engineering geological cross-sections 25


4.8 Explanation and legend 26

4.9 Reference 26

5 Examples of engineering geological maps 275.1 Introduction 275.2 Examples of multipurpose engineering geological

maps 285.2.1 Multipurpose analytical maps 285.2.2 Multipurpose comprehensive maps 32

5.3 Examples of special purpose engineering geologicalmaps 485.3.1 Special purpose analytical maps 48

5.3.2 Special purpose comprehensive maps 525.4 Interpretative geological maps 64

5.4.1 Interpretative geological medium-scalemap 645.4.2 Interpretative geological large-scale map 68


6 Layout of descriptive memoir 72

7 Glossary 73

7.1 Introduction 73

7.2 Definitions of terms used in the text 73

7.3 References 76


8.1 Introduction 77

8.2 Engineering geological mapping . .

8.3 Published engineering geological maps77

78

9 Acknowledgements 79

4 Presentation of data on engineering geological maps 23

4. 1 Introduction 234.2 Multipurpose maps 23

4.2.1 Analytical multipurpose maps 23

4.2.2 Comprehensive multipurpose maps 23

4.3 Special purpose maps 244.3.1 Analytical special purpose maps 25

4.3.2 Comprehensive special purpose maps 25

Introduction i

Engineering geological mapping began to be developed withthe first steps towards co-operation between geologists andengineers in the building of the larger engineering workssuch as tunnels, dams and railways. The first maps hardlydiffered from current stratigraphie-lithologie and tectonic-structural maps. Gradually, increasing demands by engineersfor more and more quantitative geological data led to theappearance first in explanatory texts, then in enlarged maplegends and finally on the actual geological maps, of morespecific information on the technical aspects of geologicalphenomena and their engineering interpretation. Up to thepresent such interpretative maps are those in current use andmay even be called engineering geological maps.

Developments in the theory and practice of mapping inengineering geology, however, have shown that such techni¬cal or interpretative or derived maps are not what true en¬

gineering geological maps should be.The task of engineering geology is to provide engineers,

planners and designers with such information as will helpthem to create engineering structures and to develop thecountry in the best possible harmony with the geologicalenvironment. Without harmony, every civil engineeringwork, and these are mainly dams, tunnels, highways, cities,industrial agglomerations and big open pit mines, interferesoften to a considerable extent with the dynamic equilibriumof the geological environment. This may result in detrimentalconsequences which can affect not only the economy anddurability but also the safety of the works.

The geological environment is a very complex multi-component dynamic system which cannot be studied in itsentirety in connexion with construction works or other en¬

gineering activities. Using the method of model analysis asimplified picture has to be created of this system comprisingonly those components of the geologic environment whichfrom the point of view of engineering geology are of a deci¬sive significance: namely the distribution and properties ofrocks and soils, groundwater, characteristics of the relief andpresent geodynamic processes. An engineering geologicalmap, showing the distribution and spatial relationships ofthese basic components, can reflect the history as well as thedynamics of the development of engineering geological condi¬tions; it enables a prognosis to be made of the influence ofthe environment on the engineering works, as well as topredict in which way the works will interfere with the envi¬ronment. It is in a key position, and of immeasurable impor¬tance in the system of engineering geological information.

Naturally, such maps cannot replace a detailed investigationof a construction site, but will help both in the rationaldesign of a site investigation and in the interpretation of theresults.

Maps can be prepared for the most varied purposes: forexample, in land-use planning for complex utilization anddevelopment of regions of varied character (including scarce¬

ly mastered areas with permafrost, semi-arid climate, seismichazard) and of differing extents varying from whole state-territories to individual city districts. They can serve for cer¬

tain specific purposes only, or may present a broader, multi¬purpose view necessary for solving more general problems;they can serve as first steps in planning, as well as in the finalstages of designing urban, industrial, transport, hydrotechni-cal or other constructions. Dependent upon purpose, mapsmay be of varied extent, scale and detail; they can havedifferent contents and a varied choice of mapping attributes,as well as different aspects of their evaluation.

In all this variety and individuality, engineering geologi¬cal maps as with stratigraphical-lithological and tectonicmaps must embody certain conventions, a common classifi¬cation as well as common principles, and a certain degree ofstandardization. The achievement of this is a considerableand very difficult task in international co-operation betweenengineering geologists.

At recent international congresses and symposia, and inthe professional literature a wide ranging discussion hastaken place on the problem of the principles of engineeringgeological mapping. These discussions embrace such topicsas: what is an engineering geological map? What are itsbasic concepts and methodological background? How mayvarious kinds of maps be classified according to their pur¬pose, scale and content? What basic criteria should be usedin the classification of rocks (as well as other phenomena)and territorial units on engineering geological maps? Whatare the problems of collection, interpretation and representa¬tion of engineering geological information? How can com¬

puters be used in the preparation of maps and what is thefuture of engineering geological mapping? What is the likeli¬hood of international co-operation in standardization, termi¬nology and in exchange of experience?

A confirmation of the importance of mapping and ofthe necessity of international co-operation towards its subse¬

quent development was given when the General Assembly ofthe International Association of Engineering Geology(IAEG) established in 1968 as its first commission the

Introduction i

Engineering geological mapping began to be developed withthe first steps towards co-operation between geologists andengineers in the building of the larger engineering workssuch as tunnels, dams and railways. The first maps hardlydiffered from current stratigraphie-lithologie and tectonic-structural maps. Gradually, increasing demands by engineersfor more and more quantitative geological data led to theappearance first in explanatory texts, then in enlarged maplegends and finally on the actual geological maps, of morespecific information on the technical aspects of geologicalphenomena and their engineering interpretation. Up to thepresent such interpretative maps are those in current use andmay even be called engineering geological maps.

Developments in the theory and practice of mapping inengineering geology, however, have shown that such techni¬cal or interpretative or derived maps are not what true en¬

gineering geological maps should be.The task of engineering geology is to provide engineers,

planners and designers with such information as will helpthem to create engineering structures and to develop thecountry in the best possible harmony with the geologicalenvironment. Without harmony, every civil engineeringwork, and these are mainly dams, tunnels, highways, cities,industrial agglomerations and big open pit mines, interferesoften to a considerable extent with the dynamic equilibriumof the geological environment. This may result in detrimentalconsequences which can affect not only the economy anddurability but also the safety of the works.

The geological environment is a very complex multi-component dynamic system which cannot be studied in itsentirety in connexion with construction works or other en¬

gineering activities. Using the method of model analysis asimplified picture has to be created of this system comprisingonly those components of the geologic environment whichfrom the point of view of engineering geology are of a deci¬sive significance: namely the distribution and properties ofrocks and soils, groundwater, characteristics of the relief andpresent geodynamic processes. An engineering geologicalmap, showing the distribution and spatial relationships ofthese basic components, can reflect the history as well as thedynamics of the development of engineering geological condi¬tions; it enables a prognosis to be made of the influence ofthe environment on the engineering works, as well as topredict in which way the works will interfere with the envi¬ronment. It is in a key position, and of immeasurable impor¬tance in the system of engineering geological information.

Naturally, such maps cannot replace a detailed investigationof a construction site, but will help both in the rationaldesign of a site investigation and in the interpretation of theresults.

Maps can be prepared for the most varied purposes: forexample, in land-use planning for complex utilization anddevelopment of regions of varied character (including scarce¬

ly mastered areas with permafrost, semi-arid climate, seismichazard) and of differing extents varying from whole state-territories to individual city districts. They can serve for cer¬

tain specific purposes only, or may present a broader, multi¬purpose view necessary for solving more general problems;they can serve as first steps in planning, as well as in the finalstages of designing urban, industrial, transport, hydrotechni-cal or other constructions. Dependent upon purpose, mapsmay be of varied extent, scale and detail; they can havedifferent contents and a varied choice of mapping attributes,as well as different aspects of their evaluation.

In all this variety and individuality, engineering geologi¬cal maps as with stratigraphical-lithological and tectonicmaps must embody certain conventions, a common classifi¬cation as well as common principles, and a certain degree ofstandardization. The achievement of this is a considerableand very difficult task in international co-operation betweenengineering geologists.

At recent international congresses and symposia, and inthe professional literature a wide ranging discussion hastaken place on the problem of the principles of engineeringgeological mapping. These discussions embrace such topicsas: what is an engineering geological map? What are itsbasic concepts and methodological background? How mayvarious kinds of maps be classified according to their pur¬pose, scale and content? What basic criteria should be usedin the classification of rocks (as well as other phenomena)and territorial units on engineering geological maps? Whatare the problems of collection, interpretation and representa¬tion of engineering geological information? How can com¬

puters be used in the preparation of maps and what is thefuture of engineering geological mapping? What is the likeli¬hood of international co-operation in standardization, termi¬nology and in exchange of experience?

A confirmation of the importance of mapping and ofthe necessity of international co-operation towards its subse¬

quent development was given when the General Assembly ofthe International Association of Engineering Geology(IAEG) established in 1968 as its first commission the

Engineering geological maps

Working Group on Engineering Geological Mapping. Thetask of this commission was determined as : (a) to make clearthe present situation in engineering geological mapping ; (b) toanalyse the various types of maps called engineering geologi¬cal maps, or maps which are to serve for building, construc¬tion and land-use planning ; (c) to outline the trends for thefuture development of engineering geological cartographyand to present general recommendations on the informationto be provided by a complex engineering geological map;and (d) to contribute to international exchange of informa¬tion on this subject.

After the publication of reports on the present stage ofengineering geological mapping in various parts of the world{IAEG Bulletin, No. 3, 4), the presentation of this brief guide¬book is the first accomplishment of the commission in re¬

sponse to its stated aims.The text is in four main chapters. A discussion of the

principles of engineering geological mapping involves thedefinition and classification of engineering geological maps,the classification of rocks and soils, consideration of hydro-geological and geomorphological conditions, and the evalua¬tion of geodynamic phenomena. This is followed by a

description of the techniques which may be adopted foracquiring and interpreting data. After a brief reference to theusual methods ofgeological mapping, the special requirementsand techniques of engineering geological mapping are dealtwith. Finally the question of the presentation of data onengineering geological maps and the layout of a descriptivememoir are considered.

This guidebook sets out to answer such questions as

'What is an engineering geological map?' 'How is an en¬

gineering map made?' and 'How is engineering geologicalinformation presented on such a map?'. Future efforts of theIAEG Commission on Engineering Geological Maps will be

devoted, among other things, to the techniques of engineeringgeological mapping and the amplification of the views set outin this guidebook. A very important part of future work willbe an attempt at international co-operation in the selectionand adoption of an agreed list of standard symbols for useon engineering geological maps.

The commission members realize that this guidebook isnot an exhaustive treatment of the subject, and hope thatmore complete versions may be prepared in the future. Anycomments and suggestions that would be of assistance inpreparing future guides to engineering geological mappingwould be greatly appreciated.

Members of the IAEG commission who have taken partin the preparation of this guide are :

Professor Milan Matula (Chairman), Department of En¬gineering Geology and Hydrogeology, Comenius Universi¬ty, Gottwaldo nam. 2, Bratislava (Czechoslovakia).

Professor W. R. Dearman (Editor), Department of Geology,Engineering Geology Unit, University of Newcastle-upon-Tyne (United Kingdom).

Professor G. A. Golodkovskaja, Geological Faculty, Mos-kovskij Universitet, Moskva 117234 (U.S.S.R.).

Professor Ing. M. Janjic, 1 100 Beograd, Tolstojeva 5 (Yugos¬lavia) .

Dr A. Pahl, Bundesanstalt für Geowissenschaften und Roh¬stoffe, 3 Hannover, Postfach 230153 (Federal Republic ofGermany).

A. Peter, Service Géologique Régional Massif Central,22 Avenue de Lempdes, 63800 Cournon d'Auvergne(France).

Mrs Dorothy H. Radbruch-Hall (Secretary), United StatesGeological Survey, 345 Middlefield Road, Menlo Park,CA 94025 (United States of America).

10


Working Group on Engineering Geological Mapping. Thetask of this commission was determined as : (a) to make clearthe present situation in engineering geological mapping ; (b) toanalyse the various types of maps called engineering geologi¬cal maps, or maps which are to serve for building, construc¬tion and land-use planning ; (c) to outline the trends for thefuture development of engineering geological cartographyand to present general recommendations on the informationto be provided by a complex engineering geological map;and (d) to contribute to international exchange of informa¬tion on this subject.

After the publication of reports on the present stage ofengineering geological mapping in various parts of the world{IAEG Bulletin, No. 3, 4), the presentation of this brief guide¬book is the first accomplishment of the commission in re¬

sponse to its stated aims.The text is in four main chapters. A discussion of the

principles of engineering geological mapping involves thedefinition and classification of engineering geological maps,the classification of rocks and soils, consideration of hydro-geological and geomorphological conditions, and the evalua¬tion of geodynamic phenomena. This is followed by a

description of the techniques which may be adopted foracquiring and interpreting data. After a brief reference to theusual methods ofgeological mapping, the special requirementsand techniques of engineering geological mapping are dealtwith. Finally the question of the presentation of data onengineering geological maps and the layout of a descriptivememoir are considered.

This guidebook sets out to answer such questions as

'What is an engineering geological map?' 'How is an en¬

gineering map made?' and 'How is engineering geologicalinformation presented on such a map?'. Future efforts of theIAEG Commission on Engineering Geological Maps will be

devoted, among other things, to the techniques of engineeringgeological mapping and the amplification of the views set outin this guidebook. A very important part of future work willbe an attempt at international co-operation in the selectionand adoption of an agreed list of standard symbols for useon engineering geological maps.

The commission members realize that this guidebook isnot an exhaustive treatment of the subject, and hope thatmore complete versions may be prepared in the future. Anycomments and suggestions that would be of assistance inpreparing future guides to engineering geological mappingwould be greatly appreciated.

Members of the IAEG commission who have taken partin the preparation of this guide are :

Professor Milan Matula (Chairman), Department of En¬gineering Geology and Hydrogeology, Comenius Universi¬ty, Gottwaldo nam. 2, Bratislava (Czechoslovakia).

Professor W. R. Dearman (Editor), Department of Geology,Engineering Geology Unit, University of Newcastle-upon-Tyne (United Kingdom).

Professor G. A. Golodkovskaja, Geological Faculty, Mos-kovskij Universitet, Moskva 117234 (U.S.S.R.).

Professor Ing. M. Janjic, 1 100 Beograd, Tolstojeva 5 (Yugos¬lavia) .

Dr A. Pahl, Bundesanstalt für Geowissenschaften und Roh¬stoffe, 3 Hannover, Postfach 230153 (Federal Republic ofGermany).

A. Peter, Service Géologique Régional Massif Central,22 Avenue de Lempdes, 63800 Cournon d'Auvergne(France).

Mrs Dorothy H. Radbruch-Hall (Secretary), United StatesGeological Survey, 345 Middlefield Road, Menlo Park,CA 94025 (United States of America).

10

Principles 2

2.1 Introduction

The purpose of engineering geology is to provide basic infor¬mation for the planning of land-use and for the planning,design, construction and maintenance of civil engineeringworks. Such information is needed to assess the feasibility ofthe proposed land-use or engineering undertaking, and forthe latter to assist in the selection of the most appropriatetype and method of construction, to ensure the stability of a

structure in its natural setting, and to aid the performance ofnecessary maintenance. Engineering geological research andmapping are therefore mainly directed towards understand¬ing the interrelationships between the geological environ¬ment and the engineering situation; the nature and relation¬ships of the individual geological components; the activegeodynamic processes and the prognosis of processes likelyto result from the changes being made.

For each situation this implies a unique dynamic geo¬

logical system of interrelated and interdependent phenomenaand processes which can only be very incompletely under¬stood and represented. The principal factors creating the en¬

gineering geological conditions of an individual site or areaare the rocks and soils, water, geomorphological conditionsand geodynamic processes.

A map provides the best impression of a geological envi¬ronment, including the character and variety of engineeringgeological conditions, their individual components and theirinterrelationships. But it is a simplified model of the factsand the complexity of various dynamic geological factors cannever be entirely represented. The degree of simplificationdepends mainly on the purpose and scale of the map, therelative importance of specific engineering geological factorsor relationships, the accuracy of the information and on thetechniques of representation used.

An engineering geological map should fulfil the follow¬ing requirements :

1. It should portray the objective information necessary toevaluate the engineering geological features involved inregional planning, in the selection of both a site and themost suitable method of construction, and in mining.

2. It should make it possible to foresee the changes in thegeological situation likely to be brought about by a pro¬posed undertaking and to suggest any necessary preven¬tive measures.

3. It should present information in such a way that it is

easily understood by professional users who may not begeologists.

Engineering geological maps should be based on geological,hydrogeological and geomorphological maps, but must pre¬

sent and evaluate the basic facts provided by these maps interms of engineering geology.

2.2 Definition of an engineeringgeological map

An engineering geological map is a type of geological mapwhich provides a generalized representation of all those com¬ponents of a geological environment of significance in land-use planning, and in design, construction and maintenanceas applied to civil and mining engineering.

Geological features represented on engineering geologi¬cal maps are :

1. The character of the rocks and soils, including their distri¬bution, stratigraphical and structural arrangement, age,genesis, lithology, physical state, and their physical andmechanical properties.

2. Hydrogeological conditions, including the distribution ofwater-bearing soils and rocks, zones of saturated opendiscontinuities, depth to water table and its range of fluc¬tuation, regions of confined water and piezometric levels,storage coefficients, direction of flow; springs, rivers,lakes and the limits and occurrence interval of flooding;pH, salinity, corrosiveness.

3. Geomorphological conditions, including surface topogra¬phy and important elements of the landscape.

4. Geodynamic phenomena, including erosion and deposi¬tion, aeolian phenomena, permafrost, slope movements,formation of karstic conditions, suffusion, subsidence,volume changes in soil, data on seismic phenomena in¬

cluding active faults, current regional tectonic move¬

ments, and volcanic activity.Engineering geological maps should include interpretativecross-sections and an explanatory text and legend. They mayalso include documentation data which have been collectedfor the preparation of the map. More than one map sheet

may be required to show all this information.

11

Principles 2

2.1 Introduction

The purpose of engineering geology is to provide basic infor¬mation for the planning of land-use and for the planning,design, construction and maintenance of civil engineeringworks. Such information is needed to assess the feasibility ofthe proposed land-use or engineering undertaking, and forthe latter to assist in the selection of the most appropriatetype and method of construction, to ensure the stability of a

structure in its natural setting, and to aid the performance ofnecessary maintenance. Engineering geological research andmapping are therefore mainly directed towards understand¬ing the interrelationships between the geological environ¬ment and the engineering situation; the nature and relation¬ships of the individual geological components; the activegeodynamic processes and the prognosis of processes likelyto result from the changes being made.

For each situation this implies a unique dynamic geo¬

logical system of interrelated and interdependent phenomenaand processes which can only be very incompletely under¬stood and represented. The principal factors creating the en¬

gineering geological conditions of an individual site or areaare the rocks and soils, water, geomorphological conditionsand geodynamic processes.

A map provides the best impression of a geological envi¬ronment, including the character and variety of engineeringgeological conditions, their individual components and theirinterrelationships. But it is a simplified model of the factsand the complexity of various dynamic geological factors cannever be entirely represented. The degree of simplificationdepends mainly on the purpose and scale of the map, therelative importance of specific engineering geological factorsor relationships, the accuracy of the information and on thetechniques of representation used.

An engineering geological map should fulfil the follow¬ing requirements :

1. It should portray the objective information necessary toevaluate the engineering geological features involved inregional planning, in the selection of both a site and themost suitable method of construction, and in mining.

2. It should make it possible to foresee the changes in thegeological situation likely to be brought about by a pro¬posed undertaking and to suggest any necessary preven¬tive measures.

3. It should present information in such a way that it is

easily understood by professional users who may not begeologists.

Engineering geological maps should be based on geological,hydrogeological and geomorphological maps, but must pre¬

sent and evaluate the basic facts provided by these maps interms of engineering geology.

2.2 Definition of an engineeringgeological map

An engineering geological map is a type of geological mapwhich provides a generalized representation of all those com¬ponents of a geological environment of significance in land-use planning, and in design, construction and maintenanceas applied to civil and mining engineering.

Geological features represented on engineering geologi¬cal maps are :

1. The character of the rocks and soils, including their distri¬bution, stratigraphical and structural arrangement, age,genesis, lithology, physical state, and their physical andmechanical properties.

2. Hydrogeological conditions, including the distribution ofwater-bearing soils and rocks, zones of saturated opendiscontinuities, depth to water table and its range of fluc¬tuation, regions of confined water and piezometric levels,storage coefficients, direction of flow; springs, rivers,lakes and the limits and occurrence interval of flooding;pH, salinity, corrosiveness.

3. Geomorphological conditions, including surface topogra¬phy and important elements of the landscape.

4. Geodynamic phenomena, including erosion and deposi¬tion, aeolian phenomena, permafrost, slope movements,formation of karstic conditions, suffusion, subsidence,volume changes in soil, data on seismic phenomena in¬

cluding active faults, current regional tectonic move¬

ments, and volcanic activity.Engineering geological maps should include interpretativecross-sections and an explanatory text and legend. They mayalso include documentation data which have been collectedfor the preparation of the map. More than one map sheet

may be required to show all this information.

11


2.3 Classification of engineeringgeological maps

Engineering geological maps may be classified according topurpose, content and scale.

2.3.1 According to purpose, they may be :

2.3.1.1 Special purpose, providing information either onone specific aspect of engineering geology, or for one spe¬

cific purpose.2.3.1.2 Multipurpose, providing information covering

many aspects of engineering geology for a variety of plan¬ning and engineering purposes.

2.3.2 According to content, they may be :

2.3.2.1 Analytical maps, giving details of, or evaluating in¬

dividual components of the geological environment. Theircontent is, as a rule, expressed in the title, for example,map of weathering grades, jointing map, seismic hazardmap.

2.3.2.2 Comprehensive maps. These are of two kinds theymay be maps of engineering geological conditions depict¬ing all the principal components of the engineering geolog¬ical environment; on the other hand they may be maps ofengineering geological zoning, evaluating and classifyingindividual territorial units on the basis of the uniformity oftheir engineering geological conditions. These two typesmay be combined on small-scale maps.

2.3.2.3 Auxiliary maps. These present factual data and are,for example, documentation maps, structural contourmaps, isopachyte maps.

2.3.2.4 Complementary maps. These include geological,tectonic, geomorphological, pedological, geophysical andhydrogeological maps. They are maps of basic data whichare sometimes included with a set of engineering geologi¬cal maps.

2.3.3 According to scale, they may be :

2.3.3.1 Large-scale: 1 : 10000 and greater.2.3.3.2 Medium-scale: less than 1 : 10000 and greater than

1 : 100000.2.3.3.3 Small-scale : 1 : 100000 and less.

2.4 Principles of classification ofrocks and soils for engineeringgeological mapping

The boundaries of rock and soil units shown on engineeringgeological maps of various scales should delimit rock andsoil units which are characterized by a certain degree ofhomogeneity in basic engineering geological properties.

The main problem in engineering geological mapping is

the selection of those geological features of rocks and soilswhich are closely related to physical properties, such as

strength, deformability, durability, permeability, which areimportant in engineering geology. This is because, at present,we lack regional data on the variability of engineering prop¬erties of rocks and soils. Neither have suitable methods andtechniques been developed for determining them in sufficientquantity, over large areas, quantitatively, quickly and cheap¬

ly. It is for this reason that we have to use those geologicalproperties which best indicate physical or engineering geo

logical characteristics. These are: (a) mineralogical composi¬tion closely related to specific gravity, Atterberg limits andplasticity index; (b) textural and structural characteristics,such as particle size distribution, related to unit weight,porosity; (c) moisture content, saturation moisture content,consistency, degree of weathering and alteration, and joint¬ing, related to the physical state of soils and rocks and indi¬cating strength properties, deformation characteristics, per¬

meability and durability.Classification of rocks and soils on engineering geologi¬

cal maps should be based on the principle that the physicalor engineering geological properties of a rock in its presentstate are dependent on the combined effects of mode of ori¬gin, subsequent diagenetic, metamorphic and tectonic histo¬ry, and on weathering processes. This principle of classifica¬tion makes it possible not only to determine the reasons forthe lithological and physical characteristic of soils and rocks,but also for their spatial distribution. This is a basic principleof engineering geological mapping as of other geologicalmapping, and implies not only the classification of individualrock samples but also the use of many individual rock sam¬

ples, field observations and measurements to delineate uni¬form and continuous rock units.

The following classification,1 based on lithology andmode of origin, is suggested: (a) engineering geological type(ET); (b) lithological type (LT); (c) lithological complex(LC); (d) lithological suite (LS). There will be differentdegrees of homogeneity for each unit.

The engineering geological type has the highest degreeof physical homogeneity. It should be uniform in lithologicalcharacter and physical state. These units can be charac¬

terized by statistically determined values derived fromindividual determinations of physical and mechanicalproperties and are generally shown only on large-scale maps.

A lithological type is homogeneous throughout in com¬position, texture and structure, but usually is not uniform inphysical state. Reliable values of average mechanical proper¬ties cannot be given for the entire unit; usually only a gener¬

al idea of engineering properties, with a range of values, canbe presented. These units are used on large-scale, and wherepossible, on medium-scale maps.

A lithological complex comprises a set of geneticallyrelated lithological types developed under specific palaeogeo-graphical and geotectonic conditions. Within a lithologicalcomplex the spatial arrangement of lithological types is uni¬form and distinctive for that complex, but a lithologicalcomplex is not necessarily uniform in either lithologicalcharacter or physical state. In consequence, it is not possibleto define the physical and mechanical properties of the wholelithological complex, but only to give data on the individuallithological types comprising the complex and to indicate thegeneral behaviour of the whole lithological complex. Thelithological complex is used as a mapping unit on medium-scale and some small-scale maps.

1. The classification adopted for engineering geological rock and soil units may be

compared to the unit terms used in lithostratigraphical classification (Hedberg, 1972)

The conventional hierarchy of lithostratigraphical terms is as followsBed = named or unnamed distinctive individual layer;Member = named or unnamed lithological entity within a formation ;

Formation = fundamental unit of lithostratigraphy;Group = two or more formationsThe unit terms are used in engineering geology without any stratigraphical implica¬tions and in fact cannot be used in that way, and it is for this reason that theconventional lithostratigraphical terms were not used and a new set of terms wereadopted specially for engineering geological use There is, however, an approximategeneral equivalence of terms , for example engineering geological type = bed , lithologi¬cal type = member, lithological complex = formation, lithological suite = group

12


2.3 Classification of engineeringgeological maps

Engineering geological maps may be classified according topurpose, content and scale.

2.3.1 According to purpose, they may be :

2.3.1.1 Special purpose, providing information either onone specific aspect of engineering geology, or for one spe¬

cific purpose.2.3.1.2 Multipurpose, providing information covering

many aspects of engineering geology for a variety of plan¬ning and engineering purposes.

2.3.2 According to content, they may be :

2.3.2.1 Analytical maps, giving details of, or evaluating in¬

dividual components of the geological environment. Theircontent is, as a rule, expressed in the title, for example,map of weathering grades, jointing map, seismic hazardmap.

2.3.2.2 Comprehensive maps. These are of two kinds theymay be maps of engineering geological conditions depict¬ing all the principal components of the engineering geolog¬ical environment; on the other hand they may be maps ofengineering geological zoning, evaluating and classifyingindividual territorial units on the basis of the uniformity oftheir engineering geological conditions. These two typesmay be combined on small-scale maps.

2.3.2.3 Auxiliary maps. These present factual data and are,for example, documentation maps, structural contourmaps, isopachyte maps.

2.3.2.4 Complementary maps. These include geological,tectonic, geomorphological, pedological, geophysical andhydrogeological maps. They are maps of basic data whichare sometimes included with a set of engineering geologi¬cal maps.

2.3.3 According to scale, they may be :

2.3.3.1 Large-scale: 1 : 10000 and greater.2.3.3.2 Medium-scale: less than 1 : 10000 and greater than

1 : 100000.2.3.3.3 Small-scale : 1 : 100000 and less.

2.4 Principles of classification ofrocks and soils for engineeringgeological mapping

The boundaries of rock and soil units shown on engineeringgeological maps of various scales should delimit rock andsoil units which are characterized by a certain degree ofhomogeneity in basic engineering geological properties.

The main problem in engineering geological mapping is

the selection of those geological features of rocks and soilswhich are closely related to physical properties, such as

strength, deformability, durability, permeability, which areimportant in engineering geology. This is because, at present,we lack regional data on the variability of engineering prop¬erties of rocks and soils. Neither have suitable methods andtechniques been developed for determining them in sufficientquantity, over large areas, quantitatively, quickly and cheap¬

ly. It is for this reason that we have to use those geologicalproperties which best indicate physical or engineering geo

logical characteristics. These are: (a) mineralogical composi¬tion closely related to specific gravity, Atterberg limits andplasticity index; (b) textural and structural characteristics,such as particle size distribution, related to unit weight,porosity; (c) moisture content, saturation moisture content,consistency, degree of weathering and alteration, and joint¬ing, related to the physical state of soils and rocks and indi¬cating strength properties, deformation characteristics, per¬

meability and durability.Classification of rocks and soils on engineering geologi¬

cal maps should be based on the principle that the physicalor engineering geological properties of a rock in its presentstate are dependent on the combined effects of mode of ori¬gin, subsequent diagenetic, metamorphic and tectonic histo¬ry, and on weathering processes. This principle of classifica¬tion makes it possible not only to determine the reasons forthe lithological and physical characteristic of soils and rocks,but also for their spatial distribution. This is a basic principleof engineering geological mapping as of other geologicalmapping, and implies not only the classification of individualrock samples but also the use of many individual rock sam¬

ples, field observations and measurements to delineate uni¬form and continuous rock units.

The following classification,1 based on lithology andmode of origin, is suggested: (a) engineering geological type(ET); (b) lithological type (LT); (c) lithological complex(LC); (d) lithological suite (LS). There will be differentdegrees of homogeneity for each unit.

The engineering geological type has the highest degreeof physical homogeneity. It should be uniform in lithologicalcharacter and physical state. These units can be charac¬

terized by statistically determined values derived fromindividual determinations of physical and mechanicalproperties and are generally shown only on large-scale maps.

A lithological type is homogeneous throughout in com¬position, texture and structure, but usually is not uniform inphysical state. Reliable values of average mechanical proper¬ties cannot be given for the entire unit; usually only a gener¬

al idea of engineering properties, with a range of values, canbe presented. These units are used on large-scale, and wherepossible, on medium-scale maps.

A lithological complex comprises a set of geneticallyrelated lithological types developed under specific palaeogeo-graphical and geotectonic conditions. Within a lithologicalcomplex the spatial arrangement of lithological types is uni¬form and distinctive for that complex, but a lithologicalcomplex is not necessarily uniform in either lithologicalcharacter or physical state. In consequence, it is not possibleto define the physical and mechanical properties of the wholelithological complex, but only to give data on the individuallithological types comprising the complex and to indicate thegeneral behaviour of the whole lithological complex. Thelithological complex is used as a mapping unit on medium-scale and some small-scale maps.

1. The classification adopted for engineering geological rock and soil units may be

compared to the unit terms used in lithostratigraphical classification (Hedberg, 1972)

The conventional hierarchy of lithostratigraphical terms is as followsBed = named or unnamed distinctive individual layer;Member = named or unnamed lithological entity within a formation ;

Formation = fundamental unit of lithostratigraphy;Group = two or more formationsThe unit terms are used in engineering geology without any stratigraphical implica¬tions and in fact cannot be used in that way, and it is for this reason that theconventional lithostratigraphical terms were not used and a new set of terms wereadopted specially for engineering geological use There is, however, an approximategeneral equivalence of terms , for example engineering geological type = bed , lithologi¬cal type = member, lithological complex = formation, lithological suite = group

12

Principles

The lithological suite comprises many lithological com¬plexes that developed under generally similar palaeogeo-graphical and tectonic conditions. It has certain commonlithological characteristics throughout which impart a gener¬al unity to the suite and serve to distinguish it from othersuites. Only very general engineering geological properties ofa lithological suite can be defined. These units are only usedon small-scale maps.

On engineering geological maps the distribution ofmapping units as well as their stratigraphical and structuralarrangements and age relationships are shown. The engineer¬ing geological properties of the map units should be de¬

scribed in an accompanying explanatory legend. These mapunits will be used on both multipurpose and special purposecomprehensive or analytical maps.

2.5 Hydrogeological conditions

Hydrogeological conditions affect land-use, planning, siteselection and the cost, durability and even the safety of struc¬tures. Ground and surface waters play a prominent part insuch geodynamic processes as weathering, slope movements,mechanical and chemical suffusion, the development of kar-stic conditions, volume changes by shrinking and swelling,and collapse in loessic soils. Rock and soil properties areoften changed by groundwater. Groundwater may influenceexcavation and construction methods by flowing into exca¬

vations, by producing seepage forces and uplift pressures andby its corrosive action. Hydrogeological conditions may alsoaffect underground waste disposal.

Natural groundwater and surface water régimes may bedirectly influenced by hydraulic structures and by extractionof groundwater, and indirectly by factors such as urbaniza¬tion and deforestation which increase runoff, sediment loadin streams and erosion, thereby influencing other processessuch as slope movement and sedimentation.

One aim of engineering geology, facilitated by the provi¬sion of hydrogeological data on maps, is the prediction ofundesirable changes in the hydrogeological régime and therecommendation of procedures to avoid them. In engineer¬ing geological mapping, therefore, the following importantinformation on hydrogeological conditions should be eva¬

luated and represented on maps: the distribution of surfaceand subsurface water; infiltration conditions; water content;direction and velocity of groundwater flow ; springs and seep¬

ages from individual water-bearing horizons; depth to wa¬

ter table and its range of fluctuation; regions of confinedwater and piezometric levels; hydrochemical properties suchas pH, salinity, corrosiveness; and presence of bacterial orother pollutants.

On small-scale maps hydrogeological information isrepresented by symbols and numbers. On medium-scalemaps the water table may be represented by contours and itsrange of fluctuation indicated by numbers. In mountainousregions this is not possible and depth to water table andother features can only be shown by numbers. Both depthsto confined water and piezometric levels can be shown bycontours. On large-scale maps hydrogeological conditionsare represented by isohypses, isobaths and isopiestic lines,with known fluctuations shown numerically.

2.6 Geomorphological conditions

Geomorphological mapping is helpful in explaining the recenthistory ofdevelopment of the landscape such as the formationof valleys, terraces, slope configuration and the processesactive in the landscape at the present time. It is an essentialpart of engineering geological mapping which can be carriedout quickly and cheaply and is often a decisive factor inplanning an engineering geological investigation.

Evaluation of geomorphological conditions in engineer¬ing geological mapping should be more than a simple de¬

scription of surface topography. It should include an expla¬nation of the relationship between surface conditions and thegeological setting; the origin, development and age of indi¬vidual geomorphological elements; the influence of geo¬

morphological conditions on hydrology and geodynamicprocesses. Also very important in engineering geology is theprediction of impending development of geomorphologicalfeatures such as the lateral erosion of river banks, movementof dunes, collapse in karst or undermined areas.

Surface topography is shown by contours on maps of allscales. Point symbols are used to indicate significant geomor¬phological elements on small-scale maps. On medium andlarge-scale maps the actual boundaries and details of geo¬

morphological features can be mapped.

2.7 Evaluation of geodynamicphenomena

Geodynamic phenomena are those geological features of theenvironment resulting from geological processes active at thepresent time. Excluded are depositional or alterationprocesses as these are included in the description of rock andsoils units. The geological features include those due to ero¬

sion and deposition, aeolian processes, slope movements,permafrost, formation of karstic conditions, suffusion,volume changes in soil, seismic and volcanic activity. Allthese features are important in engineering geological plan¬ning and construction. They can be shown on special-pur¬pose or multipurpose maps, and on analytical or comprehen¬sive maps. The amount of detail shown depends on the scale

of the map. It is important to show not only the features butalso the conditions favouring their development, their inten¬sity and frequency of occurrence.

Excessive erosion commonly produces many steep-sidedgullies and ravines on hillsides and in extreme cases

badlands. Erosion removes material and steepens slopesalong streams, reservoirs and natural shorelines. Erosion ofhillsides not only damages agricultural land but also causes

construction problems. It creates an irregular surface, in¬

creases sediment load in streams and thereby increases ero¬

sion, removes lateral support from parts of slopes thus in¬

creasing the possibility of slope movements. Sedimentwashed from hillsides may accumulate in culverts, stormdrains, gutters and other drainage facilities, or contribute tothe rapid silting up of reservoirs.

Favourable conditions for excessive erosion are softrocks of low permeability, moderate to steep slopes, sparsevegetation and high rainfall concentrated in a short period oftime. Contributory factors are overgrazing, overcultivation,deforestation and urban development.

13

Principles

The lithological suite comprises many lithological com¬plexes that developed under generally similar palaeogeo-graphical and tectonic conditions. It has certain commonlithological characteristics throughout which impart a gener¬al unity to the suite and serve to distinguish it from othersuites. Only very general engineering geological properties ofa lithological suite can be defined. These units are only usedon small-scale maps.

On engineering geological maps the distribution ofmapping units as well as their stratigraphical and structuralarrangements and age relationships are shown. The engineer¬ing geological properties of the map units should be de¬

scribed in an accompanying explanatory legend. These mapunits will be used on both multipurpose and special purposecomprehensive or analytical maps.

2.5 Hydrogeological conditions

Hydrogeological conditions affect land-use, planning, siteselection and the cost, durability and even the safety of struc¬tures. Ground and surface waters play a prominent part insuch geodynamic processes as weathering, slope movements,mechanical and chemical suffusion, the development of kar-stic conditions, volume changes by shrinking and swelling,and collapse in loessic soils. Rock and soil properties areoften changed by groundwater. Groundwater may influenceexcavation and construction methods by flowing into exca¬

vations, by producing seepage forces and uplift pressures andby its corrosive action. Hydrogeological conditions may alsoaffect underground waste disposal.

Natural groundwater and surface water régimes may bedirectly influenced by hydraulic structures and by extractionof groundwater, and indirectly by factors such as urbaniza¬tion and deforestation which increase runoff, sediment loadin streams and erosion, thereby influencing other processessuch as slope movement and sedimentation.

One aim of engineering geology, facilitated by the provi¬sion of hydrogeological data on maps, is the prediction ofundesirable changes in the hydrogeological régime and therecommendation of procedures to avoid them. In engineer¬ing geological mapping, therefore, the following importantinformation on hydrogeological conditions should be eva¬

luated and represented on maps: the distribution of surfaceand subsurface water; infiltration conditions; water content;direction and velocity of groundwater flow ; springs and seep¬

ages from individual water-bearing horizons; depth to wa¬

ter table and its range of fluctuation; regions of confinedwater and piezometric levels; hydrochemical properties suchas pH, salinity, corrosiveness; and presence of bacterial orother pollutants.

On small-scale maps hydrogeological information isrepresented by symbols and numbers. On medium-scalemaps the water table may be represented by contours and itsrange of fluctuation indicated by numbers. In mountainousregions this is not possible and depth to water table andother features can only be shown by numbers. Both depthsto confined water and piezometric levels can be shown bycontours. On large-scale maps hydrogeological conditionsare represented by isohypses, isobaths and isopiestic lines,with known fluctuations shown numerically.

2.6 Geomorphological conditions

Geomorphological mapping is helpful in explaining the recenthistory ofdevelopment of the landscape such as the formationof valleys, terraces, slope configuration and the processesactive in the landscape at the present time. It is an essentialpart of engineering geological mapping which can be carriedout quickly and cheaply and is often a decisive factor inplanning an engineering geological investigation.

Evaluation of geomorphological conditions in engineer¬ing geological mapping should be more than a simple de¬

scription of surface topography. It should include an expla¬nation of the relationship between surface conditions and thegeological setting; the origin, development and age of indi¬vidual geomorphological elements; the influence of geo¬

morphological conditions on hydrology and geodynamicprocesses. Also very important in engineering geology is theprediction of impending development of geomorphologicalfeatures such as the lateral erosion of river banks, movementof dunes, collapse in karst or undermined areas.

Surface topography is shown by contours on maps of allscales. Point symbols are used to indicate significant geomor¬phological elements on small-scale maps. On medium andlarge-scale maps the actual boundaries and details of geo¬

morphological features can be mapped.

2.7 Evaluation of geodynamicphenomena

Geodynamic phenomena are those geological features of theenvironment resulting from geological processes active at thepresent time. Excluded are depositional or alterationprocesses as these are included in the description of rock andsoils units. The geological features include those due to ero¬

sion and deposition, aeolian processes, slope movements,permafrost, formation of karstic conditions, suffusion,volume changes in soil, seismic and volcanic activity. Allthese features are important in engineering geological plan¬ning and construction. They can be shown on special-pur¬pose or multipurpose maps, and on analytical or comprehen¬sive maps. The amount of detail shown depends on the scale

of the map. It is important to show not only the features butalso the conditions favouring their development, their inten¬sity and frequency of occurrence.

Excessive erosion commonly produces many steep-sidedgullies and ravines on hillsides and in extreme cases

badlands. Erosion removes material and steepens slopesalong streams, reservoirs and natural shorelines. Erosion ofhillsides not only damages agricultural land but also causes

construction problems. It creates an irregular surface, in¬

creases sediment load in streams and thereby increases ero¬

sion, removes lateral support from parts of slopes thus in¬

creasing the possibility of slope movements. Sedimentwashed from hillsides may accumulate in culverts, stormdrains, gutters and other drainage facilities, or contribute tothe rapid silting up of reservoirs.

Favourable conditions for excessive erosion are softrocks of low permeability, moderate to steep slopes, sparsevegetation and high rainfall concentrated in a short period oftime. Contributory factors are overgrazing, overcultivation,deforestation and urban development.

13


The erosion features commonly shown on engineeringgeological maps are hillside gullies and ravines, and riverbanks and shorelines that are being actively eroded.

Aeolian processes are generally among the less damag¬ing geodynamic processes, but may be troublesome to en¬

gineering structures in certain areas. Dunes that develop insandy arid and semi-arid regions can move across and blocktransportation lines which then require constant mainte¬nance. Overgrazing, overcultivation or deforestation cancreate dune fields in some sandy areas. Conversely, dunescan often be stabilized by planting. Dunes and similar fea¬

tures should be shown on engineering geological maps.Slope movements take place under the influence of grav¬

ity and include creep, slide, flow and fall of all types of rockand soil.

Geological conditions favourable for the developmentof slope movements are varied. They include hard resistantrocks overlying softer ones, such as volcanic rock over clay,or sandstone beds with shale overlying shales with minorintercalations of sandstone, or relatively undisturbed bedsover rocks highly sheared by faulting; rocks that are highlyjointed, fractured or sheared; hard and soft rocks alternatingin a slope; unconsolidated sediments overlying relatively im¬

permeable bedrock; presence of groundwater. Slope move¬ments are caused or triggered off by other natural processesor by the activities of man. The conditions suitable for slopemovements, and the features that are the result of suchmovements can be shown on maps; the factors that triggerthe movement often cannot be shown.

The factors that cause slope movement can be dividedinto those that reduce shear strength and those that increaseshear stresses on the slope.

Permafrost, permanently frozen ground, is widespreadin arctic and subarctic regions. Construction problems canbe expected in permanently frozen fine-gained materials suchas silt, particularly those containing ice lenses and wedges.Certain features indicating permafrost can be shown onmaps; for example, polygonal ground, thaw lakes and subsi¬

dence due to thawing after interference by man.In northern regions, seasonal freezing and thawing of

the ground, particularly in fine-grained materials, can alsocause problems such as frost heaving of piles or damage tohighways.

Karst features result from the solution of rocks. Com¬mon karst features on the surface are sinkholes, blind valleysand dry valleys with steep walls; underground, cave systemsare also common. In addition the bedrock surface is ex¬

tremely irregular and is usually covered by soils of varyingcompressibility.

Suffusion is the washing out of fine particles from un¬

consolidated materials, in particular sands and gravels. It is aminor geodynamic process, but may give rise to considerableproblems in the design of hydraulic structures. The mostcommon suffusion feature that can be shown on a map is thelocation of upwelling water or suffusion springs.

Volume changes in shrinking and swelling soils cancause damage to structures. Areas of such soils should beshown on engineering geological maps.

Geodynamic seismic features are the result of seismicactivity recent enough for the effects still to be visible as

geomorphological forms. In addition, it is sometimes pos¬

sible to show on engineering geological maps areas of conti¬nuing relative tectonic uplift and depression as determinedby geodetic measurements, and inferred active faults deter¬mined from historical records or geological data such as the

juxtaposition of recent and older deposits, or raised andtilted terraces and shorelines. Features associated with activefaults include offset streams, terraces and man-made struc¬

tures; scarps; sag ponds; shutterridges ; lines of springs;linear trenches.

Volcanic activity may have associated seismic activityand current local uplift and depression, but it is the frequen¬cy and intensity of the activity and the nature, location andextent of the volcanic products that may be of more impor¬tance in engineering geology.

It should be the aim of engineering geology not only toshow the extent and distribution of geodynamic features, butalso wherever possible to indicate their age and degree ofactivity.

On small-scale maps point data on geodynamic featurescan be shown by symbols. On medium-scale maps areas ofthe occurrence of geodynamic features should be delineatedand the boundaries of individual features should be shownwhere possible. The actual boundaries of individual geo¬

dynamic features, and where possible their internal structures,can be shown on large-scale maps.

2.8 Principles of engineeringgeological zoning

Comprehensive engineering geological maps may present in¬

formation in terms of engineering geological zoning. Theseare individual areas on the map which are approximatelyhomogeneous in terms of engineering geological conditionsand the area covered by any particular map sheet may besubdivided into a number of distinctive zoning units.

The detail and degree of homogeneity of each engineer¬ing geological zoning unit will depend on the scale and pur¬pose of the map. For example, on small-scale maps the cri¬terion of zoning would be the general uniformity in the mainelements comprising the geological environment, such as

geotectonic structure or regional geomorphological features.On larger scale maps, zones are based on an evaluation ofthe uniformity of the structural arrangement and composi¬tion of rock and soil units, on hydrogeological conditions,and on geodynamic phenomena.

Engineering geological zoning can be undertaken eitherfor a general purpose or for a special purpose. On a map ofgeneral purpose zoning the following taxonomic natural ter¬

ritorial units would be recognized :

1. Regions, based on the uniformity of individual geotecton¬ic structural elements.

2. Areas, on the basis of the uniformity of individualregional geomorphological units.

3. Zones, on the basis of the lithological homogeneity andthe structural arrangement of lithofacial complexes ofrocks and soils.

4. Districts, in which hydrogeological conditions and geo¬

dynamic phenomena are uniform.In this way, the characteristics of a territory can be definedby zoning which, in turn, can then be used to evaluate thecomplexity of engineering geological conditions in individualterritorial units for land-use and engineering purposes.

A map of special purpose engineering geological zoningwould be prepared with a particular type of engineering un¬

dertaking in mind, for example, highways, dams, tunnels. Onsuch a map the zoning units would be based on the analysisof geological phenomena and on geotechnical parameters,and evaluated in terms of a particular engineering purpose.

14


The erosion features commonly shown on engineeringgeological maps are hillside gullies and ravines, and riverbanks and shorelines that are being actively eroded.

Aeolian processes are generally among the less damag¬ing geodynamic processes, but may be troublesome to en¬

gineering structures in certain areas. Dunes that develop insandy arid and semi-arid regions can move across and blocktransportation lines which then require constant mainte¬nance. Overgrazing, overcultivation or deforestation cancreate dune fields in some sandy areas. Conversely, dunescan often be stabilized by planting. Dunes and similar fea¬

tures should be shown on engineering geological maps.Slope movements take place under the influence of grav¬

ity and include creep, slide, flow and fall of all types of rockand soil.

Geological conditions favourable for the developmentof slope movements are varied. They include hard resistantrocks overlying softer ones, such as volcanic rock over clay,or sandstone beds with shale overlying shales with minorintercalations of sandstone, or relatively undisturbed bedsover rocks highly sheared by faulting; rocks that are highlyjointed, fractured or sheared; hard and soft rocks alternatingin a slope; unconsolidated sediments overlying relatively im¬

permeable bedrock; presence of groundwater. Slope move¬ments are caused or triggered off by other natural processesor by the activities of man. The conditions suitable for slopemovements, and the features that are the result of suchmovements can be shown on maps; the factors that triggerthe movement often cannot be shown.

The factors that cause slope movement can be dividedinto those that reduce shear strength and those that increaseshear stresses on the slope.

Permafrost, permanently frozen ground, is widespreadin arctic and subarctic regions. Construction problems canbe expected in permanently frozen fine-gained materials suchas silt, particularly those containing ice lenses and wedges.Certain features indicating permafrost can be shown onmaps; for example, polygonal ground, thaw lakes and subsi¬

dence due to thawing after interference by man.In northern regions, seasonal freezing and thawing of

the ground, particularly in fine-grained materials, can alsocause problems such as frost heaving of piles or damage tohighways.

Karst features result from the solution of rocks. Com¬mon karst features on the surface are sinkholes, blind valleysand dry valleys with steep walls; underground, cave systemsare also common. In addition the bedrock surface is ex¬

tremely irregular and is usually covered by soils of varyingcompressibility.

Suffusion is the washing out of fine particles from un¬

consolidated materials, in particular sands and gravels. It is aminor geodynamic process, but may give rise to considerableproblems in the design of hydraulic structures. The mostcommon suffusion feature that can be shown on a map is thelocation of upwelling water or suffusion springs.

Volume changes in shrinking and swelling soils cancause damage to structures. Areas of such soils should beshown on engineering geological maps.

Geodynamic seismic features are the result of seismicactivity recent enough for the effects still to be visible as

geomorphological forms. In addition, it is sometimes pos¬

sible to show on engineering geological maps areas of conti¬nuing relative tectonic uplift and depression as determinedby geodetic measurements, and inferred active faults deter¬mined from historical records or geological data such as the

juxtaposition of recent and older deposits, or raised andtilted terraces and shorelines. Features associated with activefaults include offset streams, terraces and man-made struc¬

tures; scarps; sag ponds; shutterridges ; lines of springs;linear trenches.

Volcanic activity may have associated seismic activityand current local uplift and depression, but it is the frequen¬cy and intensity of the activity and the nature, location andextent of the volcanic products that may be of more impor¬tance in engineering geology.

It should be the aim of engineering geology not only toshow the extent and distribution of geodynamic features, butalso wherever possible to indicate their age and degree ofactivity.

On small-scale maps point data on geodynamic featurescan be shown by symbols. On medium-scale maps areas ofthe occurrence of geodynamic features should be delineatedand the boundaries of individual features should be shownwhere possible. The actual boundaries of individual geo¬

dynamic features, and where possible their internal structures,can be shown on large-scale maps.

2.8 Principles of engineeringgeological zoning

Comprehensive engineering geological maps may present in¬

formation in terms of engineering geological zoning. Theseare individual areas on the map which are approximatelyhomogeneous in terms of engineering geological conditionsand the area covered by any particular map sheet may besubdivided into a number of distinctive zoning units.

The detail and degree of homogeneity of each engineer¬ing geological zoning unit will depend on the scale and pur¬pose of the map. For example, on small-scale maps the cri¬terion of zoning would be the general uniformity in the mainelements comprising the geological environment, such as

geotectonic structure or regional geomorphological features.On larger scale maps, zones are based on an evaluation ofthe uniformity of the structural arrangement and composi¬tion of rock and soil units, on hydrogeological conditions,and on geodynamic phenomena.

Engineering geological zoning can be undertaken eitherfor a general purpose or for a special purpose. On a map ofgeneral purpose zoning the following taxonomic natural ter¬

ritorial units would be recognized :

1. Regions, based on the uniformity of individual geotecton¬ic structural elements.

2. Areas, on the basis of the uniformity of individualregional geomorphological units.

3. Zones, on the basis of the lithological homogeneity andthe structural arrangement of lithofacial complexes ofrocks and soils.

4. Districts, in which hydrogeological conditions and geo¬

dynamic phenomena are uniform.In this way, the characteristics of a territory can be definedby zoning which, in turn, can then be used to evaluate thecomplexity of engineering geological conditions in individualterritorial units for land-use and engineering purposes.

A map of special purpose engineering geological zoningwould be prepared with a particular type of engineering un¬

dertaking in mind, for example, highways, dams, tunnels. Onsuch a map the zoning units would be based on the analysisof geological phenomena and on geotechnical parameters,and evaluated in terms of a particular engineering purpose.

14

Principles

2.9 General principles

The main principles of engineering geological mappingshould be applicable to maps of all types and all scales. Ifthis is done, it will be possible to compare maps prepared atthe same scale and at a variety of scales. The basic differencebetween maps at different scales should only be in theamount of data presented, and in the way in which informa¬tion is presented. For example, the scale of the map willdetermine whether a landslide is represented by a point sym¬

bol appropriate to small-scale maps. A generalized symbolrepresenting the type of landslide and occupying the actualarea covered by the landslide would be used on medium-

scale maps, whereas at large scales all the details within thelandslide area would have been mapped to scale.

On engineering geological maps, of all types and at allscales, the information provided should be presented in sucha way that not only the true nature but also the engineeringsignificance of the data can be understood and fully appre¬ciated.

2.10 Reference

Hedberg, H. D. (ed.). 1972. An international guide to stratigraph¬ie classification, terminology, and usage. Lethaia, vol. 5, p. 297-323. (International Subcommission on Stratigraphie Classifica¬tion, report no. 7B.)

15

Principles

2.9 General principles

The main principles of engineering geological mappingshould be applicable to maps of all types and all scales. Ifthis is done, it will be possible to compare maps prepared atthe same scale and at a variety of scales. The basic differencebetween maps at different scales should only be in theamount of data presented, and in the way in which informa¬tion is presented. For example, the scale of the map willdetermine whether a landslide is represented by a point sym¬

bol appropriate to small-scale maps. A generalized symbolrepresenting the type of landslide and occupying the actualarea covered by the landslide would be used on medium-

scale maps, whereas at large scales all the details within thelandslide area would have been mapped to scale.

On engineering geological maps, of all types and at allscales, the information provided should be presented in sucha way that not only the true nature but also the engineeringsignificance of the data can be understood and fully appre¬ciated.

2.10 Reference

Hedberg, H. D. (ed.). 1972. An international guide to stratigraph¬ie classification, terminology, and usage. Lethaia, vol. 5, p. 297-323. (International Subcommission on Stratigraphie Classifica¬tion, report no. 7B.)

15

Techniques for acquiringand interpreting data

3

3.1 IntroductionEngineering geological mapping has much in common withgeological mapping as the purpose of both types of mappingis to present information about the geological environment.From the point of view of the civil engineer one of the short¬comings of conventional geological maps is that rocks ofmarkedly different engineering properties may be groupedtogether as a single unit because they are of the same age andorigin. However, the scope of engineering geological map¬ping is wider as in addition to lithostratigraphical and struc¬tural information other components have to be considered.These mainly include the description and qualification ofsignificant physical and engineering properties of rocks andsoils, of the thickness and areal extent of geological forma¬tions, of groundwater conditions and of geodynamicphenomena.

A geological map provides the fundamental basis forengineering geological mapping. However, to meet the addi¬tional requirements of engineering geological maps specificmethods and techniques are employed for gathering and in¬terpreting engineering geological information. A difficultywhich is inherent in both geological and engineering geologi¬cal mapping techniques is that changes in the character ofrocks and soils are often gradational and can occur bothhorizontally and vertically.

3.2 General methods of geologicalmapping

Geological maps are usually prepared by adding geologicaldata to existing topographical maps, to topographical mapsmade specially for the purpose or to vertical aerial photo¬graphs. The accumulated geological information is inter¬preted and a synthesis of geological conditions, involvingdrawing structural and stratigraphical boundaries betweendefined units, may be prepared either at the same or a smal¬ler scale.

3.2.1 PREPARATION OF THETOPOGRAPHICAL BASE MAP

Where a topographical base map does not exist or is on toosmall a scale to be used for field-work, a map will have to bemade specially as a base for the geological map. A topo¬graphical map may be produced before the geological survey

starts either by conventional methods of ground survey orfrom vertical aerial photographs. Alternatively the geologistmay produce his own topographical map as the geologicalobservations are made. There are several methods of doingthis depending on the accuracy required, and methods in¬

cluding the pace-and-compass method, the hand-levelmethod, the altimeter method and the plane table methodare fully described in various textbooks. Terrestrial photo-grammetry may be useful in surveying steep rock slopes andfoundation conditions. Use of this photographic technique isdescribed in the literature.

3.2.2 ACQUISITION OF

GEOLOGICAL INFORMATION

The work entailed in assembling geological information forthe preparation of an engineering geological map follows aset pattern comprising a number of stages. A preliminarystep is the search for existing geological information on thearea to be mapped, supplemented by the study of maps andany existing aerial photographs. This is followed by re¬

connaissance of the area in which the available evidenceis assessed and new geological, geomorphological and geo¬

dynamic information is gathered; samples may be collectedfor initial laboratory study, and the general survey work maybe supplemented by geophysical tests and some un¬

sophisticated subsurface sampling using, for example, portabledrills and augers. The final stage, which may either be generalor devoted to the elucidation of conditions associated with aparticular construction site, will involve detailed field map¬ping (3.3), a variety of field investigations (3.4.1-3) and labo¬ratory and in situ tests (3.4.4).

3.3 Special requirements forengineering geological mapping

3.3.1 ENGINEERING GEOLOGICAL DESCRIPTION OF

ROCKS AND SOILS

The classifications of rocks and soils used by geologists arenot satisfactory for engineering purposes because significantproperties are not included in, and cannot always be inferredfrom, the usual geological description. It is, therefore,recommended for engineering geological mapping practice touse simple rock names supplemented by selected descriptive

17

Techniques for acquiringand interpreting data

3

3.1 IntroductionEngineering geological mapping has much in common withgeological mapping as the purpose of both types of mappingis to present information about the geological environment.From the point of view of the civil engineer one of the short¬comings of conventional geological maps is that rocks ofmarkedly different engineering properties may be groupedtogether as a single unit because they are of the same age andorigin. However, the scope of engineering geological map¬ping is wider as in addition to lithostratigraphical and struc¬tural information other components have to be considered.These mainly include the description and qualification ofsignificant physical and engineering properties of rocks andsoils, of the thickness and areal extent of geological forma¬tions, of groundwater conditions and of geodynamicphenomena.

A geological map provides the fundamental basis forengineering geological mapping. However, to meet the addi¬tional requirements of engineering geological maps specificmethods and techniques are employed for gathering and in¬terpreting engineering geological information. A difficultywhich is inherent in both geological and engineering geologi¬cal mapping techniques is that changes in the character ofrocks and soils are often gradational and can occur bothhorizontally and vertically.

3.2 General methods of geologicalmapping

Geological maps are usually prepared by adding geologicaldata to existing topographical maps, to topographical mapsmade specially for the purpose or to vertical aerial photo¬graphs. The accumulated geological information is inter¬preted and a synthesis of geological conditions, involvingdrawing structural and stratigraphical boundaries betweendefined units, may be prepared either at the same or a smal¬ler scale.

3.2.1 PREPARATION OF THETOPOGRAPHICAL BASE MAP

Where a topographical base map does not exist or is on toosmall a scale to be used for field-work, a map will have to bemade specially as a base for the geological map. A topo¬graphical map may be produced before the geological survey

starts either by conventional methods of ground survey orfrom vertical aerial photographs. Alternatively the geologistmay produce his own topographical map as the geologicalobservations are made. There are several methods of doingthis depending on the accuracy required, and methods in¬

cluding the pace-and-compass method, the hand-levelmethod, the altimeter method and the plane table methodare fully described in various textbooks. Terrestrial photo-grammetry may be useful in surveying steep rock slopes andfoundation conditions. Use of this photographic technique isdescribed in the literature.

3.2.2 ACQUISITION OF

GEOLOGICAL INFORMATION

The work entailed in assembling geological information forthe preparation of an engineering geological map follows aset pattern comprising a number of stages. A preliminarystep is the search for existing geological information on thearea to be mapped, supplemented by the study of maps andany existing aerial photographs. This is followed by re¬

connaissance of the area in which the available evidenceis assessed and new geological, geomorphological and geo¬

dynamic information is gathered; samples may be collectedfor initial laboratory study, and the general survey work maybe supplemented by geophysical tests and some un¬

sophisticated subsurface sampling using, for example, portabledrills and augers. The final stage, which may either be generalor devoted to the elucidation of conditions associated with aparticular construction site, will involve detailed field map¬ping (3.3), a variety of field investigations (3.4.1-3) and labo¬ratory and in situ tests (3.4.4).

3.3 Special requirements forengineering geological mapping

3.3.1 ENGINEERING GEOLOGICAL DESCRIPTION OF

ROCKS AND SOILS

The classifications of rocks and soils used by geologists arenot satisfactory for engineering purposes because significantproperties are not included in, and cannot always be inferredfrom, the usual geological description. It is, therefore,recommended for engineering geological mapping practice touse simple rock names supplemented by selected descriptive

17


terms. These terms should be applied to both the rockmaterial and the rock mass and should include a descriptionof colour, grain size, texture, structure, discontinuities withinthe mass, weathered state, alteration state, strength proper¬ties, permeability and other terms indicating special en¬

gineering characteristics.Adequate description of a rock or soil mass may require

additional information including the dip and strike, or theattitude, of structures and discontinuities, the surface charac¬ter of bedding planes and other discontinuities, the variabili¬ty of structures and discontinuities, the details of the wea¬

thering profile. Of particular importance is the estimation ofthe degree of isotropy and homogeneity of the rock mass.

All these characteristics should be described by usingsemi-quantitative descriptive terms which have been definedfor use in different countries.

3.3.2 MAPPING OF ROCKS AND SOILS FOR

ENGINEERING PURPOSES

From the results of an engineering geological survey, theengineering geologist should aim to produce a map on whichunits are defined by engineering properties. In general theboundaries of these units could be expected to follow litho¬logical boundaries, but the engineering property boundariesmight well bear no relation to either geological structure orto stratigraphical boundaries. An example would be wheredeep weathering has differentially affected various rocktypes. The boundaries of rock and soil units shown on en¬

gineering geological maps of various scales should therefore,as has been stated before (2.4), delimit rock and soil unitswhich are characterized by a certain degree of homogeneityin basic physical properties. Selection of an appropriatemethod for drawing boundaries to mapping units in the fielddepends in the first instance on the purpose for which themapping is being undertaken. In turn, purpose will dictatean appropriate scale and scale will define the basic taxonom-ic or mapping unit which may be the lithological suite, thelithological complex, the lithological type or the engineeringgeological type.

There are suitable methods for mapping the boundariesof each of these units, and these are:1 . Lithological suite. The interpretation of existing geologi¬

cal maps; reconnaissance mapping; photogeology.2. Lithological complex. Areal mapping with facial analysis

to group together genetically related lithological types.3. Lithological type. Detailed areal mapping and pétro¬

graphie investigation.4. Engineering geological type. Detailed investigation of the

physical state of the rock or soil mass within a mappedlithological type.

Methods used in characterizing each of the basic taxonomicor mapping units include :

1. Lithological suite. Evaluation of probable rock behaviourfrom a knowledge of the properties of known rock types.

2. Lithological complex. Geophysical investigations in thefield. Systematic boring and sampling in the field. In situtesting. Laboratory or field-laboratory testing of physicaland index properties. Pétrographie investigation and theevaluation of rock behaviour from a knowledge of theproperties of known rock types.

3. Lithological type. Detailed pétrographie investigation.Geophysical testing in the field. Systematic determinationof index properties in the laboratory. In situ and laborato¬ry testing of mechanical and other rock properties.

4. Engineering geological type. In situ testing of mechanicaland other rock properties. Systematic laboratory testingof physical and mechanical properties.

Basic requirements for both investigation methods andcharacterization methods in delineating mapping units aresummarized in Figure 1 in which the application of themethods to maps at successively larger scales is illustrated.

3.3.3 MAPPING HYDROGEOLOGICAL CONDITIONS

The principal hydrogeological conditions which need to berecorded or monitored in engineering geological mapping areof two types. The first is concerned with surface information,such as springs, seepages, rivers, lakes.

The second relates to subsurface information obtainedfrom existing boreholes and wells or from exploratory bore¬holes made for the purpose. Hydrogeological conditionsshould be quantified wherever possible.

Springs and seepages both permanent and intermittentshould be mapped ; stream flow should be recorded and thedirection and flow of underground streams, for example inkarstic areas, should be determined

Boreholes should be used to provide information onpiezometric levels, coefficient of permeability, storage coeffi¬cient, and groundwater chemistry.

Water samples should be collected for laboratory analy¬sis. Special attention should be paid to the determination ofpH and carbon dioxide and sulphate content as factors caus¬

ing corrosion of engineering works. Wherever possible refer¬ence should be made to hydrogeological maps and publica¬tions if they are available.

3.3.4 MAPPING THE RESULTS OF

GEODYNAMIC PROCESSES

The method adopted for the mapping of geodynamicphenomena (2.7) depends on the scale of the map. It is im¬portant to describe not only the features but also the condi¬tions favouring, and the factors causing, their development.It is important to determine not only the extent of thevarious phenomena, but also their frequency of occurrence,die severity and the degree of activity and the rate at whicheach process is going on. An attempt should also be made topredict the future development of the geodynamic phenome¬na. Wherever possible each geodynamic system should beevaluated quantitatively or semi-quantitatively.

At small scales individual phenomena may be mappedfrom aerial photographs and by using other methods ofremote sensing, or by a reconnaissance survey. Quantitativeevaluation may be possible by using the past records of exist¬ing maps, by studying aerial photographs taken at differenttimes in the past, or from historical and other archivalrecords.

At large scales, on the other hand, it is possible to mapthe full geomorphological results of the activity, either bydetailed topographical survey or from aerial photographs.

Detailed surface mapping may be supplemented by us¬

ing boreholes and geophysical methods. The rate of individ¬ual processes may be determined by direct measurement inthe field over a period of time. If the appropriate maps,photographs and archival material are available this aspect isaided by examination of successive editions of large-scalemaps, by aerial photographs taken at intervals of time, andby analysis of other records.

18


terms. These terms should be applied to both the rockmaterial and the rock mass and should include a descriptionof colour, grain size, texture, structure, discontinuities withinthe mass, weathered state, alteration state, strength proper¬ties, permeability and other terms indicating special en¬

gineering characteristics.Adequate description of a rock or soil mass may require

additional information including the dip and strike, or theattitude, of structures and discontinuities, the surface charac¬ter of bedding planes and other discontinuities, the variabili¬ty of structures and discontinuities, the details of the wea¬

thering profile. Of particular importance is the estimation ofthe degree of isotropy and homogeneity of the rock mass.

All these characteristics should be described by usingsemi-quantitative descriptive terms which have been definedfor use in different countries.

3.3.2 MAPPING OF ROCKS AND SOILS FOR

ENGINEERING PURPOSES

From the results of an engineering geological survey, theengineering geologist should aim to produce a map on whichunits are defined by engineering properties. In general theboundaries of these units could be expected to follow litho¬logical boundaries, but the engineering property boundariesmight well bear no relation to either geological structure orto stratigraphical boundaries. An example would be wheredeep weathering has differentially affected various rocktypes. The boundaries of rock and soil units shown on en¬

gineering geological maps of various scales should therefore,as has been stated before (2.4), delimit rock and soil unitswhich are characterized by a certain degree of homogeneityin basic physical properties. Selection of an appropriatemethod for drawing boundaries to mapping units in the fielddepends in the first instance on the purpose for which themapping is being undertaken. In turn, purpose will dictatean appropriate scale and scale will define the basic taxonom-ic or mapping unit which may be the lithological suite, thelithological complex, the lithological type or the engineeringgeological type.

There are suitable methods for mapping the boundariesof each of these units, and these are:1 . Lithological suite. The interpretation of existing geologi¬

cal maps; reconnaissance mapping; photogeology.2. Lithological complex. Areal mapping with facial analysis

to group together genetically related lithological types.3. Lithological type. Detailed areal mapping and pétro¬

graphie investigation.4. Engineering geological type. Detailed investigation of the

physical state of the rock or soil mass within a mappedlithological type.

Methods used in characterizing each of the basic taxonomicor mapping units include :

1. Lithological suite. Evaluation of probable rock behaviourfrom a knowledge of the properties of known rock types.

2. Lithological complex. Geophysical investigations in thefield. Systematic boring and sampling in the field. In situtesting. Laboratory or field-laboratory testing of physicaland index properties. Pétrographie investigation and theevaluation of rock behaviour from a knowledge of theproperties of known rock types.

3. Lithological type. Detailed pétrographie investigation.Geophysical testing in the field. Systematic determinationof index properties in the laboratory. In situ and laborato¬ry testing of mechanical and other rock properties.

4. Engineering geological type. In situ testing of mechanicaland other rock properties. Systematic laboratory testingof physical and mechanical properties.

Basic requirements for both investigation methods andcharacterization methods in delineating mapping units aresummarized in Figure 1 in which the application of themethods to maps at successively larger scales is illustrated.

3.3.3 MAPPING HYDROGEOLOGICAL CONDITIONS

The principal hydrogeological conditions which need to berecorded or monitored in engineering geological mapping areof two types. The first is concerned with surface information,such as springs, seepages, rivers, lakes.

The second relates to subsurface information obtainedfrom existing boreholes and wells or from exploratory bore¬holes made for the purpose. Hydrogeological conditionsshould be quantified wherever possible.

Springs and seepages both permanent and intermittentshould be mapped ; stream flow should be recorded and thedirection and flow of underground streams, for example inkarstic areas, should be determined

Boreholes should be used to provide information onpiezometric levels, coefficient of permeability, storage coeffi¬cient, and groundwater chemistry.

Water samples should be collected for laboratory analy¬sis. Special attention should be paid to the determination ofpH and carbon dioxide and sulphate content as factors caus¬

ing corrosion of engineering works. Wherever possible refer¬ence should be made to hydrogeological maps and publica¬tions if they are available.

3.3.4 MAPPING THE RESULTS OF

GEODYNAMIC PROCESSES

The method adopted for the mapping of geodynamicphenomena (2.7) depends on the scale of the map. It is im¬portant to describe not only the features but also the condi¬tions favouring, and the factors causing, their development.It is important to determine not only the extent of thevarious phenomena, but also their frequency of occurrence,die severity and the degree of activity and the rate at whicheach process is going on. An attempt should also be made topredict the future development of the geodynamic phenome¬na. Wherever possible each geodynamic system should beevaluated quantitatively or semi-quantitatively.

At small scales individual phenomena may be mappedfrom aerial photographs and by using other methods ofremote sensing, or by a reconnaissance survey. Quantitativeevaluation may be possible by using the past records of exist¬ing maps, by studying aerial photographs taken at differenttimes in the past, or from historical and other archivalrecords.

At large scales, on the other hand, it is possible to mapthe full geomorphological results of the activity, either bydetailed topographical survey or from aerial photographs.

Detailed surface mapping may be supplemented by us¬

ing boreholes and geophysical methods. The rate of individ¬ual processes may be determined by direct measurement inthe field over a period of time. If the appropriate maps,photographs and archival material are available this aspect isaided by examination of successive editions of large-scalemaps, by aerial photographs taken at intervals of time, andby analysis of other records.

18

Techniques for acquiring and interpreting data

3.4

3.4.1

Special techniques forengineering geological mapping

PHOTOGEOLOGY

Photo-interpretation is an important aid to engineering geo¬

logical studies as it provides a rapid, relatively cheap andprecise method for the first appraisal of a large area. Thescale adopted is usually 1 : 10,000 to 1 : 30,000. Although themethod may sometimes reveal features which cannot bedetected on the ground, it may also miss important subsur¬face information. It is essential that the results of a photo-geological survey should be supplemented by observationson the ground at selected localities.

Difficulties arise in the discrimination of rock and soiltypes, but these may be overcome by the analysis of resultantlandforms and by differences in tones of colour on thephotographs. The structural elements of the terrain, such as

bedding, faulting and jointing, may be more easily appreciat¬ed and mapped on stereo-pairs of vertical aerial photographsrather than on the ground. In the same way, natural ponds,seepages, springs, swallow holes, submarine springs andother hydrological and hydrogeological features may bemapped. Variations in depth to water table and of the weath¬ered mantle may also be detectable.

Photo-interpretation can aid engineering geologicalstudies in soil mapping, in slope stability, drainage andmaterials surveys, in groundwater studies, and in the selec¬

tion of routes, and the sites for reservoirs and dams.New forms of imaging such as radar, microwave and

infra-red linescan are becoming available to the photogeolo-gist.

Stereoscopic ground photography can be used to studyengineering geological conditions in steep or inaccessiblecliffs, and temporary exposures in engineering excavations.Photogrammetric techniques may be used to quantify theresults.

It should be appreciated that photo-interpretation ishighly skilled work and the best results are obtained by spe¬

cialists working in close co-operation with the geologist.

3.4.2 GEOPHYSICAL METHODS

The techniques of particular use in engineering geologicalmapping are resistivity and seismic methods used both onthe surface and in boreholes. Geophysical measurements ingeneral provide two classes of information :

1. Values for certain physical properties of rocks and soilsand their variation over the map area. Such propertiesmay be correlatable with other properties of the rockmass, such as degree of weathering or jointing, which areof concern to the engineer.

2. Determination of the depth to boundaries between rocksand soils of differing physical properties or to the watertable, and the position of vertical boundaries, for examplefaults, between rock types.

The importance of geophysical methods is that they providea rapid means of indirect and non-destructive assessment ofin situ conditions.

3.4.2.1 Resistivity measurements

The method is based on the measurement of the electricalresistivity of the ground which is dependent primarily on

porosity, fracturing, degree of saturation and the salinity ofthe pore-water. For the method to work effectively theremust be a good contrast between physical properties such as

is provided, for example, by shatter zones of high porosity inigneous and metamorphic rocks, and by weathered rock over¬lying fresh igneous and metamorphic rocks.

A combination of two methods is in common use. Elec¬

trical boring is the determination of the variation in resistivi¬ty with depth below a selected point. It is used to determinedepth to water table, bedrock and other changes in lithology.Electrical profiling depends upon the interpretation in en¬

gineering geological terms of variation in resistivity of theground at a predetermined fixed depth at different positionsalong a traverse. A set of electrical profiles, akin to a patternof boreholes to a standard depth, gives a map of variation inresistivity.

3.4.2.2 Seismic measurements

Density and modulus of deformation of the rock and soilmass determine the velocity of transmission of seismic wavesthrough these media. Seismic velocities can be determined bystandard refraction techniques from the surface, or by shot-firing at various depths in one borehole and recording timesof arrival at corresponding depths in adjacent boreholes. Therefraction technique is used to determine depths to differentrefracting horizons, for example rockhead or base of theweathering zone, and depends on there being an increase invelocity of transmission with depth. This is generally the

case.

The method is useful in outlining areas of fractured orweathered rock, tracing marker horizons, and determiningthe depth to bedrock surfaces particularly beneath alluvium.

3.4.3 BORING AND SAMPLING TECHNIQUES

Boring may be undertaken to provide undisturbed or dis¬

turbed samples of rocks and soils, or to provide a hole for insitu testing and the installation of instruments in the ground.A variety of methods is available including augering, percus¬

sive boring and rotary core drilling.Samples must, as far as possible, be truly representative

of the ground conditions, and must neither be contaminatedby material dislodged from higher in the hole, nor modifiedby the loss of some constituents.

For visual examination and the determination of indexproperties disturbed samples may be all that are required.On the other hand, the determination of the physical proper¬ties of soils and rocks demands undisturbed samples as far as

possible representative of the materials in their natural con¬

dition. Undisturbed soil samples are usually retained in thesample tubes, with the exposed ends waxed and capped fortransport to the laboratory without change in moisture con¬

tent. Rock cores are usually extruded with minimum forceinto specially constructed core boxes; samples may be

wrapped and waxed if required.The frequency with which undisturbed samples are

taken, as well as their diameter and length, are determinedlargely by requirements of the investigation in hand. It isconventional to take an undisturbed sample at each changein lithology, and this is recommended as a minimum require¬ment.

Both the pattern and spacing of boreholes need to be

flexible to take account of the geological conditions, andonly rarely will a predetermined grid of boreholes driven to

19


3.4

3.4.1

Special techniques forengineering geological mapping

PHOTOGEOLOGY

Photo-interpretation is an important aid to engineering geo¬

logical studies as it provides a rapid, relatively cheap andprecise method for the first appraisal of a large area. Thescale adopted is usually 1 : 10,000 to 1 : 30,000. Although themethod may sometimes reveal features which cannot bedetected on the ground, it may also miss important subsur¬face information. It is essential that the results of a photo-geological survey should be supplemented by observationson the ground at selected localities.

Difficulties arise in the discrimination of rock and soiltypes, but these may be overcome by the analysis of resultantlandforms and by differences in tones of colour on thephotographs. The structural elements of the terrain, such as

bedding, faulting and jointing, may be more easily appreciat¬ed and mapped on stereo-pairs of vertical aerial photographsrather than on the ground. In the same way, natural ponds,seepages, springs, swallow holes, submarine springs andother hydrological and hydrogeological features may bemapped. Variations in depth to water table and of the weath¬ered mantle may also be detectable.

Photo-interpretation can aid engineering geologicalstudies in soil mapping, in slope stability, drainage andmaterials surveys, in groundwater studies, and in the selec¬

tion of routes, and the sites for reservoirs and dams.New forms of imaging such as radar, microwave and

infra-red linescan are becoming available to the photogeolo-gist.

Stereoscopic ground photography can be used to studyengineering geological conditions in steep or inaccessiblecliffs, and temporary exposures in engineering excavations.Photogrammetric techniques may be used to quantify theresults.

It should be appreciated that photo-interpretation ishighly skilled work and the best results are obtained by spe¬

cialists working in close co-operation with the geologist.

3.4.2 GEOPHYSICAL METHODS

The techniques of particular use in engineering geologicalmapping are resistivity and seismic methods used both onthe surface and in boreholes. Geophysical measurements ingeneral provide two classes of information :

1. Values for certain physical properties of rocks and soilsand their variation over the map area. Such propertiesmay be correlatable with other properties of the rockmass, such as degree of weathering or jointing, which areof concern to the engineer.

2. Determination of the depth to boundaries between rocksand soils of differing physical properties or to the watertable, and the position of vertical boundaries, for examplefaults, between rock types.

The importance of geophysical methods is that they providea rapid means of indirect and non-destructive assessment ofin situ conditions.

3.4.2.1 Resistivity measurements

The method is based on the measurement of the electricalresistivity of the ground which is dependent primarily on

porosity, fracturing, degree of saturation and the salinity ofthe pore-water. For the method to work effectively theremust be a good contrast between physical properties such as

is provided, for example, by shatter zones of high porosity inigneous and metamorphic rocks, and by weathered rock over¬lying fresh igneous and metamorphic rocks.

A combination of two methods is in common use. Elec¬

trical boring is the determination of the variation in resistivi¬ty with depth below a selected point. It is used to determinedepth to water table, bedrock and other changes in lithology.Electrical profiling depends upon the interpretation in en¬

gineering geological terms of variation in resistivity of theground at a predetermined fixed depth at different positionsalong a traverse. A set of electrical profiles, akin to a patternof boreholes to a standard depth, gives a map of variation inresistivity.

3.4.2.2 Seismic measurements

Density and modulus of deformation of the rock and soilmass determine the velocity of transmission of seismic wavesthrough these media. Seismic velocities can be determined bystandard refraction techniques from the surface, or by shot-firing at various depths in one borehole and recording timesof arrival at corresponding depths in adjacent boreholes. Therefraction technique is used to determine depths to differentrefracting horizons, for example rockhead or base of theweathering zone, and depends on there being an increase invelocity of transmission with depth. This is generally the

case.

The method is useful in outlining areas of fractured orweathered rock, tracing marker horizons, and determiningthe depth to bedrock surfaces particularly beneath alluvium.

3.4.3 BORING AND SAMPLING TECHNIQUES

Boring may be undertaken to provide undisturbed or dis¬

turbed samples of rocks and soils, or to provide a hole for insitu testing and the installation of instruments in the ground.A variety of methods is available including augering, percus¬

sive boring and rotary core drilling.Samples must, as far as possible, be truly representative

of the ground conditions, and must neither be contaminatedby material dislodged from higher in the hole, nor modifiedby the loss of some constituents.

For visual examination and the determination of indexproperties disturbed samples may be all that are required.On the other hand, the determination of the physical proper¬ties of soils and rocks demands undisturbed samples as far as

possible representative of the materials in their natural con¬

dition. Undisturbed soil samples are usually retained in thesample tubes, with the exposed ends waxed and capped fortransport to the laboratory without change in moisture con¬

tent. Rock cores are usually extruded with minimum forceinto specially constructed core boxes; samples may be

wrapped and waxed if required.The frequency with which undisturbed samples are

taken, as well as their diameter and length, are determinedlargely by requirements of the investigation in hand. It isconventional to take an undisturbed sample at each changein lithology, and this is recommended as a minimum require¬ment.

Both the pattern and spacing of boreholes need to be

flexible to take account of the geological conditions, andonly rarely will a predetermined grid of boreholes driven to

19


/

\

: ° I : " \ o I I //// //° ' o ° : « : ! ! ; ! ! ; i0 o " o : i ; ; ! ; / .° \ o : ° o ! ; : / / :

o .o . » : 0 : ; ; : ; ; / / /

o o : o : ; / / ./..' / / / /o o : ° / / / / / : / / ./ ,

o o : » 1 / / / / / .- / / /0 a . 0 /

0 o : o 1 j ; /° o . / /

o « / / .' .° . /

o ' /

.

Map scale: < 1:200,000

Taxonomic units shown on the map: Lithological suites

Attribute of homogeneity: Specific grouping of certainlithological complexes and their spatial arrangement

Methods of delimiting map units: Existing geologicalmaps; reconnaissance mapping; aerial photogeology

Methods of characterizing map units : Evaluation of exist¬ing data

Map scale: 1 : 10,000 to 1 : 200,000

Taxonomic units shown on the map: Lithological com¬plexes

Attribute of homogeneity: Specific grouping of certainlithological types and their spatial arrangement

Methods of delimiting map units: Areal mapping withfacial analysis

Methods of characterizing map units : Boring and samp¬ling ; geophysical and petrographical investigation ; labora¬tory determination of index properties

Description of map units:

+Granitic suite. Multiple granitic intrusionwith remnants of schists comprising granite,granodiorite, amphibolite, paragneiss


Lower Triassic conglomerate complex. Lit¬toral; conglomerates, sandstones and subor¬dinate mudstones

Lower Triassic clastic suite. Conglomerate,sandstone and mudstone complexes

Middle Triassic calcareous suite. Limestone,dolomite and calcareous mudstone com¬plexes (lithostratigraphical Cantal group)

P^^d

Lower Triassic sandstone complex. Flys-choid; calcareous sandstones, mudstonesand subordinate siltstones (lithostratigraphi¬cal Omewa formation)

Lower Triassic mudstone complex. Shallowneritic; mudstones with subordinate sand¬

stones and siltstones

Fig. 1. The effect of scale on the basic requirement for the investigation and characterization of basic engineering geological mapping units.

20


/

\

: ° I : " \ o I I //// //° ' o ° : « : ! ! ; ! ! ; i0 o " o : i ; ; ! ; / .° \ o : ° o ! ; : / / :

o .o . » : 0 : ; ; : ; ; / / /

o o : o : ; / / ./..' / / / /o o : ° / / / / / : / / ./ ,

o o : » 1 / / / / / .- / / /0 a . 0 /

0 o : o 1 j ; /° o . / /

o « / / .' .° . /

o ' /

.

Map scale: < 1:200,000

Taxonomic units shown on the map: Lithological suites

Attribute of homogeneity: Specific grouping of certainlithological complexes and their spatial arrangement

Methods of delimiting map units: Existing geologicalmaps; reconnaissance mapping; aerial photogeology

Methods of characterizing map units : Evaluation of exist¬ing data

Map scale: 1 : 10,000 to 1 : 200,000

Taxonomic units shown on the map: Lithological com¬plexes

Attribute of homogeneity: Specific grouping of certainlithological types and their spatial arrangement

Methods of delimiting map units: Areal mapping withfacial analysis

Methods of characterizing map units : Boring and samp¬ling ; geophysical and petrographical investigation ; labora¬tory determination of index properties


+Granitic suite. Multiple granitic intrusionwith remnants of schists comprising granite,granodiorite, amphibolite, paragneiss


Lower Triassic conglomerate complex. Lit¬toral; conglomerates, sandstones and subor¬dinate mudstones

Lower Triassic clastic suite. Conglomerate,sandstone and mudstone complexes

Middle Triassic calcareous suite. Limestone,dolomite and calcareous mudstone com¬plexes (lithostratigraphical Cantal group)

P^^d

Lower Triassic sandstone complex. Flys-choid; calcareous sandstones, mudstonesand subordinate siltstones (lithostratigraphi¬cal Omewa formation)

Lower Triassic mudstone complex. Shallowneritic; mudstones with subordinate sand¬

stones and siltstones

Fig. 1. The effect of scale on the basic requirement for the investigation and characterization of basic engineering geological mapping units.

20


Map scale: 1 : 5,000 to 1 : 10,000

Taxonomic units shown on the map : Lithological types

Attribute of homogeneity : Mineralogical composition, tex¬

ture and structure

Methods of delimiting map units : Pétrographie investiga¬tion

Methods of characterizing map units: Boring and samp¬

ling; geophysical testing; limited in situ testing; systematiclaboratory testing

Map scale: > 1:5,000

Taxonomic units shown on the map: Engineering geologi¬cal types

Attribute of homogeneity: Uniformity of physical statewithin each lithological type

Methods of delimiting map units: Investigation, for exam¬ple, of degree of weathering, determination of discontinuityfrequency and pattern, strength, consistency

Methods of characterizing map units: Determination ofphysical and mechanical properties

Description of map units :

Light greyish-brown, fine to very fine-grainedthinly bedded micaceous MUDSTONE


Light greyish-brown, fine to very fine¬grained, thinly bedded, closely jointedslightly weathered, micaceous MUDSTONEwhich slakes slowly on exposure, moderate¬ly weak

Dark brown and yellowish-brown, coarse¬grained, medium to thickly bedded cal¬

careous SANDSTONE

Light greyish-brown, fine to very fine¬grained, laminated, extremely closely joint¬ed, moderately to highly weathered,micaceous MUDSTONE which crumbles inthe fingers, very weak

Dark brown, coarse-grained, medium tothickly bedded, with widely spaced joints,moderately to slightly weathered, calcareousSANDSTONE

Yellowish-brown, coarse-grained, mediumbedded, with closely to very closelyspaced joints, sheared, highly weatheredSANDSTONE

21


Map scale: 1 : 5,000 to 1 : 10,000

Taxonomic units shown on the map : Lithological types

Attribute of homogeneity : Mineralogical composition, tex¬

ture and structure

Methods of delimiting map units : Pétrographie investiga¬tion

Methods of characterizing map units: Boring and samp¬

ling; geophysical testing; limited in situ testing; systematiclaboratory testing

Map scale: > 1:5,000

Taxonomic units shown on the map: Engineering geologi¬cal types

Attribute of homogeneity: Uniformity of physical statewithin each lithological type

Methods of delimiting map units: Investigation, for exam¬ple, of degree of weathering, determination of discontinuityfrequency and pattern, strength, consistency

Methods of characterizing map units: Determination ofphysical and mechanical properties


Light greyish-brown, fine to very fine-grainedthinly bedded micaceous MUDSTONE


Light greyish-brown, fine to very fine¬grained, thinly bedded, closely jointedslightly weathered, micaceous MUDSTONEwhich slakes slowly on exposure, moderate¬ly weak

Dark brown and yellowish-brown, coarse¬grained, medium to thickly bedded cal¬

careous SANDSTONE

Light greyish-brown, fine to very fine¬grained, laminated, extremely closely joint¬ed, moderately to highly weathered,micaceous MUDSTONE which crumbles inthe fingers, very weak

Dark brown, coarse-grained, medium tothickly bedded, with widely spaced joints,moderately to slightly weathered, calcareousSANDSTONE

Yellowish-brown, coarse-grained, mediumbedded, with closely to very closelyspaced joints, sheared, highly weatheredSANDSTONE

21


predetermined depths be entirely suitable for engineeringgeological investigations. Likewise, sampling should be dic¬tated rather by the geological conditions than by a rigidsystem.

3.4.4 LABORATORY AND 'IN SITU' TESTING

3.4.4.1 Laboratory tests

Basic properties of rocks and soils may be determined bystandardized laboratory tests.

Properties which are independent of moisture contentinclude: particle size analysis; liquid and plastic limits; bulkdensity, both dry and saturated ; mineral grain specific gravi¬ty; porosity (voids ratio); mineralogy and petrography.

Many of the tests to determine physical propertiesrequire undisturbed samples at their natural moisture con¬tent. They include : consistency ; cohesion and angle of inter¬nal friction; compressibility; permeability; compressivestrength; tensile strength; attrition value; compaction.

In engineering geological mapping, twenty-five to thirtysamples are normally required for the statistical determina¬tion of the characteristics of each engineering geologicaltype.

3.4.4.2 In situ testing

Sophisticated instrumental techniques are available fordown-the-hole in situ determinations of, for example, thedeformation characteristics of rocks and soils, the shearstrength of soils, natural radio-activity, resistivity and spon¬taneous potential, and piezometric pressure.

Pumping-in and pumping-out tests may be carried outin existing boreholes to provide data on the hydrogeologicalcharacteristics of subsurface materials

The walls of boreholes may be observed, and the detailsrecorded, by borehole cameras which may be linked to sur¬

face monitors.Tests not requiring the use of a borehole include deep

sounding tests. In these, static and dynamic penetrometersare used to determine the resistance of the ground to thepenetration of a cone-shaped point. In the static penetrationtest the cone is jacked into the ground causing steady pene¬

tration; a free-falling drop-hammer is used in the dynamictest.

3.5 Analysis and interpretationof data

In carrying out an engineering geological survey of an area,information would have been gathered on all aspects of en¬

gineering geological conditions. The results obtained in thefield and laboratory would include, for example, data on thedistribution and properties of rocks and soils, on ground¬water, and on both geomorphological conditions and geo¬

dynamic processes (2.1). This information would have beenrecorded directly on the field map sheet, in field notebooks,as borehole logs, and as the tabulated results of laboratoryinvestigations.

Analysis of the data involves the selection and groupingof all the available information into those aspects which areconsidered of importance and absolutely necessary for thespecific purposes for which the map is being made, and into

those which are not. The latter information is not processedfurther. At this stage an attempt should be made to assess

the geological reliability of the data. This requires consider¬able geological experience and a sound appreciation of thosegeneral geological principles which may be applied to thearea being mapped. Data that appear to be unreliable afterthis geological assessment should not be included in any fur¬ther processing.

Having selected and grouped the information, thevarious groups may now be arranged in classes. This in¬

volves the use of various geological, engineering geologicaland engineering classifications adopted, for example, for theclassification of rocks and soils according to their variousproperties, for the classification of groundwater and so on.The classification systems used may be those agreed uponinternationally or those adopted by different countries. Clas¬sification is an important step in data processing; it enablesconsiderable quantities of data to be arranged into sets eachof which can be considered homogeneous.

A logical or a statistical approach may be used to assess

the generalized qualitative or quantitative characteristics ofeach homogeneous set of data.

The final step in data processing is the synthesis of gen¬

eralized information on the different individual componentsof the engineering geological conditions in order to deter¬mine and define individual territorial units that are charac¬terized by a certain and specified degree of uniformity intheir engineering geological conditions.

Beside these informal methods based on the skill andexperience of the engineering geologist, computers are nowbeginning to be applied successfully to engineering geologicalmapping. There are three main areas of interest in the use ofcomputers in this field: storage of coded data; statisticalanalysis of data and the correlation of a great number ofvariables; plotting or automatic drawing of computer pro¬duced maps.

3.6 References

Bondarick, G. K. 1971. Osnovy teoriyi ismenchivosti inzhenerno-geologicheskikh svoistv gornikh porod [Principles of the theory ofthe variability of engineering-geological properties of rocks].Moskva, Nedra.

Bondarick,G. K..; Komarov, I. S.; Ferronsku, V. 1967. Poleviemetody inzhenerno-geologischeskikh issledovanii [Field methodsof engineering-geological investigations]. Moskva, Nedra.

Komarov, I. S. 1972. Nakoplenie i obrabotka informatsii pri inzhe-nernogeologischeskikh issledovamach [Acquisition and analysisof information in engineering-geological investigations]. Mosk¬va, Nedra.

Krynine, D.P.; Judd, W.R. 1957. Principles of engineering geo¬

logy andgeotechnics. McGraw-Hill Book Co. 730 p.Lahee, F. H. 1961. Field geology. 6th ed. New York, Harper.Low, J. W. 1957. Geologicalfield methods. New York, Harper.Rengers, N. 1967. Terrestrial photogrammetry : a valuable tool

for engineering geological purposes. Rock mechanics and en¬

gineering geology, vol. 5, p. 150-4.Terzaghi, K.; Peck, R. B. 1967. Soil mechanics in engineering

practice. 2nd ed. New York, Wiley.

22


predetermined depths be entirely suitable for engineeringgeological investigations. Likewise, sampling should be dic¬tated rather by the geological conditions than by a rigidsystem.

3.4.4 LABORATORY AND 'IN SITU' TESTING

3.4.4.1 Laboratory tests

Basic properties of rocks and soils may be determined bystandardized laboratory tests.

Properties which are independent of moisture contentinclude: particle size analysis; liquid and plastic limits; bulkdensity, both dry and saturated ; mineral grain specific gravi¬ty; porosity (voids ratio); mineralogy and petrography.

Many of the tests to determine physical propertiesrequire undisturbed samples at their natural moisture con¬tent. They include : consistency ; cohesion and angle of inter¬nal friction; compressibility; permeability; compressivestrength; tensile strength; attrition value; compaction.

In engineering geological mapping, twenty-five to thirtysamples are normally required for the statistical determina¬tion of the characteristics of each engineering geologicaltype.

3.4.4.2 In situ testing

Sophisticated instrumental techniques are available fordown-the-hole in situ determinations of, for example, thedeformation characteristics of rocks and soils, the shearstrength of soils, natural radio-activity, resistivity and spon¬taneous potential, and piezometric pressure.

Pumping-in and pumping-out tests may be carried outin existing boreholes to provide data on the hydrogeologicalcharacteristics of subsurface materials

The walls of boreholes may be observed, and the detailsrecorded, by borehole cameras which may be linked to sur¬

face monitors.Tests not requiring the use of a borehole include deep

sounding tests. In these, static and dynamic penetrometersare used to determine the resistance of the ground to thepenetration of a cone-shaped point. In the static penetrationtest the cone is jacked into the ground causing steady pene¬

tration; a free-falling drop-hammer is used in the dynamictest.

3.5 Analysis and interpretationof data

In carrying out an engineering geological survey of an area,information would have been gathered on all aspects of en¬

gineering geological conditions. The results obtained in thefield and laboratory would include, for example, data on thedistribution and properties of rocks and soils, on ground¬water, and on both geomorphological conditions and geo¬

dynamic processes (2.1). This information would have beenrecorded directly on the field map sheet, in field notebooks,as borehole logs, and as the tabulated results of laboratoryinvestigations.

Analysis of the data involves the selection and groupingof all the available information into those aspects which areconsidered of importance and absolutely necessary for thespecific purposes for which the map is being made, and into

those which are not. The latter information is not processedfurther. At this stage an attempt should be made to assess

the geological reliability of the data. This requires consider¬able geological experience and a sound appreciation of thosegeneral geological principles which may be applied to thearea being mapped. Data that appear to be unreliable afterthis geological assessment should not be included in any fur¬ther processing.

Having selected and grouped the information, thevarious groups may now be arranged in classes. This in¬

volves the use of various geological, engineering geologicaland engineering classifications adopted, for example, for theclassification of rocks and soils according to their variousproperties, for the classification of groundwater and so on.The classification systems used may be those agreed uponinternationally or those adopted by different countries. Clas¬sification is an important step in data processing; it enablesconsiderable quantities of data to be arranged into sets eachof which can be considered homogeneous.

A logical or a statistical approach may be used to assess

the generalized qualitative or quantitative characteristics ofeach homogeneous set of data.

The final step in data processing is the synthesis of gen¬

eralized information on the different individual componentsof the engineering geological conditions in order to deter¬mine and define individual territorial units that are charac¬terized by a certain and specified degree of uniformity intheir engineering geological conditions.

Beside these informal methods based on the skill andexperience of the engineering geologist, computers are nowbeginning to be applied successfully to engineering geologicalmapping. There are three main areas of interest in the use ofcomputers in this field: storage of coded data; statisticalanalysis of data and the correlation of a great number ofvariables; plotting or automatic drawing of computer pro¬duced maps.

3.6 References

Bondarick, G. K. 1971. Osnovy teoriyi ismenchivosti inzhenerno-geologicheskikh svoistv gornikh porod [Principles of the theory ofthe variability of engineering-geological properties of rocks].Moskva, Nedra.

Bondarick,G. K..; Komarov, I. S.; Ferronsku, V. 1967. Poleviemetody inzhenerno-geologischeskikh issledovanii [Field methodsof engineering-geological investigations]. Moskva, Nedra.

Komarov, I. S. 1972. Nakoplenie i obrabotka informatsii pri inzhe-nernogeologischeskikh issledovamach [Acquisition and analysisof information in engineering-geological investigations]. Mosk¬va, Nedra.

Krynine, D.P.; Judd, W.R. 1957. Principles of engineering geo¬

logy andgeotechnics. McGraw-Hill Book Co. 730 p.Lahee, F. H. 1961. Field geology. 6th ed. New York, Harper.Low, J. W. 1957. Geologicalfield methods. New York, Harper.Rengers, N. 1967. Terrestrial photogrammetry : a valuable tool

for engineering geological purposes. Rock mechanics and en¬

gineering geology, vol. 5, p. 150-4.Terzaghi, K.; Peck, R. B. 1967. Soil mechanics in engineering

practice. 2nd ed. New York, Wiley.

22

Presentation of data on engineeringgeological maps

4

4.1 Introduction

The content of engineering geological maps (2.3.3) and theamount of detail shown on engineering geological conditions(2.1) are determined by the purpose and the scale of the map.It is desirable to keep in mind the following important aimof engineering geological mapping, namely that the compila¬tion of engineering geological maps should be based on thesame general principles regardless of the fact that maps ofdifferent scales are designed to solve problems of differentkinds. This would make it possible to compare directly mapsdrawn at the same scale for different areas, it would alsofacilitate the production of maps of medium to small scale,for example, from maps of large scale without the necessityof any radical changes.

There are many kinds of maps determined by the cri¬teria of purpose, content and scale :

Purpose

Specialpurpose

Multipurpose

AuxiliaryComplementary

Medium

Large

All combinations are possible; for example multipurposemaps may be prepared for a variety of engineering purposescovering many aspects of engineering geology; they may beanalytical or comprehensive and may be prepared at allscales.

The most general or basic type of map is the multi¬purpose comprehensive map on which are presented andevaluated all the principal components of an engineeringgeological environment. This type of map would provideinformation pertinent to many purposes and needs. Tech¬

niques used in the presentation of data on a multipurpose

comprehensive map are also of general application to otherkinds of engineering geological maps. These techniques,considered according to scale, are discussed in detail below.

4.2 Multipurpose maps

Multipurpose maps may be analytical or comprehensive.

4.2.1 ANALYTICAL MULTIPURPOSE MAPS

The content of analytical maps is usually obvious from theirtitle ; for example an analytical map may be a map of intensi¬ty and pattern of jointing, or may show slope angles, orslope stability, or landslides. Thus an analytical multipur¬pose map gives both details of, and evaluates, an individualcomponent of the geological environment for many pur¬

poses.

4.2.2 COMPREHENSIVE MULTIPURPOSE MAPS

On the other hand, comprehensive maps are of two basickinds. They may show on one map sheet all the componentsof the engineering geological environment, or they maydepict on one map sheet those areas which have beengrouped for zoning purposes on the basis of the uniformityof their engineering geological conditions (zoning maps).

4.2.2.1 Small-scale comprehensive multipurpose maps

Small-scale maps of areas in which the engineering geology iswell known can be compiled using available maps, literatureand archival documents. In poorly investigated areas mapsare prepared by photogeological interpretation and recon¬

naissance mapping.Small-scale maps should show mainly the distribution

and character of lithogenetic and lithofacial complexes ofrocks and soils, depth to water table, corrosiveness ofgroundwater and the extent of active geological processeswhich are of importance in engineering geology.

Representation of rocks and soils is the main informa¬tion contained on the map. It is recommended that the surfi-cial deposits and the bedrock should be shown. The upper

23

Presentation of data on engineeringgeological maps

4

4.1 Introduction

The content of engineering geological maps (2.3.3) and theamount of detail shown on engineering geological conditions(2.1) are determined by the purpose and the scale of the map.It is desirable to keep in mind the following important aimof engineering geological mapping, namely that the compila¬tion of engineering geological maps should be based on thesame general principles regardless of the fact that maps ofdifferent scales are designed to solve problems of differentkinds. This would make it possible to compare directly mapsdrawn at the same scale for different areas, it would alsofacilitate the production of maps of medium to small scale,for example, from maps of large scale without the necessityof any radical changes.

There are many kinds of maps determined by the cri¬teria of purpose, content and scale :

Purpose

Specialpurpose

Multipurpose

AuxiliaryComplementary

Medium

Large

All combinations are possible; for example multipurposemaps may be prepared for a variety of engineering purposescovering many aspects of engineering geology; they may beanalytical or comprehensive and may be prepared at allscales.

The most general or basic type of map is the multi¬purpose comprehensive map on which are presented andevaluated all the principal components of an engineeringgeological environment. This type of map would provideinformation pertinent to many purposes and needs. Tech¬

niques used in the presentation of data on a multipurpose

comprehensive map are also of general application to otherkinds of engineering geological maps. These techniques,considered according to scale, are discussed in detail below.

4.2 Multipurpose maps

Multipurpose maps may be analytical or comprehensive.

4.2.1 ANALYTICAL MULTIPURPOSE MAPS

The content of analytical maps is usually obvious from theirtitle ; for example an analytical map may be a map of intensi¬ty and pattern of jointing, or may show slope angles, orslope stability, or landslides. Thus an analytical multipur¬pose map gives both details of, and evaluates, an individualcomponent of the geological environment for many pur¬

poses.

4.2.2 COMPREHENSIVE MULTIPURPOSE MAPS

On the other hand, comprehensive maps are of two basickinds. They may show on one map sheet all the componentsof the engineering geological environment, or they maydepict on one map sheet those areas which have beengrouped for zoning purposes on the basis of the uniformityof their engineering geological conditions (zoning maps).

4.2.2.1 Small-scale comprehensive multipurpose maps

Small-scale maps of areas in which the engineering geology iswell known can be compiled using available maps, literatureand archival documents. In poorly investigated areas mapsare prepared by photogeological interpretation and recon¬

naissance mapping.Small-scale maps should show mainly the distribution

and character of lithogenetic and lithofacial complexes ofrocks and soils, depth to water table, corrosiveness ofgroundwater and the extent of active geological processeswhich are of importance in engineering geology.

Representation of rocks and soils is the main informa¬tion contained on the map. It is recommended that the surfi-cial deposits and the bedrock should be shown. The upper

23


complex of surficial deposits may be shown by light coloursselected according to a standard scheme1 representing theirlithogenetic character. Bedrock may be shown by darkercolours or coloured patterns in which the colour indicatesthe genesis and the pattern the lithology of the rocks andsoils. The age of rocks and soils may be represented bygenerally adopted geological symbols on the map or on thelegend.

Hydrogeological data may be shown by isolines ornumerically as point symbols in a generalized form for eachcomplex of rocks and soils. Position of water tables, estimat¬ed quantity and details of groundwater chemistry may alsobe given.

Surface topography is shown by contours, and pointsymbols may be used to indicate significant geomorphologi¬cal elements.

Selected point symbols may be used to show areas ofactive geodynamic processes, and seismic activity is shownby isoseisms.

On small-scale maps on which zoning is shown a generaluniformity of the main components of the geological envi¬

ronment is the criterion adopted for discriminating individ¬ual zoning units. These could be regions on the basis ofgeotectonic elements, areas determined by macrogeomor-phology, and possibly zones on the basis of uniformity inlithofacial character and structural arrangement.

4.2.2.2 Medium-scale comprehensive multipurpose maps

Medium-scale maps are prepared on the basis of field investi¬gations and mapping supplemented by the use of existingarchival material and any necessary complementary work.The same information should be shown on medium-scalemaps as on small-scale maps but should be presented ingreater detail. Lithological suites may be divided into litho¬logical complexes and, if possible, into even smaller combi¬nations of lithological types. Two or three uppermost rockand soil units may be shown on the map together with alithological description of engineering geological terms.Rock and soil properties may be indicated in the legend.

In determining the depth to which engineering geologi¬cal conditions should be shown, the main purpose as well as

geological complexity will have to be taken into account.As with small-scale maps, the rocks and soils at the

surface may be shown by colour, and underlying complexesmay be shown by distinguishing coloured patterns. If morethan two rock and soil complexes are to be shown differentmethods of three-dimensional representation may be applied(4.5). Gradational values of thickness could be shown bydifferent intensities of the colours used to distinguish variouscomplexes, by variation in thickness of the coloured pat¬terns, by isolines of thickness, or by numbers. Similar varia¬tions in colour or thickness of line in patterns could also beused for indicating different graduation in depth. Depthsmay also be shown by isolines or by numbers.

On medium-scale maps the water table may be repre¬sented by contours and its range of fluctuation indicated bynumbers. In mountainous regions this is not possible anddepth to water table and other features can only be shown bynumbers. Both depths to confined water and piezometriclevels can be shown by contours.

Data on groundwater chemistry should be shown on themap by symbols or numerically.

Surface topography is shown by contours and the actualboundaries and details of geomorphological features can be

mapped. On medium-scale maps areas occupied by geo¬

dynamic features should be delineated and the boundaries ofindividual features should be shown where possible.

On medium-scale maps on which zoning is shown, zonesare discriminated on the basis of the homogeneity and struc¬tural arrangement of rock and soil map units. Where pos¬

sible, smaller areal units may be indicated in which eitherhydrogeological or geodynamic phenomena, or both, areuniform.

4.2.2.3 Large-scale comprehensive multipurpose maps

Large-scale maps are prepared by detailed field investiga¬tions and mapping, using all existing archival material, syste¬

matic subsurface exploratory and geophysical work and fieldand laboratory testing. It is necessary to determine the physi¬cal and mechanical properties of all rock and soil unitsrepresented on the map. Sufficient data may be available topermit statistical analysis of the results.

Lithological and engineering geological rock and soiltypes and their structure and spatial arrangement in depthmay be shown by a combination of colours and colouredpatterns (or simply in black and white). Two or more upper¬most rock and soil units should be shown on the map to¬

gether with a lithological description in engineering geologicalterms. Statistically determined rock and soil properties maybe indicated in the legend.

In deciding the depth to which engineering geologicalconditions should be shown, the main purpose for which themap may serve will have to be taken into account as well as

the complexity of the geology.Different methods available for three-dimensional repre¬

sentation of thickness and depth conditions are dealt with insection 4.5.

On large-scale maps hydrogeological conditions may berepresented at suitable intervals, say 1 m, by isohypses, iso¬

baths and isopiestic lines, with known fluctuations shownnumerically. The results of chemical analyses of groundwatermay be shown numerically or by symbols. Other necessarydata on water conservation areas and other aspects of hydro-geology may be shown.

Surface topograhy is shown by contours, and the actualboundaries and details of geomorphological features can beshown. The actual boundaries of individual geodynamic fea¬

tures, and where possible their internal structures, can beshown on large-scale maps.

Zoning on large-scale maps is based on the homogeneityand structural arrangement of the mapped rock and soilunits, as well as on the uniformity of hydrogeological condi¬tions and geodynamic phenomena.

4.3 Special purpose maps

Special purpose engineering geological maps are preparedfor one specific purpose or provide information on one spe¬

cific aspect of engineering geology. They may be analyticalor comprehensive and are prepared at all scales.

Techniques used for representation of rock and soilunits, hydrogeological conditions as well as geomorphologyand geodynamic features are the same as those used formultipurpose maps (4.2.1 to 4.2.2.3).

1 There is at present no generally recognized international standard scheme of coloursand symbols for use on engineering geological maps However, there is an interna¬tional legend for hydrogeological maps (Unesco, 1970)

24


complex of surficial deposits may be shown by light coloursselected according to a standard scheme1 representing theirlithogenetic character. Bedrock may be shown by darkercolours or coloured patterns in which the colour indicatesthe genesis and the pattern the lithology of the rocks andsoils. The age of rocks and soils may be represented bygenerally adopted geological symbols on the map or on thelegend.

Hydrogeological data may be shown by isolines ornumerically as point symbols in a generalized form for eachcomplex of rocks and soils. Position of water tables, estimat¬ed quantity and details of groundwater chemistry may alsobe given.

Surface topography is shown by contours, and pointsymbols may be used to indicate significant geomorphologi¬cal elements.

Selected point symbols may be used to show areas ofactive geodynamic processes, and seismic activity is shownby isoseisms.

On small-scale maps on which zoning is shown a generaluniformity of the main components of the geological envi¬

ronment is the criterion adopted for discriminating individ¬ual zoning units. These could be regions on the basis ofgeotectonic elements, areas determined by macrogeomor-phology, and possibly zones on the basis of uniformity inlithofacial character and structural arrangement.

4.2.2.2 Medium-scale comprehensive multipurpose maps

Medium-scale maps are prepared on the basis of field investi¬gations and mapping supplemented by the use of existingarchival material and any necessary complementary work.The same information should be shown on medium-scalemaps as on small-scale maps but should be presented ingreater detail. Lithological suites may be divided into litho¬logical complexes and, if possible, into even smaller combi¬nations of lithological types. Two or three uppermost rockand soil units may be shown on the map together with alithological description of engineering geological terms.Rock and soil properties may be indicated in the legend.

In determining the depth to which engineering geologi¬cal conditions should be shown, the main purpose as well as

geological complexity will have to be taken into account.As with small-scale maps, the rocks and soils at the

surface may be shown by colour, and underlying complexesmay be shown by distinguishing coloured patterns. If morethan two rock and soil complexes are to be shown differentmethods of three-dimensional representation may be applied(4.5). Gradational values of thickness could be shown bydifferent intensities of the colours used to distinguish variouscomplexes, by variation in thickness of the coloured pat¬terns, by isolines of thickness, or by numbers. Similar varia¬tions in colour or thickness of line in patterns could also beused for indicating different graduation in depth. Depthsmay also be shown by isolines or by numbers.

On medium-scale maps the water table may be repre¬sented by contours and its range of fluctuation indicated bynumbers. In mountainous regions this is not possible anddepth to water table and other features can only be shown bynumbers. Both depths to confined water and piezometriclevels can be shown by contours.

Data on groundwater chemistry should be shown on themap by symbols or numerically.

Surface topography is shown by contours and the actualboundaries and details of geomorphological features can be

mapped. On medium-scale maps areas occupied by geo¬

dynamic features should be delineated and the boundaries ofindividual features should be shown where possible.

On medium-scale maps on which zoning is shown, zonesare discriminated on the basis of the homogeneity and struc¬tural arrangement of rock and soil map units. Where pos¬

sible, smaller areal units may be indicated in which eitherhydrogeological or geodynamic phenomena, or both, areuniform.

4.2.2.3 Large-scale comprehensive multipurpose maps

Large-scale maps are prepared by detailed field investiga¬tions and mapping, using all existing archival material, syste¬

matic subsurface exploratory and geophysical work and fieldand laboratory testing. It is necessary to determine the physi¬cal and mechanical properties of all rock and soil unitsrepresented on the map. Sufficient data may be available topermit statistical analysis of the results.

Lithological and engineering geological rock and soiltypes and their structure and spatial arrangement in depthmay be shown by a combination of colours and colouredpatterns (or simply in black and white). Two or more upper¬most rock and soil units should be shown on the map to¬

gether with a lithological description in engineering geologicalterms. Statistically determined rock and soil properties maybe indicated in the legend.

In deciding the depth to which engineering geologicalconditions should be shown, the main purpose for which themap may serve will have to be taken into account as well as

the complexity of the geology.Different methods available for three-dimensional repre¬

sentation of thickness and depth conditions are dealt with insection 4.5.

On large-scale maps hydrogeological conditions may berepresented at suitable intervals, say 1 m, by isohypses, iso¬

baths and isopiestic lines, with known fluctuations shownnumerically. The results of chemical analyses of groundwatermay be shown numerically or by symbols. Other necessarydata on water conservation areas and other aspects of hydro-geology may be shown.

Surface topograhy is shown by contours, and the actualboundaries and details of geomorphological features can beshown. The actual boundaries of individual geodynamic fea¬

tures, and where possible their internal structures, can beshown on large-scale maps.

Zoning on large-scale maps is based on the homogeneityand structural arrangement of the mapped rock and soilunits, as well as on the uniformity of hydrogeological condi¬tions and geodynamic phenomena.

4.3 Special purpose maps

Special purpose engineering geological maps are preparedfor one specific purpose or provide information on one spe¬

cific aspect of engineering geology. They may be analyticalor comprehensive and are prepared at all scales.

Techniques used for representation of rock and soilunits, hydrogeological conditions as well as geomorphologyand geodynamic features are the same as those used formultipurpose maps (4.2.1 to 4.2.2.3).

1 There is at present no generally recognized international standard scheme of coloursand symbols for use on engineering geological maps However, there is an interna¬tional legend for hydrogeological maps (Unesco, 1970)

24

Presentation of data on engineering geological maps

4.3.1 ANALYTICAL SPECIAL PURPOSE MAPS

These maps represent individual components of the engineer¬ing geological conditions and evaluate them from the view¬point of one specific purpose. For example, landslides maybe evaluated in the context of urban development in whichthe engineering geological component is the landslide andthe specific purpose for which the map is made is urbandevelopment; other examples involving landslides would belandslides and land reclamation, or landslides and thestability of reservoir slopes. To quote but a few examples,rocks and soils could be considered from the point of view ofindustrial use, of quarrying, of settlement characteristics ofthe ground and of water seepage from natural or artificialreservoirs; each of these combinations would be representedon a single analytical special purpose map.

4.3.2 COMPREHENSIVE SPECIAL PURPOSE MAPS

Comprehensive special purpose maps represent on one mapsheet all the basic components of engineering geological con¬ditions (2.1) and classify and evaluate them from the view¬point of one specific purpose. The specific purpose could beurban development, underground construction or transpor¬tation routes as some examples.

Evaluation for different specific purposes could also bedone on a map of engineering geological zoning by groupingterritorial units on the basis of the uniformity of their en¬

gineering geological conditions. Such a zoning map could bea separate map sheet, or at small scales could be combinedwith the map of engineering geological conditions.

bedrock surface and details of the surficial deposits should ifpossible be shown by any one of several methods: the stripemethod; bedrock contours; point logs of borings; cross-sections (4.6); isometric diagrams; or isopachous lines. Nomethod used should overcrowd the map to the point of il¬

legibility. For showing on medium- and large-scale maps thedepth and thickness of Quaternary deposits with only a fewunits between the ground surface and the bedrock surface,the stripe method is suggested as being particularly useful.

4.6 Engineering geologicalcross-sections

Engineering geological cross-sections are a necessary adjunctto all main types of engineering geological maps. The num¬ber and direction of cross-sections are chosen, taking intoaccount geomorphology and geological structure, to illus¬trate the relationship between the components of the en¬

gineering geological conditions.The horizontal scale of cross-sections should be equal

to, or larger than, the scale of the map. Vertical scale ischosen so that it is possible to show the extent and characterof the uppermost rock and soil units. The depth to which thecross-section is drawn should be directly related to the depthof available boreholes and other excavations.

All information presented on the map should also be

shown on the cross-sections, for example hydrogeologicalconditions, engineering geological zoning, the results of geo¬

dynamic processes and engineering properties of all rock andsoil units. The degree of detail on the cross-section will cor¬respond with the detail shown on the map.

4.4 Interpretative geological maps

General purpose geological maps, even though they have notbeen made specifically for engineering purposes, contain a

great deal of information of value to the engineer. An en¬

gineering geologist, or an engineer with a sound basic knowl¬edge of geology, would be able to interpret such maps inengineering geological terms, but it should be borne in mindthat the resultant interpretative map is not a true engineeringgeological map.

Interpretative geological maps may be provided by sup¬

plementation of geological maps with descriptive informa¬tion in engineering geological terms by using additionallegends on the published map sheet, by separately printednotes or by addition of information to archival copies of anexisting geological map sheet.

4.5 Three-dimensionalrepresentation on maps

Because engineering structures have an influence on the sub¬

surface, and often extend below the ground surface or areconstructed below the surface, three-dimensional representa¬tion on engineering geological maps is desirable. Where sur¬

ficial deposits overlie bedrock it is generally desirable toshow the depth and character of the bedrock surface. Onsmall-scale maps, three-dimensional information can begiven only at points by symbols; in more detailed maps the

4.7 Documentation maps

A documentation map provides a record of sources of infor¬mation used in compiling an engineering geological map.The documentation map should be drawn at the same scale

as the associated engineering geological map, and if there is

no danger of overcrowding the map with symbols the twomaps may be combined on one sheet.

The information recorded on the documentation mapincludes, for example, symbols showing the position, depthand type of individual boreholes; observed or investigatedexposures, pits, quarries and other excavations; wells andsprings. Drill holes should be indicated in which pressure-metric tests and geophysical logging have been done; fromwhich samples for laboratory tests were taken; which weretested by pumping water in or out, as well as those which wereused for observation of the underground water régime. Thelocation of sites used for engineering geological field experi¬ments and geophysical experiments should also be indicated.

Information related to past investigations, photogeologyand archives should also be outlined.

The legend on the documentation map sheet should ex¬

plain all symbols used. The name of the organization whichundertook each investigation, the date and the place whererecords are kept should be shown either on the map or in anaccompanying memoir.

Standard symbols should be used where they are avail¬able.

25

Presentation of data on engineering geological maps

4.3.1 ANALYTICAL SPECIAL PURPOSE MAPS

These maps represent individual components of the engineer¬ing geological conditions and evaluate them from the view¬point of one specific purpose. For example, landslides maybe evaluated in the context of urban development in whichthe engineering geological component is the landslide andthe specific purpose for which the map is made is urbandevelopment; other examples involving landslides would belandslides and land reclamation, or landslides and thestability of reservoir slopes. To quote but a few examples,rocks and soils could be considered from the point of view ofindustrial use, of quarrying, of settlement characteristics ofthe ground and of water seepage from natural or artificialreservoirs; each of these combinations would be representedon a single analytical special purpose map.

4.3.2 COMPREHENSIVE SPECIAL PURPOSE MAPS

Comprehensive special purpose maps represent on one mapsheet all the basic components of engineering geological con¬ditions (2.1) and classify and evaluate them from the view¬point of one specific purpose. The specific purpose could beurban development, underground construction or transpor¬tation routes as some examples.

Evaluation for different specific purposes could also bedone on a map of engineering geological zoning by groupingterritorial units on the basis of the uniformity of their en¬

gineering geological conditions. Such a zoning map could bea separate map sheet, or at small scales could be combinedwith the map of engineering geological conditions.

bedrock surface and details of the surficial deposits should ifpossible be shown by any one of several methods: the stripemethod; bedrock contours; point logs of borings; cross-sections (4.6); isometric diagrams; or isopachous lines. Nomethod used should overcrowd the map to the point of il¬

legibility. For showing on medium- and large-scale maps thedepth and thickness of Quaternary deposits with only a fewunits between the ground surface and the bedrock surface,the stripe method is suggested as being particularly useful.

4.6 Engineering geologicalcross-sections

Engineering geological cross-sections are a necessary adjunctto all main types of engineering geological maps. The num¬ber and direction of cross-sections are chosen, taking intoaccount geomorphology and geological structure, to illus¬trate the relationship between the components of the en¬

gineering geological conditions.The horizontal scale of cross-sections should be equal

to, or larger than, the scale of the map. Vertical scale ischosen so that it is possible to show the extent and characterof the uppermost rock and soil units. The depth to which thecross-section is drawn should be directly related to the depthof available boreholes and other excavations.

All information presented on the map should also be

shown on the cross-sections, for example hydrogeologicalconditions, engineering geological zoning, the results of geo¬

dynamic processes and engineering properties of all rock andsoil units. The degree of detail on the cross-section will cor¬respond with the detail shown on the map.


General purpose geological maps, even though they have notbeen made specifically for engineering purposes, contain a

great deal of information of value to the engineer. An en¬

gineering geologist, or an engineer with a sound basic knowl¬edge of geology, would be able to interpret such maps inengineering geological terms, but it should be borne in mindthat the resultant interpretative map is not a true engineeringgeological map.

Interpretative geological maps may be provided by sup¬

plementation of geological maps with descriptive informa¬tion in engineering geological terms by using additionallegends on the published map sheet, by separately printednotes or by addition of information to archival copies of anexisting geological map sheet.

4.5 Three-dimensionalrepresentation on maps

Because engineering structures have an influence on the sub¬

surface, and often extend below the ground surface or areconstructed below the surface, three-dimensional representa¬tion on engineering geological maps is desirable. Where sur¬

ficial deposits overlie bedrock it is generally desirable toshow the depth and character of the bedrock surface. Onsmall-scale maps, three-dimensional information can begiven only at points by symbols; in more detailed maps the


A documentation map provides a record of sources of infor¬mation used in compiling an engineering geological map.The documentation map should be drawn at the same scale

as the associated engineering geological map, and if there is

no danger of overcrowding the map with symbols the twomaps may be combined on one sheet.

The information recorded on the documentation mapincludes, for example, symbols showing the position, depthand type of individual boreholes; observed or investigatedexposures, pits, quarries and other excavations; wells andsprings. Drill holes should be indicated in which pressure-metric tests and geophysical logging have been done; fromwhich samples for laboratory tests were taken; which weretested by pumping water in or out, as well as those which wereused for observation of the underground water régime. Thelocation of sites used for engineering geological field experi¬ments and geophysical experiments should also be indicated.

Information related to past investigations, photogeologyand archives should also be outlined.

The legend on the documentation map sheet should ex¬

plain all symbols used. The name of the organization whichundertook each investigation, the date and the place whererecords are kept should be shown either on the map or in anaccompanying memoir.

Standard symbols should be used where they are avail¬able.

25


4.8 Explanation and legendThe explanation or legend on the engineering geological mapprovides a guide to the symbols, colours and patterns used inproducing the map. In addition, summary accounts may begiven, for example, of rock and soil properties, hydrogeolog¬ical conditions, geodynamic processes, and the evaluation ofindividual zoning units.

4.9 ReferenceUnesco. 1970. International legendfor hydrogeological maps/'Légende

internationale des cartes hydrogéologiques. Pans, Unesco/IASH,IAH and London, Institute of Geological Sciences. 101 p.

26


4.8 Explanation and legendThe explanation or legend on the engineering geological mapprovides a guide to the symbols, colours and patterns used inproducing the map. In addition, summary accounts may begiven, for example, of rock and soil properties, hydrogeolog¬ical conditions, geodynamic processes, and the evaluation ofindividual zoning units.

4.9 ReferenceUnesco. 1970. International legendfor hydrogeological maps/'Légende

internationale des cartes hydrogéologiques. Pans, Unesco/IASH,IAH and London, Institute of Geological Sciences. 101 p.

26

Examples of engineeringgeological maps

5

5.1 Introduction of engineering geological maps already available in publishedform. Published maps relate to actual geological situationswhich have been mapped in engineering geological terms, in

Maps chosen to illustrate the guidebook have not been a variety of ways. It was felt to be unwise to attempt todrawn specially to illustrate the guidelines laid down in the produce artificial maps to explain the principles of engineer-text, but rather have been selected from the very wide range ing geological mapping set out in the guide.

27

Examples of engineeringgeological maps

5

5.1 Introduction of engineering geological maps already available in publishedform. Published maps relate to actual geological situationswhich have been mapped in engineering geological terms, in

Maps chosen to illustrate the guidebook have not been a variety of ways. It was felt to be unwise to attempt todrawn specially to illustrate the guidelines laid down in the produce artificial maps to explain the principles of engineer-text, but rather have been selected from the very wide range ing geological mapping set out in the guide.

27


5.2 Examples of multipurpose engineering geological maps

5.2.1 MULTIPURPOSE ANALYTICAL MAPS

5.2. 1 . 1 Multipurpose, analytical, small-scale map

Map ofestimated abundance of landslides in the San FranciscoBay Region, California, at a scale of approximately 1 : 170,000.

CommentThe map was prepared as an experimental map to provide afirst approximation of landslide abundance and potential inthe area.

Different parts of the region are ranked on a scale from1 to 6 according to the estimated abundance of landslides inthem. Qualitative ranking is based on the area covered bylandslides estimated on three factors: slope of the groundsurface, rainfall, and rock and soil conditions. Inferred rela¬tions of landsliding to these factors, together with limitedfield knowledge of the actual abundance of landslides insome areas, have been used in the interpretation.

Method of map preparationThe region was divided into the six ranks of landslide abun¬dance by progressively evaluating and ranking the high andlow extremes. Rank 1 represents areas with a very smallamount of landslides, and, at the other extreme, rank 6represents areas that contain a maximum amount of land¬slides in the region. Areas ranked 5 have a lesser, but still verylarge amount of landslides, and areas with a limited amountof landslides, but larger than rank 1 , are assigned to rank 2.

The remaining, intermediate areas are assigned as appro¬priate to ranks 3 and 4.

Rank 1 is defined as areas that receive less than 10 in(255 mm) of mean annual precipitation or have slopes ofless than 5° (determined from 1 : 500,000 scale topographic

map with 500 ft (150 m) contour interval). These criteriaindicate a very small amount of landslides, because land¬slides are rare in areas with less than 10 in (255 mm) ofprecipitation, and review of a limited number of reports andconsultation with other geologists indicates that few land¬slides occur on slopes of less than 5Q (Radbruch, 1970,

p. 4-6). Because of the large contour interval on the mapfrom which slopes were determined and the small scale of thefinal map, sea cliff areas and hilly areas with less than 500 ft(150 m) relief may locally contain abundant landslides,although shown on the map as rank 1 .

Ranking of the remaining region is based largely on thedistribution of earth materials. For this purpose the geologicunits in the region that are shown on the 1 : 250,000 scale

Jenkins edition of the Geologic Map of California weregrouped into eight general classes of earth materials. Theclasses were selected to have as similar landslide characteris¬tics as possible, using readily available literature on land¬slides in the region as a guide. Major differences in landslidescharacteristics within individual classes of earth materialsresulting from varying topography or bedrock type or struc¬ture are used in the ranking where the needed information is

available.This example has been redrawn from a part of

D. H. Radbruch and C. M. Wentworth, Estimated RelativeAbundance of Landslides in the San Francisco Bay Region,California, 1971, United States Department of the Interior,Geological Survey (San Francisco Bay Region Environmentand Resources Planning Study, Basic Data Contribution 11).

28


5.2 Examples of multipurpose engineering geological maps

5.2.1 MULTIPURPOSE ANALYTICAL MAPS

5.2. 1 . 1 Multipurpose, analytical, small-scale map

Map ofestimated abundance of landslides in the San FranciscoBay Region, California, at a scale of approximately 1 : 170,000.

CommentThe map was prepared as an experimental map to provide afirst approximation of landslide abundance and potential inthe area.

Different parts of the region are ranked on a scale from1 to 6 according to the estimated abundance of landslides inthem. Qualitative ranking is based on the area covered bylandslides estimated on three factors: slope of the groundsurface, rainfall, and rock and soil conditions. Inferred rela¬tions of landsliding to these factors, together with limitedfield knowledge of the actual abundance of landslides insome areas, have been used in the interpretation.

Method of map preparationThe region was divided into the six ranks of landslide abun¬dance by progressively evaluating and ranking the high andlow extremes. Rank 1 represents areas with a very smallamount of landslides, and, at the other extreme, rank 6represents areas that contain a maximum amount of land¬slides in the region. Areas ranked 5 have a lesser, but still verylarge amount of landslides, and areas with a limited amountof landslides, but larger than rank 1 , are assigned to rank 2.

The remaining, intermediate areas are assigned as appro¬priate to ranks 3 and 4.

Rank 1 is defined as areas that receive less than 10 in(255 mm) of mean annual precipitation or have slopes ofless than 5° (determined from 1 : 500,000 scale topographic

map with 500 ft (150 m) contour interval). These criteriaindicate a very small amount of landslides, because land¬slides are rare in areas with less than 10 in (255 mm) ofprecipitation, and review of a limited number of reports andconsultation with other geologists indicates that few land¬slides occur on slopes of less than 5Q (Radbruch, 1970,

p. 4-6). Because of the large contour interval on the mapfrom which slopes were determined and the small scale of thefinal map, sea cliff areas and hilly areas with less than 500 ft(150 m) relief may locally contain abundant landslides,although shown on the map as rank 1 .

Ranking of the remaining region is based largely on thedistribution of earth materials. For this purpose the geologicunits in the region that are shown on the 1 : 250,000 scale

Jenkins edition of the Geologic Map of California weregrouped into eight general classes of earth materials. Theclasses were selected to have as similar landslide characteris¬tics as possible, using readily available literature on land¬slides in the region as a guide. Major differences in landslidescharacteristics within individual classes of earth materialsresulting from varying topography or bedrock type or struc¬ture are used in the ranking where the needed information is

available.This example has been redrawn from a part of

D. H. Radbruch and C. M. Wentworth, Estimated RelativeAbundance of Landslides in the San Francisco Bay Region,California, 1971, United States Department of the Interior,Geological Survey (San Francisco Bay Region Environmentand Resources Planning Study, Basic Data Contribution 11).

28

Examples of engineering geological maps

LegendLANDSLIDE ABUNDANCE RANKS

I ' I Least abundant

u

m

Ranking is qualitative, based on estimates and extra¬polation from available data. Specific safety orhazard for construction is not shown. Landslidedistribution within individual map units may not beuniform: parts of the highest ranked units lacklandslides, and parts of the lowest ranked unitscontain landslides. Hilly parts of unit 1 may containabundant landslides

Most abundant

Approximate contact between map units

Fault, approximately located, marking zone of possiblesheared or shattered rock not represented in the rank¬ing but suscepuble to landsliding. Not shown whereconcealed beneath thick overlying deposits or water

29


5.2. 1 .2 Multipurpose, analytical, medium-scale map

Map of landslide susceptibility, San Mateo County, California,at a scale of 1 : 54,500.

Comment

This map sheet provides a more detailed appraisal of land¬slide susceptibility than the smaller-scale map 5.2.1.1. A veryfull explanation is published on the map sheet, includingnotes on how to use the map, discussion of factors affectinglandslide distribution and a slope intervals chart. The presentmap was compiled from the existing geological and landslidemaps and specially produced slope map. Mapping proce¬dures are discussed. A table gives the landslide failure recordfor the rock units cropping out in San Mateo County.

It is concluded that this slope stability map provides aneasily read analysis of selected geological factors that beardirectly on the problem of landsliding within the county.

The map has been redrawn from part of E. E. Brabb,E. H. Pampeyan and M. G. Bonilla, Landslide Susceptibilityin San Mateo County, California, 1972, United StatesDepartment of the Interior, Geological Survey (Miscel¬laneous Field Studies Map MF-360) (San Francisco BayRegion Environment and Resources Planning Study, BasicData Contribution 43).

Legend

Least

Most

II Areas least susceptible to landsliding. VeryI I few small landslides have formed in these

* areas. Formation of large landslides ispossible but unlikely, except during earth¬

quakes. Slopes generally less than 15 per cent, but mayinclude small areas of steep slopes that could havehigher susceptibility. Includes some areas with 30 percent to more than 70 per cent slopes that seem to beunderlain by stable rock units. Additional slopestability problems; some of the areas may be more sus¬ceptible to landsliding if they are overlain by thick de¬posits of soil, slopewash or ravine fill. Rockfalls mayalso occur on steep slopes. Also includes areas alongcreeks, rivers, sloughs and lakes that may fail by land-sliding during earthquakes. If area is adjacent to areawith higher susceptibility, a landslide may encroachinto the area, or the area may fail if a landslide under¬cuts it, such as the flat area adjacent to sea cliffs.

nLow susceptibility to landsliding. Severalsmall landslides have formed in theseareas and some of these have caused ex¬tensive damage to homes and roads. A few

large landslides may occur. Slopes vary from 5-15 percent for unstable rock units to more than 70 per centfor rock units that seem to be stable. The statementsabout additional slope stability problems mentioned inI above apply in this category.

inModerate susceptibility to landsliding.Many small landslides have formed inthese areas and several of these havecaused extensive damage to homes and

roads. Some large landslides likely. Slopes generallygreater than 30 per cent but includes some slopes 15-30per cent in areas underlain by unstable rock units. See Ifor additional slope stability problems.

mModerately high susceptibility to landslid¬ing. Slopes all greater than 30 per cent.These areas are mostly in undevelopedparts of the county. Several large lan-

slides likely. See I for additional slope stability prob¬lems.

I High susceptibility to landsliding. Slopesall greater than 30 per cent. Many large andsmall landslides may form. These areas aremostly in undeveloped parts of the county.

See I for additional slope stability problems.

"21Very high susceptibility to landsliding.Slopes all greater than 30 per cent. Devel¬opment of many large and small landslidesis likely. Slopes all greater than 30 per

cent. The areas are mainly in undeveloped parts of thecounty. See I for additional slope stability problems.

II Highest susceptibility to landsliding. Con-L I sists of landslide and possible landslide de-

I posits. No small landslide deposits areshown. Some of these areas may be rela¬

tively stable and suitable for development, whereas oth¬ers are active and causing damage to roads, houses andother cultural features.

Definitions: Large landslide more than 500 ft (150 m) in maxi¬mum dimension; small landslide 50 to 500 ft (15 to 150 m) inmaximum dimension.

30


5.2. 1 .2 Multipurpose, analytical, medium-scale map

Map of landslide susceptibility, San Mateo County, California,at a scale of 1 : 54,500.

Comment

This map sheet provides a more detailed appraisal of land¬slide susceptibility than the smaller-scale map 5.2.1.1. A veryfull explanation is published on the map sheet, includingnotes on how to use the map, discussion of factors affectinglandslide distribution and a slope intervals chart. The presentmap was compiled from the existing geological and landslidemaps and specially produced slope map. Mapping proce¬dures are discussed. A table gives the landslide failure recordfor the rock units cropping out in San Mateo County.

It is concluded that this slope stability map provides aneasily read analysis of selected geological factors that beardirectly on the problem of landsliding within the county.

The map has been redrawn from part of E. E. Brabb,E. H. Pampeyan and M. G. Bonilla, Landslide Susceptibilityin San Mateo County, California, 1972, United StatesDepartment of the Interior, Geological Survey (Miscel¬laneous Field Studies Map MF-360) (San Francisco BayRegion Environment and Resources Planning Study, BasicData Contribution 43).

Legend

Least

Most

II Areas least susceptible to landsliding. VeryI I few small landslides have formed in these

* areas. Formation of large landslides ispossible but unlikely, except during earth¬

quakes. Slopes generally less than 15 per cent, but mayinclude small areas of steep slopes that could havehigher susceptibility. Includes some areas with 30 percent to more than 70 per cent slopes that seem to beunderlain by stable rock units. Additional slopestability problems; some of the areas may be more sus¬ceptible to landsliding if they are overlain by thick de¬posits of soil, slopewash or ravine fill. Rockfalls mayalso occur on steep slopes. Also includes areas alongcreeks, rivers, sloughs and lakes that may fail by land-sliding during earthquakes. If area is adjacent to areawith higher susceptibility, a landslide may encroachinto the area, or the area may fail if a landslide under¬cuts it, such as the flat area adjacent to sea cliffs.

nLow susceptibility to landsliding. Severalsmall landslides have formed in theseareas and some of these have caused ex¬tensive damage to homes and roads. A few

large landslides may occur. Slopes vary from 5-15 percent for unstable rock units to more than 70 per centfor rock units that seem to be stable. The statementsabout additional slope stability problems mentioned inI above apply in this category.

inModerate susceptibility to landsliding.Many small landslides have formed inthese areas and several of these havecaused extensive damage to homes and

roads. Some large landslides likely. Slopes generallygreater than 30 per cent but includes some slopes 15-30per cent in areas underlain by unstable rock units. See Ifor additional slope stability problems.

mModerately high susceptibility to landslid¬ing. Slopes all greater than 30 per cent.These areas are mostly in undevelopedparts of the county. Several large lan-

slides likely. See I for additional slope stability prob¬lems.

I High susceptibility to landsliding. Slopesall greater than 30 per cent. Many large andsmall landslides may form. These areas aremostly in undeveloped parts of the county.

See I for additional slope stability problems.

"21Very high susceptibility to landsliding.Slopes all greater than 30 per cent. Devel¬opment of many large and small landslidesis likely. Slopes all greater than 30 per

cent. The areas are mainly in undeveloped parts of thecounty. See I for additional slope stability problems.

II Highest susceptibility to landsliding. Con-L I sists of landslide and possible landslide de-

I posits. No small landslide deposits areshown. Some of these areas may be rela¬

tively stable and suitable for development, whereas oth¬ers are active and causing damage to roads, houses andother cultural features.

Definitions: Large landslide more than 500 ft (150 m) in maxi¬mum dimension; small landslide 50 to 500 ft (15 to 150 m) inmaximum dimension.

30


SAN GREGORIUSTATE BEACH

POMPON 10STATE BEACH

PESCADEROSTATE BEACH

31


5.2.2 MULTIPURPOSE COMPREHENSIVE MAPS

5.2.2.1 Multipurpose, comprehensive, small-scale map

Engineering geological map of the Zvolen area (Czecho¬slovakia) at a scale of 1 : 200,000.

LegendOrientation data on the depth of groundwater level(in metres).

4 Important springs (wells) of mineral water

*: Wider protection zones of groundwater utilized for'..,.* spas

N''

N\

(_ Corrosiveness of groundwater

H^Ô^V Landslides

V Extensive gully erosion

Dm,Vh

Ce.Dg

Important faults : (a) verified ; (b) assumed

Boundaries of lithological complexes :

(a) at the surface;

(b) under Quaternary deposits

Boundaries of engineering-geological areas

Boundaries of engineering-geological zones

Symbols for zones

Symbols for areas

Proluvial cones

32

Comment


The map was prepared for the purposes of regional andland-use planning.

Basic engineering geological data on rocks, groundwaterand geodynamic phenomena are represented, and on thebasis of their uniformity engineering geological areas andzones are delimited.

Rocks and soils are divided into lithological suites andcomplexes. Colours are used for the representation of litho¬logical character and patterns for the lithology of Quater¬nary surficial materials (in ochre) and pre-Quatemary base¬

ment (in grey). Quaternary deposits are shown only wherethicker than 3 m. The age of rocks is shown only in thelegend by geological symbols.

Hydrogeological conditions are represented in a gener¬

alized form for each complex of rocks and soils by numerical

symbols in blue colour. Point symbols in red are used toshow areas of technically important geodynamic phenomena(e.g. landslides, gully erosion, karst phenomena).

The method of zoning is applied to delimit differenttypes of engineering geological areas and zones. The discrim¬ination of areas is based on the uniformity of individualregional geomorphological units, and zones are delimited onthe basis of the general character and structural arrangementof hthological complexes.

The illustration is a small part of a map by R. Ondrasikand M. Matula (Czechoslovakia), at a scale of 1 : 200,000.

I GENETIC-LITHOLOGICAL CLASSIFICATION II. ENGINEERING CLASSIFICATION

Age Lithologicalsuites

Symbols Lithological complexes Ai = solid rocks, A2 = semisolid rocks,B = gravelly soils, C = sandy soils,D = cohesive soils, E = unsuitable soils(classiñcation according to CSN BuildingStandard)

Quaternary

Neogene

Mesozoic

Palaeozoic

Surficialdeposits

Molassesuite

Postero-geneticneovolcanites

Limestone-dolomitesuite

Lowerterrigenoussuite

Variscangranitoidintrusions

dQ3-4

1Q3-4

prQ2-3

'N2-Q

,N2

ß

a

'-

ldT2

Qti

Y

... .

'

::;::-:.;-- - - - -

J::ü:

^:::::

r

KiWe

Slopewash sediments

Fluvial sediments on the(a) flood plain(b) terraces

Sediments in proluvial cones

Chemical sediments

Freshwater lacustrine andlacustrine fluvial complex

Neovolcanic basalts

Neovolcanic andésites

Volcanic-lacustrine stratifiedandesitic tuffs and tufñtes

Shallow-neritic calcareouscomplex

Littoral quartziticcomplex

Granitoids

D = loams to stony loams(B = stony debris, talus)

B = sandy and loamy gravels,C = loamy sands, D = sandy loams(E = muddy soils)

B = loamy gravels, D = sandy andstony loams

A2 = travertine

B = loamy gravels, C = loamysands, D = sandy and silty clays

A 1 = basalt, Aj = tuffs

Aj = andesites,B2 = tuffs (propylitized andésites)

A2 = stratified tuffs, tuffites(A 1 = andésite), B = gravels(D = clays)

A, = limestones, dolomites

A, = quartzite (conglomerate),A2 = shales

A, =granodiorite to quartzdiorite

(continued overleaf)

33


5.2.2.1 continued

III. ENGINEERING-GEOLOGICAL CHARACTERISTICS

For rock and soil material (in laboratory)

Symbols Main lithologicaltypes

dQ3-4 Sandy to clayeyloam

1Q3-4 Sandy loamSandy gravels

Dry bulkdensityg cm"3

1.53-1.79

1.50-1.651.80-1.90

Porosity%

35-58

35-45

Uniaxialcompressive

strengthkgf cm "MO1

0.0055

Indentationhardness

(Srejner)kgfmm~2

Modulus ofdeformationEkgf cm-2 10s

Durability

Soften, swell, not frostresistant

Not frost resistant

,rQ2-3 Sandy loams andstony-loamy soils

N2-Q

iN2

ß

a.

tu«

ldT2

Qti

y

Travertine

Loamy gravelsSandy clays, clays

BasaltsBasaltic tuffs

AndésitesBlock and agglom¬erate stuffs

Tuffs

Tuffites

LimestonesDolomites

Quartzites

Granodiontes andquartz-diorites

1.60-1.95

1.50-1.75

2.85-2.95

2.67-2.711.83-2.12

1.30-1.70

1.68-1.85

2.70-2.732.71-2.82

2.53-2.58

2.62-2.70

1-10

30-35

1.5-3.0

1.5-4.518-33

30-40

29-37

0.23-1.390.68-3.79

3.0-4.0

1.1-2.7

1-3

19-25

15-231.6-3

1-2.5

1-1.15

7-146-15

10-14

12-17

150-190

700-900

500-700

50-80

200-300120-400

380-420

270-600

6-8

5-7

0.4-0.8

0.03-563-6

3-3.4

0.4-0.6

Slightly soluble

Swell, soften

Very stableSlightly affected by slakir

StableStable

Variable, not frostresistant, slake

Stable

Stable

Stable

34


5.2.2.1 continued

III. ENGINEERING-GEOLOGICAL CHARACTERISTICS

For rock and soil material (in laboratory)

Symbols Main lithologicaltypes

dQ3-4 Sandy to clayeyloam

1Q3-4 Sandy loamSandy gravels

Dry bulkdensityg cm"3

1.53-1.79

1.50-1.651.80-1.90

Porosity%

35-58

35-45

Uniaxialcompressive

strengthkgf cm "MO1

0.0055

Indentationhardness

(Srejner)kgfmm~2

Modulus ofdeformationEkgf cm-2 10s

Durability

Soften, swell, not frostresistant

Not frost resistant

,rQ2-3 Sandy loams andstony-loamy soils

N2-Q

iN2

ß

a.

tu«

ldT2

Qti

y

Travertine

Loamy gravelsSandy clays, clays

BasaltsBasaltic tuffs

AndésitesBlock and agglom¬erate stuffs

Tuffs

Tuffites

LimestonesDolomites

Quartzites

Granodiontes andquartz-diorites

1.60-1.95

1.50-1.75

2.85-2.95

2.67-2.711.83-2.12

1.30-1.70

1.68-1.85

2.70-2.732.71-2.82

2.53-2.58

2.62-2.70

1-10

30-35

1.5-3.0

1.5-4.518-33

30-40

29-37

0.23-1.390.68-3.79

3.0-4.0

1.1-2.7

1-3

19-25

15-231.6-3

1-2.5

1-1.15

7-146-15

10-14

12-17

150-190

700-900

500-700

50-80

200-300120-400

380-420

270-600

6-8

5-7

0.4-0.8

0.03-563-6

3-3.4

0.4-0.6

Slightly soluble

Swell, soften

Very stableSlightly affected by slakir

StableStable

Variable, not frostresistant, slake

Stable

Stable

Stable

34


For rock and soil complexes (in situ)

Ease ofexcavation

2-4 Thickness 1-9 m, fragmentary debris at the base, very low permeability, without permanent groundwater table, much gully erosion andlandsliding used for brick materials, impervious materials for dams.

1-3 (a) thickness up to 3 m, permeable with permanent continuous groundwater table3-4 (b) thickness up to 1 1 m, slightly permeable (10~4 to 10"3 m/s), without a permanent water table; suitable as fill material

Conical forms; coarse alternating with fine grain material

5 Dome-shaped bodies, stratified structure, open fissures, slightly permeable along fissures and cavities, slightly soluble in water; used forconstruction purposes

4 Cross-bedded sandy gravels and sands with alternating silty clays and clays; lateral transitions and wedging out. Sands and gravels are dense2-3 and slightly to moderately permeable; suitable for fills, locally may be suitable for concrete. Lenticles of cohesive soils are well consolidated,

slightly permeable to effectively impermeable; used for brick making

7 Outliers and remnants of lava flows several metres to tens of metres thick, predominant prismatic jointing. Homogeneous, except marginally.3-5 Intense weathering to several metres, moderately permeable along fissures. Suitable for building stone and crushed aggregates. Irregular

bodies of ashy to coarse-clastic tuffs, very heterogeneous, permeable along fissures and through pores. Suitable for light construction material

6-7 (a) irregular andesitic bodies several to 100 m thick, homogeneous except at the margins, predominantly prismatic jointing, frequent5-7 tectonic disturbance, sometimes propylitized. Fissure permeability. Suitable as a construction material

(b) tuffs tens to hundreds of metres thick, very heterogeneous tuffs and agglomerates, variably cemented, permeable through pores and along joints. Of limited use as a construction material

5-6 Tens to hundreds of metres thick irregular horizons of chaotic and stratified tuffs alternating with tuffites of varied grain size and degree ofheterogeneity. Irregular jointing and frequent selective weathering. Permeable through pores and fissures. Of limited use as a constructionmaterial

5-6 Thick to massive bedded relatively homogeneous limestones and dolomites. Limestones are highly karstilied and highly peimeable. Used as

4-6 a construction material; purer horizons are used for lime productionMassive dolomites with intercalations of shale and limestone are tectonically disturbed. Weathered to various depths to dolomite sandcontaining dolomite fragments Locally used as fill material

4-6 Thickly bedded to massive quartzites with horizons of sencitic and chlontic shales, dynamometamorphosed to a varying degree. Weatheredto a fine rubble. Permeable in tectonically disturbed zones. A suitable material for crushed aggregates

Massive, homogeneous, in places tectonically disturbed and dynamometamorphosed. Polyhedral jointing. Permeable along fissures anddisturbed zones. A suitable construction material


35


For rock and soil complexes (in situ)

Ease ofexcavation

2-4 Thickness 1-9 m, fragmentary debris at the base, very low permeability, without permanent groundwater table, much gully erosion andlandsliding used for brick materials, impervious materials for dams.

1-3 (a) thickness up to 3 m, permeable with permanent continuous groundwater table3-4 (b) thickness up to 1 1 m, slightly permeable (10~4 to 10"3 m/s), without a permanent water table; suitable as fill material

Conical forms; coarse alternating with fine grain material

5 Dome-shaped bodies, stratified structure, open fissures, slightly permeable along fissures and cavities, slightly soluble in water; used forconstruction purposes

4 Cross-bedded sandy gravels and sands with alternating silty clays and clays; lateral transitions and wedging out. Sands and gravels are dense2-3 and slightly to moderately permeable; suitable for fills, locally may be suitable for concrete. Lenticles of cohesive soils are well consolidated,

slightly permeable to effectively impermeable; used for brick making

7 Outliers and remnants of lava flows several metres to tens of metres thick, predominant prismatic jointing. Homogeneous, except marginally.3-5 Intense weathering to several metres, moderately permeable along fissures. Suitable for building stone and crushed aggregates. Irregular

bodies of ashy to coarse-clastic tuffs, very heterogeneous, permeable along fissures and through pores. Suitable for light construction material

6-7 (a) irregular andesitic bodies several to 100 m thick, homogeneous except at the margins, predominantly prismatic jointing, frequent5-7 tectonic disturbance, sometimes propylitized. Fissure permeability. Suitable as a construction material

(b) tuffs tens to hundreds of metres thick, very heterogeneous tuffs and agglomerates, variably cemented, permeable through pores and along joints. Of limited use as a construction material

5-6 Tens to hundreds of metres thick irregular horizons of chaotic and stratified tuffs alternating with tuffites of varied grain size and degree ofheterogeneity. Irregular jointing and frequent selective weathering. Permeable through pores and fissures. Of limited use as a constructionmaterial

5-6 Thick to massive bedded relatively homogeneous limestones and dolomites. Limestones are highly karstilied and highly peimeable. Used as

4-6 a construction material; purer horizons are used for lime productionMassive dolomites with intercalations of shale and limestone are tectonically disturbed. Weathered to various depths to dolomite sandcontaining dolomite fragments Locally used as fill material

4-6 Thickly bedded to massive quartzites with horizons of sencitic and chlontic shales, dynamometamorphosed to a varying degree. Weatheredto a fine rubble. Permeable in tectonically disturbed zones. A suitable material for crushed aggregates

Massive, homogeneous, in places tectonically disturbed and dynamometamorphosed. Polyhedral jointing. Permeable along fissures anddisturbed zones. A suitable construction material


35


5.2.2.1 continued

AREAS ZONES

Type Geological conditionsof the ground

Hydrogeologicalconditions

Present geodynamicprocesses

CeAreas of the volcanic high¬lands

Young and variegated moun¬tainous landscape, formed bythe destruction of originalstratovolcanic forms due todifferencial neotectonic move¬ments and erosion

DmZone of slope-wash depositson magmaticand metamor¬phic rocks

Loamy slopewash soils 2-7 mthick. In the substratum thereare solid and semi-solid,slightly compressible volcanicand pyroclastic rocks

Very slightly water-bearing topractically dry

Intense slope erosion in ero¬

sive furrows and gullies

DgAreas of intramountain basins

Tectonically originatedregional depressions, in whichselective erosion and accumu¬lation of soft Pliocene andQuaternary sediments condi¬tioned moderate to flat formsof landscape/large river flood-plains and terraces dominat¬ing

FuZone of flood-plain alluvialdeposits

NkZone of pre-Quaternaryalternatingcohesive anduncohesive sedi¬

ments

Coarse-grained gravels, sandygravels, sands and sandy toclayey loams. Large riversmay also have sapropelic fillsin abandoned river branchesand depressions. Thickness ofalluvium 5-1 1 m

Gravel deposits are highlysaturated. The groundwaterlevel is at a depth of 5 m.Large areas often flood at highgroundwater levels

Washing out of the bankscauses small slope failures insome places

Moderately compacted Plio¬cene gravels, with silty-clayeybond, and weakly consoli¬dated Pliocene clays of higherplasticity

On the gTavelly Pliocenecomplex abundant small hill¬side springs may occur onslopes

Intensive slope erosion in theform of deep furrows. Fre¬quent small slides at contactswith tuffites

Note. In this table the characteristics for only two selected types of areas and three types of zones are presented as an example.

36


5.2.2.1 continued

AREAS ZONES

Type Geological conditionsof the ground

Hydrogeologicalconditions

Present geodynamicprocesses

CeAreas of the volcanic high¬lands

Young and variegated moun¬tainous landscape, formed bythe destruction of originalstratovolcanic forms due todifferencial neotectonic move¬ments and erosion

DmZone of slope-wash depositson magmaticand metamor¬phic rocks

Loamy slopewash soils 2-7 mthick. In the substratum thereare solid and semi-solid,slightly compressible volcanicand pyroclastic rocks

Very slightly water-bearing topractically dry

Intense slope erosion in ero¬

sive furrows and gullies

DgAreas of intramountain basins

Tectonically originatedregional depressions, in whichselective erosion and accumu¬lation of soft Pliocene andQuaternary sediments condi¬tioned moderate to flat formsof landscape/large river flood-plains and terraces dominat¬ing

FuZone of flood-plain alluvialdeposits

NkZone of pre-Quaternaryalternatingcohesive anduncohesive sedi¬

ments

Coarse-grained gravels, sandygravels, sands and sandy toclayey loams. Large riversmay also have sapropelic fillsin abandoned river branchesand depressions. Thickness ofalluvium 5-1 1 m

Gravel deposits are highlysaturated. The groundwaterlevel is at a depth of 5 m.Large areas often flood at highgroundwater levels

Washing out of the bankscauses small slope failures insome places

Moderately compacted Plio¬cene gravels, with silty-clayeybond, and weakly consoli¬dated Pliocene clays of higherplasticity

On the gTavelly Pliocenecomplex abundant small hill¬side springs may occur onslopes

Intensive slope erosion in theform of deep furrows. Fre¬quent small slides at contactswith tuffites

Note. In this table the characteristics for only two selected types of areas and three types of zones are presented as an example.

36


ENGINEERING-GEOLOGICAL CONDITIONS FOR CONSTRUCTION WORKS

Excavations andcuttings

Fill construction Structural foundations Roads Buildingmaterials

Cuttings and side-slopecuts will mainly beexcavated in slopewashdeposits and the under¬lying weathered rocks;ground water issuingfrom the slope is easilycollected and drainedfrom the site

The construction of largerfills may lead to slope fail¬ure. Use of a combination ofhalf fill-half cut would beadvantageous

Foundation conditions are verygood. The only serious problemis the question of ensuringslope stability during construc¬tion

When determining the line ofroads and railways difficultiesarise because of the effect ofthe gullies, and the needfor good drainage to maintainstability

Brick clays

As a rule foundationexcavations have to bemade below ground¬water level. In deeperexcavations in gravelslarge influxes of water

Does not cause difficulties,but strongly compressiblenon-load-bearing sludgyand putrified muddy accu¬

mulations in oxbow lakesand the fringes of alluvialcones require attention

In foundation of buildings withcellars difficulties are caused bythe high water table. Necessityof installing waterproofing(uplift pressure), in some cases

precautions againstcorrosiveness. Fluctuatinggroundwater level and frequentflooding deteriorate thefoundation materials

With regard to its very slightrelief the zone is convenient.Difficulties occur in districtsof marshes and oxbow lakes

Abundant stocks ofhigh quality gravel andsand for the produc¬tion of concrete.Abundant fill material

Cuttings are excavatedmostly in moderateslopes. Eventualgroundwater influxesfrom the slope are easilycollected and drainedfrom the site

The construction of biggerfills may lead to slope fail¬ure. Use of a combination ofhalf fill-half cut of smallerdimensions would beadvantageous

This zone is less suitable forheavy construction of largersettlements and industrial struc¬tures. It is mainly suitable forsimpler structures

On account of clayey mate¬rials and the presence of deepscours, the zone is only condi¬tionally suitable for transportconstructions

Possible advan¬tageous large gravelpits and clay pits.Gravels of Pliocenecomplex are, however,of lesser quality

37


ENGINEERING-GEOLOGICAL CONDITIONS FOR CONSTRUCTION WORKS

Excavations andcuttings

Fill construction Structural foundations Roads Buildingmaterials

Cuttings and side-slopecuts will mainly beexcavated in slopewashdeposits and the under¬lying weathered rocks;ground water issuingfrom the slope is easilycollected and drainedfrom the site

The construction of largerfills may lead to slope fail¬ure. Use of a combination ofhalf fill-half cut would beadvantageous

Foundation conditions are verygood. The only serious problemis the question of ensuringslope stability during construc¬tion

When determining the line ofroads and railways difficultiesarise because of the effect ofthe gullies, and the needfor good drainage to maintainstability

Brick clays

As a rule foundationexcavations have to bemade below ground¬water level. In deeperexcavations in gravelslarge influxes of water

Does not cause difficulties,but strongly compressiblenon-load-bearing sludgyand putrified muddy accu¬

mulations in oxbow lakesand the fringes of alluvialcones require attention

In foundation of buildings withcellars difficulties are caused bythe high water table. Necessityof installing waterproofing(uplift pressure), in some cases

precautions againstcorrosiveness. Fluctuatinggroundwater level and frequentflooding deteriorate thefoundation materials

With regard to its very slightrelief the zone is convenient.Difficulties occur in districtsof marshes and oxbow lakes

Abundant stocks ofhigh quality gravel andsand for the produc¬tion of concrete.Abundant fill material

Cuttings are excavatedmostly in moderateslopes. Eventualgroundwater influxesfrom the slope are easilycollected and drainedfrom the site

The construction of biggerfills may lead to slope fail¬ure. Use of a combination ofhalf fill-half cut of smallerdimensions would beadvantageous

This zone is less suitable forheavy construction of largersettlements and industrial struc¬tures. It is mainly suitable forsimpler structures

On account of clayey mate¬rials and the presence of deepscours, the zone is only condi¬tionally suitable for transportconstructions

Possible advan¬tageous large gravelpits and clay pits.Gravels of Pliocenecomplex are, however,of lesser quality

37


5.2.2.2 Multipurpose, comprehensive, medium-scale map

Map ofengineering geological conditions in part of the ZvolenBasin (Czechoslovakia) at a scale of 1 : 25,000 (Matula, 1969).

Legend

. J - Hydroisobaths of the max. groundwater table

O ¿ Springs of fresh and mineral water

-ZZ~I- Waterlogged territory

~ ~ ~ Corrosiveness of groundwater: pH degree, hardnesspH^-T>i CO; of water (m German degrees); the full sector

\jf indicates the aggressivity of CO2, and/or SO4SO, according to Czechoslovak standards

Gully erosion

Formation of alluvial cones

Active landsUdes

Older (potential) landslides

Edges of river terraces

Boundary of Hthological complexes on the surface

J_ Boundary of complexes under the surface between :

(a) Quaternary deposits and (b) Quaternary depositsb and pre-Quatemary basement; between pre-Quater-

naiy complexes

V 10 Strike and dip of strata

1. --- Important tectonic faults and their dip

38


CommentsThis map was set up for the purposes of land-use planningand designing common structures and engineering works. Itcomprises two parallel sheets, the map of engineering geolog¬ical conditions (5.2.2.2) and the map of engineering geologi¬cal zoning (5.2.2.3).

In the map of engineering geological conditions rocksand soils are divided into lithological complexes, which aredistinguished by similar physical and engineering characteris¬tics. Rocks and soils occurring at the surface are presented ina colour pertinent to a respective lithogenetical complex andin an orange pattern which indicates hthological character.

Three-dimensional representation using the stripe-method is applied to show the character of two superim-

fx)sed lithological units of Quaternary deposits. The thick¬ness of these deposits < 2 m, 2-5 m and > 10 m is shown inthree shades of the particular colour. The hthological charac¬ter of the pre-Quatemary bedrock units, where overlain bysuperficial deposits, is shown in grey patterns. Thick patternsindicate the bedrock surface to 5 m in depth, lighter patternsare used for 5-10 m depth.

Hydrogeological conditions are represented in bluecolour by hydroisobaths of a maximum seaso,nal ground¬water level, in intervals of 2, 5 and 10 metres. Specific symbolsindicate the corrosiveness of the groundwater.

Distribution, kind and intensity of geodynamicprocesses, landslides, gully erosion, forming of alluvialcones, are shown in red.

GENETlC-LITHOLOGICAL CLASSIFICATION

Age Geneticgroup

Symbol Labelling of rocks Lithological complex

On thesurfacethickness (m)<2 2-5 5-10

Undersurfacecomplexes

Quaternary Fluvial }Q3 Sandy-loessic to loessic-clayey alluvial loams

?Q3-4 Alluvial sands predominantly medium-grained with loamyintercalations

?Q3-4 Fine- to medium-grained sandy gravels, loamy in olderterraces

.Q3-4 Sapropelic muds in abandoned river channels, sandy-loessic to clayey

Slopewash(Deluvial)

ÍQ3-4 DC Sandy-loessic to clayey slope loams

Chemical "N.-Q* Travertines, mounds and slope sheets

Pliocene Lacustrine I'fNj Lacustrine and alluvial clayey-loessic, sandy-loessic, rarelyclayey loams

Lacustrinefluvial

frN2 Lacustrine and alluvial sandy to loamy gravels with sand

beds

Miocene Volcaniclacustrine

'"Ni V V V ". V Stratified andesitic tuffs and tuffites

(contumed overleaf)

39


5.2.2.2 continued

II ENGINEERING CLASSIFICATIONS ' III ENGINEERING-GEOLOGICAL CHARACTER ISTIC

Symbol Building Road construction Soil Ease of For rock ni.ilcnal of the principal lithological types (on undisturbed samples)foundation classification excavation

.conditions Foundation Material for Lithological typesembankments

D2 ML 1-3 Sandy-loessic loams (in the Hron flood-plain)[Q3_4 MV MV

D3 CL 1-3 Clayey-loessic loams (in older terraces)

,Q3-4 C2 V VV SM 2 Loamy sands

?Q3-4 Bt VV VV 4 Sandy gravels (Hron valley terraces)

GM

0Q3-4 E3 N N OH 2-3 Sapropelic muddy silts of abandoned river arms in thefloodplain 5

JQ3-4 Ul MV MV CL 2-3 Sandy-loessic loam

D3

rN _q A N My 5 More compact travertine

Strongly porous travertine

i'fN2

ffN2

D2

D3

Bt

MV

VV

MV

V

CL

ML

GV

GM

2-3 Loessic-clayey soil

Sandy-loessic soil

Weathered sandy gravels

Loamy gravels

uN » v MV S-fi Andesitic psammitic tuffsPsammitic tuffites

Psephitic tuffites

40


5.2.2.2 continued

II ENGINEERING CLASSIFICATIONS ' III ENGINEERING-GEOLOGICAL CHARACTER ISTIC

Symbol Building Road construction Soil Ease of For rock ni.ilcnal of the principal lithological types (on undisturbed samples)foundation classification excavation

.conditions Foundation Material for Lithological typesembankments

D2 ML 1-3 Sandy-loessic loams (in the Hron flood-plain)[Q3_4 MV MV

D3 CL 1-3 Clayey-loessic loams (in older terraces)

,Q3-4 C2 V VV SM 2 Loamy sands

?Q3-4 Bt VV VV 4 Sandy gravels (Hron valley terraces)

GM

0Q3-4 E3 N N OH 2-3 Sapropelic muddy silts of abandoned river arms in thefloodplain 5

JQ3-4 Ul MV MV CL 2-3 Sandy-loessic loam

D3

rN _q A N My 5 More compact travertine

Strongly porous travertine

i'fN2

ffN2

D2

D3

Bt

MV

VV

MV

V

CL

ML

GV

GM

2-3 Loessic-clayey soil

Sandy-loessic soil

Weathered sandy gravels

Loamy gravels

uN » v MV S-fi Andesitic psammitic tuffsPsammitic tuffites

Psephitic tuffites

40


Specificgravityps[gcm-3]

2.692

2.61

2.65

2.65-2.68

Dry bulkdensitypd[gcm"3]

1 51

1.42-1.62'1.57

1.30-1.78

1.30-1.704

1.80-1.90

Porosity

%

4339-47

36-51

36-47

Consistency Ic

Rebound hardness(R Schmidt)

060.1-0.9

0.80.4-1.3

Moisturecontent%

3025-32

2915-35

9-10

w%

2421-30

2918-35

W| %

32-1441

30-54

ip%

Indentationhardness[kgf mm-2]

1410-22

16

7-24

2.60 1.37 48 0.13 33 21 35 14

2.67

2.66

2.68

2 63

1.62

1.13-1.77

1.93

1.60

1761.15-1.60

1 671.30-1.70

40

32-58

8

16

4540-55

3730-50

0.7

0.5-1.3

0.3-1.009

0.7-1.1

26

18^13

2923^6

2014-39

23

17-40

2519-40

2015-24

39

23-52

4029-60

3622^18

14

6-20

150

16

12-2315

6-24

2.68

2.71

2.61

1.68

1.69

1.85

36

37

29

16

26

48

70

ft onimued o\ ci leafJ

41


Specificgravityps[gcm-3]

2.692

2.61

2.65

2.65-2.68

Dry bulkdensitypd[gcm"3]

1 51

1.42-1.62'1.57

1.30-1.78

1.30-1.704

1.80-1.90

Porosity

%

4339-47

36-51

36-47

Consistency Ic

Rebound hardness(R Schmidt)

060.1-0.9

0.80.4-1.3

Moisturecontent%

3025-32

2915-35

9-10

w%

2421-30

2918-35

W| %

32-1441

30-54

ip%

Indentationhardness[kgf mm-2]

1410-22

16

7-24

2.60 1.37 48 0.13 33 21 35 14

2.67

2.66

2.68

2 63

1.62

1.13-1.77

1.93

1.60

1761.15-1.60

1 671.30-1.70

40

32-58

8

16

4540-55

3730-50

0.7

0.5-1.3

0.3-1.009

0.7-1.1

26

18^13

2923^6

2014-39

23

17-40

2519-40

2015-24

39

23-52

4029-60

3622^18

14

6-20

150

16

12-2315

6-24

2.68

2.71

2.61

1.68

1.69

1.85

36

37

29

16

26

48

70

ft onimued o\ ci leafJ

41


5.2.2.2 continued

III. ENGINEERING-GEOLOGICAL CHARACTERISTIC (cOtlt.)

For rock material of the principal lithological types (on undisturbed samples) (coni.)

Symbol Shearingstrength<p in degrees

Cohesionc m

kgf.cm~2

Uniaxialcompressivestrengthaf[kgfcm"J]

Modulus of compressibility [kgf.cm 2]

Modulus ofelasticity E(10 -*kp.cm-a)

Modulus ofdeformation E

Modulus of dynamicelasticity Edya

ÍQ3-425

11

0.5

0.8

85

?Q3 27 0.1

?Q3-4 30 36

0Q3

¿Q3-4 21 0.8 102-140

'N2-Q4302

118

84 kz=0.87<¡

kz = 0.60

i'rN29

14

1.0

0.7

80

147-105

frN2

UN,115-171 4 2.8 5 kz = 0.61-0.71225 10.9 4.3 15 kz = 0.78115 kz = 0.38

1. Classification according to CSN (Czechoslovak Building Standard): A2 = soft rocks, Bi = gravels with pebbles in contact, C2 = medium to fine sands, D2 = clays of medium plasticity,D¡= clays of high plasticity, E3=orgamc silky clays, VV = very suitable, V= suitable, MV = barely suitable, N = unsuitable.

2. Mean statistical values.3. Medium and minimum-maximum values.4. Minimum-maximum values5. Analogous values from neighbouring area.6. kz coefficient of softening (ratio of saturated to dry strength).

42


5.2.2.2 continued

III. ENGINEERING-GEOLOGICAL CHARACTERISTIC (cOtlt.)

For rock material of the principal lithological types (on undisturbed samples) (coni.)

Symbol Shearingstrength<p in degrees

Cohesionc m

kgf.cm~2

Uniaxialcompressivestrengthaf[kgfcm"J]

Modulus of compressibility [kgf.cm 2]

Modulus ofelasticity E(10 -*kp.cm-a)

Modulus ofdeformation E

Modulus of dynamicelasticity Edya

ÍQ3-425

11

0.5

0.8

85

?Q3 27 0.1

?Q3-4 30 36

0Q3

¿Q3-4 21 0.8 102-140

'N2-Q4302

118

84 kz=0.87<¡

kz = 0.60

i'rN29

14

1.0

0.7

80

147-105

frN2

UN,115-171 4 2.8 5 kz = 0.61-0.71225 10.9 4.3 15 kz = 0.78115 kz = 0.38

1. Classification according to CSN (Czechoslovak Building Standard): A2 = soft rocks, Bi = gravels with pebbles in contact, C2 = medium to fine sands, D2 = clays of medium plasticity,D¡= clays of high plasticity, E3=orgamc silky clays, VV = very suitable, V= suitable, MV = barely suitable, N = unsuitable.

2. Mean statistical values.3. Medium and minimum-maximum values.4. Minimum-maximum values5. Analogous values from neighbouring area.6. kz coefficient of softening (ratio of saturated to dry strength).

42


For rock complexes (in situ)

Thickness 0-2 m. Horizontal thin to laminar bedding. Vertical anisotropy. Strong slaking. Soft to solid consistency. Intercalations of organic soils.Slight permeability.

Thickness 0-1.5 m. Medium sands, intercalations of silts, cross-bedded. Considerable loam admixture decreases the permeability and increasescoherence. Facially very variable. Strongly weathered in older terraces.

Sandy medium gravels with sand intercalations 3-9 m thick. Irregular bedding, vertical anisotropy. Moderate permeability 5.10-4 m/s. Water-bearing,locally corrosive. Boulders at the base. In older terraces strongly weathered, loamy, permeability 3.10-6. In lateral valleys coarse, bouldery,heterogeneous.

Deposits occupy numerous irregular abandoned river arms and depressions at the edges of alluvial cones. Sandy and loessic sapropelic muds,very soft to soft consistency, water saturated. Very low permeability, slakes readily. No bearing capacity, very strongly compressible.

Irregularly to cryptobedded, predominantly 1.5-3 m thick, at the foot of slopes more than 10 m thick, sandy-loessic brown loams, with fragmentsof volcanic rocks. On Pliocene deposits more clayey, rust-brown, with gravels. Stiff to very stiff, weather to prismatic fragments. In places slakereadily. Very slightly permeable. Used for brick making.

Irregular bodies, accumulations and sheets adapted to the relief. Variable thickness. Semi-solid rocks, strongly fissured, macroporous and permeable.Soluble, karstified. Hardly suitable for building or decorative stone.

Facially very homogeneous cryptobedded clayey to sandy-loessic soils, up to 10-15 m thick. Brown to rusty-brown, spotted. Stiff to very stiffconsistency. Diagenetically consolidated. Prismatic disintegration. Practically impermeable.

Sandy-loamy medium gravels 5-50 m thick. Lenticular intercalations of sands. Strongly weathered, in places weakly cemented. Medium permeability.

Coarse-bedded psephitic-psammitic tuffs deposited in water environment. They alternate with psephitic to pelitic tuffites. Varied colours, facialvariability and physical heterogeneity. Weak semi-solid rocks, weather readily, disintegrate in water. Little jointing and low permeability.

43


For rock complexes (in situ)

Thickness 0-2 m. Horizontal thin to laminar bedding. Vertical anisotropy. Strong slaking. Soft to solid consistency. Intercalations of organic soils.Slight permeability.

Thickness 0-1.5 m. Medium sands, intercalations of silts, cross-bedded. Considerable loam admixture decreases the permeability and increasescoherence. Facially very variable. Strongly weathered in older terraces.

Sandy medium gravels with sand intercalations 3-9 m thick. Irregular bedding, vertical anisotropy. Moderate permeability 5.10-4 m/s. Water-bearing,locally corrosive. Boulders at the base. In older terraces strongly weathered, loamy, permeability 3.10-6. In lateral valleys coarse, bouldery,heterogeneous.

Deposits occupy numerous irregular abandoned river arms and depressions at the edges of alluvial cones. Sandy and loessic sapropelic muds,very soft to soft consistency, water saturated. Very low permeability, slakes readily. No bearing capacity, very strongly compressible.

Irregularly to cryptobedded, predominantly 1.5-3 m thick, at the foot of slopes more than 10 m thick, sandy-loessic brown loams, with fragmentsof volcanic rocks. On Pliocene deposits more clayey, rust-brown, with gravels. Stiff to very stiff, weather to prismatic fragments. In places slakereadily. Very slightly permeable. Used for brick making.

Irregular bodies, accumulations and sheets adapted to the relief. Variable thickness. Semi-solid rocks, strongly fissured, macroporous and permeable.Soluble, karstified. Hardly suitable for building or decorative stone.

Facially very homogeneous cryptobedded clayey to sandy-loessic soils, up to 10-15 m thick. Brown to rusty-brown, spotted. Stiff to very stiffconsistency. Diagenetically consolidated. Prismatic disintegration. Practically impermeable.

Sandy-loamy medium gravels 5-50 m thick. Lenticular intercalations of sands. Strongly weathered, in places weakly cemented. Medium permeability.

Coarse-bedded psephitic-psammitic tuffs deposited in water environment. They alternate with psephitic to pelitic tuffites. Varied colours, facialvariability and physical heterogeneity. Weak semi-solid rocks, weather readily, disintegrate in water. Little jointing and low permeability.

43


5.2.2.3 Multipurpose comprehensive, medium-scale map

Map of engineering geological zoning, Zvolen Basin 1 : 25,000

Legend

, -S ^^ Hydroisobaths of the max. groundwater table

Q Springs of fresh and mineral water

-"-"2_^- Waterlogged territory

Districts affected by intensive gully erosion

Boundaries of zones

Boundaries of subzones

Fu , Dtn Symbols for zones

h 2g! Symbols for subzones

pH^^-pv COj Corrosiveness of groundwater : pH degree, hardnessf of water (in German degrees); the full sector indi¬

te SO, cates the aggressivity of CO2 and/or SO4

. ^ Spa-protection zones

:\^ W; District affected by landsliding

3

b

b JMHii1

t

Pre-Quatemary soils with the surface in the depth(a) <5m,(b)5-10m

Pre-Quatemary semisolid rocks with the surface inthe depth, (a) <5 m, (b) 5-10 m

44


Comments

While the previous map presents information on the distri¬bution and character of individual principal components ofthe engineering geological environment (rocks and soils,groundwater, geodynamical process), a comprehensive evalu¬ation of these interrelated components at different placeswithin the map area is presented in the map of engineeringgeological zoning.

The method of typological zoning is apphed to delimitdifferent types of map zones and subzones. The discrimina¬tion of engineering geological zones is based on the unifor¬mity in general lithological character and structural arrange¬ment of lithological complexes in the uppermost parts of theground. Engineering geological subzones are delimited with

in the zones on the basis of homogeneity in spatial (super¬position) and proportional (thickness) arrangement of indivi¬dual types of soils and rocks in schematized type cross-sections of the foundation soils.

Individual zones are indicated by symbols, expressingthe genetical-lithological character of rocks (for example,Fu = zone of river valley deposits, Ft = zone of deposits inriver terraces. Dm = zone of slope-wash deposits on magmaticor metamorphic rocks, Ep = zone of aeolian sands, etc.;there are forty types of zones adopted in the zoning classifi¬cation in C.S.S.R.). Should it be deemed necessary to takeinto consideration two superimposed complexes of smallerthickness, it is possible to indicate such zones also by com¬bined symbols (for example, EsFt=zone of river terrace de¬

posits overlain by aeolian loess).

SUBZONES

Type Geotogical-geomorphologicalcharacteristic

Hydrogeological conditions Geodynamicconditions

Type Pattern(on the map)

Lithological characteristicVertical hthologicalcomposition

Ng PUocene gravels alternatingwith sand horizons forming a

flat rolling landscape withmoderate slopes. Slopewashloams and sands with somegravel < 1 m thick

Groundwater usuallymore than 5 m deep.Small springs fromgravelly horizons

Extensive gullyerosion. Slides ofsmall extent

G3

<1

>5 Ng

Gravels, sandygravels, less loamygravels, with sand andclayey-sandy horizons

Dm Slopewash loams 5-8 m thickon andesitic agglomerates andtuffs. Moderate slopes, locallyintensively dissected byerosion

Very slightly water¬bearing slopewash onrelatively permeablebedrock

Extensive sheet

and gully erosion.Shallow landslidesand earth flows

h2B'

DMh2

Slopewash loams,clayey, less sandy, stiffto very stiff, 2-5 mthick, on agglomeratictuffs and agglomer¬ates, interbedded withlapiHi tuffs

Fu Floodplain alluvium formedof gravel beds 5-9 m thickcovered by sand, or loam0.5-2 m thick

Territory regularlyaffected by large floods.Water table usually<2 m deep. Waterlocally corrosive (highSO4 content)

In places the riverbanks areundercut

klg3B' Loam and sand0.5-2 m thick, under¬lain with sandygravels 6-9 m thick. Inthe depth of 5-9 msubstratum as in zoneDm (tuffs)

Note In this table the characteristics for only three selected types of subzones of three typical zones are presented as an example.

45


Subzones are quasihomogeneous models of qualitativeand quantitative vertical structure of zonation grounds andtheir delimitation is made according to the following criteria(abbreviated) :

Quaternary deposits

g = Gravelly soilsp = Sandy soilsn= Alternation of gravelly

and sandy soilsh = Cohesive soilsk=Combination of cohesive

and uncohesive soilss = Loess soilso = Organic soilsb = Bouldery soils

Pre-Quaternary basement

S = Solid (hard) rocksB = Semisolid (weak) rocksF = Alternation of hard and

weak rocks (flyschoid)Z= Highly weathered rocksG = Gravelly soilsP= Sandy soilsN = Alternation of gravels

and sandsI = Cohesive soils

K = Combination of cohesiveand non-cohesive soils

Strata thickness

1= <2m2 = 2-5 m3=>5m

Depth of pre-Quaternary sur¬

face

l = <5m2=5-10m3=>10m

Subzones are indicated by symbols, which are formed bygrouping the corresponding signs for soil and rock (type,thickness, or depth of the pre-Quaternary basement) accord¬ing to vertical sequence of delimited strata. For example thesymbol hlg2S' expresses the model of the foundation soil, inwhich cohesive soils (thickness <2 m) are underlain bygravels (thickness 2-5 m) and in the depth to <5 m hardrocks of pre-Quaternary basement occur.

Estimated bearing capacityq kgf/ cm "2 at a 2m,6 m depthfor foundation width 1 mDepth of water belowfoundation

>1 m

7

~9~

<1 m

4.7

"6"

Pile bearingcapacityPiles 01,000 cm2,length 6 m

(Mp)

60

Foundation evaluation accordingto the standard for foundation

Foundation conditionssimple. Foundation sitesuitable. Only condi¬tionally suitable in loamygravels. Gravels andsandy gravels, class 8 and10. Loamy gravels, class 9and 11

ENGINEERING-GEOLOGICAL

Suitability for road founda¬tion according to standard fortransport roads

Road onnaturalsubgrade

Verysuitable

Embankmenton naturalsubgrade

Verysuitable

AND GEOTECHN1CAL CHARACTERISTICS OF THE SUBZONES

Capillarity

None(medium)

Frostsusceptibility

None(medium)

Evaluation of roadconstructionconditions

Territorysuitable forroads incuttings andembankments

1.2

~6~12 60

40

Foundation conditionssimple. Loams, class 20and 21. Substratum class,

2 to 5. Foundation sitesconditionally suitable

Foundation conditionssimple. Foundation sitesmay be unsuitablebecause of high water orflooding

Barelysuitable

Stratum I(loam-sand)littlesuitable.Stratum II(gravel)very

suitable

Barelysuitable

Stratum I(loamsand)littlesuitable.Stratum II(gravel)very

suitable

High

Mediumto high

High

Mediumto high

Because of soilcharacter andextensivedissection,territorybarely suitablefor transportroad

Because ofhydro-geologicalconditionsroads shouldbe built onembankments

46


Subzones are quasihomogeneous models of qualitativeand quantitative vertical structure of zonation grounds andtheir delimitation is made according to the following criteria(abbreviated) :

Quaternary deposits

g = Gravelly soilsp = Sandy soilsn= Alternation of gravelly

and sandy soilsh = Cohesive soilsk=Combination of cohesive

and uncohesive soilss = Loess soilso = Organic soilsb = Bouldery soils

Pre-Quaternary basement

S = Solid (hard) rocksB = Semisolid (weak) rocksF = Alternation of hard and

weak rocks (flyschoid)Z= Highly weathered rocksG = Gravelly soilsP= Sandy soilsN = Alternation of gravels

and sandsI = Cohesive soils

K = Combination of cohesiveand non-cohesive soils

Strata thickness

1= <2m2 = 2-5 m3=>5m

Depth of pre-Quaternary sur¬

face

l = <5m2=5-10m3=>10m

Subzones are indicated by symbols, which are formed bygrouping the corresponding signs for soil and rock (type,thickness, or depth of the pre-Quaternary basement) accord¬ing to vertical sequence of delimited strata. For example thesymbol hlg2S' expresses the model of the foundation soil, inwhich cohesive soils (thickness <2 m) are underlain bygravels (thickness 2-5 m) and in the depth to <5 m hardrocks of pre-Quaternary basement occur.

Estimated bearing capacityq kgf/ cm "2 at a 2m,6 m depthfor foundation width 1 mDepth of water belowfoundation

>1 m

7

~9~

<1 m

4.7

"6"

Pile bearingcapacityPiles 01,000 cm2,length 6 m

(Mp)

60

Foundation evaluation accordingto the standard for foundation

Foundation conditionssimple. Foundation sitesuitable. Only condi¬tionally suitable in loamygravels. Gravels andsandy gravels, class 8 and10. Loamy gravels, class 9and 11

ENGINEERING-GEOLOGICAL

Suitability for road founda¬tion according to standard fortransport roads

Road onnaturalsubgrade

Verysuitable

Embankmenton naturalsubgrade

Verysuitable

AND GEOTECHN1CAL CHARACTERISTICS OF THE SUBZONES

Capillarity

None(medium)

Frostsusceptibility

None(medium)

Evaluation of roadconstructionconditions

Territorysuitable forroads incuttings andembankments

1.2

~6~12 60

40

Foundation conditionssimple. Loams, class 20and 21. Substratum class,

2 to 5. Foundation sitesconditionally suitable

Foundation conditionssimple. Foundation sitesmay be unsuitablebecause of high water orflooding

Barelysuitable

Stratum I(loam-sand)littlesuitable.Stratum II(gravel)very

suitable

Barelysuitable

Stratum I(loamsand)littlesuitable.Stratum II(gravel)very

suitable

High

Mediumto high

High

Mediumto high

Because of soilcharacter andextensivedissection,territorybarely suitablefor transportroad

Because ofhydro-geologicalconditionsroads shouldbe built onembankments

46


For the abbreviation of symbols (mainly in small sub-zones) on the map the signs of the pre-Quatemary basementare left out from the symbols. Instead the character anddepth of the basement on the map is shown by grey patternsin different weight.

Apart from the division of the map territory into zoningunits with approximately similar engineering geological con¬

ditions, the information for the user is completed by present¬ing also data on hydrogeological conditions. The parts of theterritory affected by certain geodynamic processes are delim¬ited as particular districts. Indicated also are various protec¬ted areas.

Maximum slope angle intemporary excavations.

r, L3mDepth4m

Estimated maximum flow in 1 /mm through Ease of1 m of the circumference of the excavation excavationto lower the water table by

Possible rock use Recommendations for additional investigations

Dry

1:1.41:1.8

1:2.2

1:2.5

15 50 2-3 Gravel and loamextraction ; gravels of poorquality

Because of the irregular occurrence ofsand and clayey-sand intercalations adense network of boreholes is required

1:0.71:0.9

1:1.3

1:1.2

<1 <1 2-3 Very variable pétrographie compositionand consistency of loams

1:1.4 1:2.2 40 180 400 1-2 Considerable quantities of1:1.8 1:2.5 2-3 a good quality fluvial

gravel for concrete

Variable corrosive ground waterproperties

47


For the abbreviation of symbols (mainly in small sub-zones) on the map the signs of the pre-Quatemary basementare left out from the symbols. Instead the character anddepth of the basement on the map is shown by grey patternsin different weight.

Apart from the division of the map territory into zoningunits with approximately similar engineering geological con¬

ditions, the information for the user is completed by present¬ing also data on hydrogeological conditions. The parts of theterritory affected by certain geodynamic processes are delim¬ited as particular districts. Indicated also are various protec¬ted areas.

Maximum slope angle intemporary excavations.

r, L3mDepth4m

Estimated maximum flow in 1 /mm through Ease of1 m of the circumference of the excavation excavationto lower the water table by

Possible rock use Recommendations for additional investigations

Dry

1:1.41:1.8

1:2.2

1:2.5

15 50 2-3 Gravel and loamextraction ; gravels of poorquality

Because of the irregular occurrence ofsand and clayey-sand intercalations adense network of boreholes is required

1:0.71:0.9

1:1.3

1:1.2

<1 <1 2-3 Very variable pétrographie compositionand consistency of loams

1:1.4 1:2.2 40 180 400 1-2 Considerable quantities of1:1.8 1:2.5 2-3 a good quality fluvial

gravel for concrete

Variable corrosive ground waterproperties

47


5.3 Examples of special purpose engineering geological maps

5.3.1 SPECIAL PURPOSE ANALYTICAL MAPS

5.3.1.1 Special purpose, analytical, small-scale map

Map of relative ease of excavation,Utah (United States), at ascale of approximately 1 : 2(X),000

Legend

3

Excavation very easy

Excavation easy

Excavation easy to difficult; variability due to inter-bedded resistant and soft rocks

Excavation difficult

Excavation very difficult

48


This map shows relative ease (or difficulty) with which rocksand surficial deposits can be excavated. Because of rapidlychanging technology of excavation and considerable localvariability of many rock units, it is not practical to specifical¬ly categorize rock units according to type of equipmentneeded for their excavation. However, it may be stated ingeneral that rock units classed as very easy and easy can inmost places be excavated by hand tools and by light machin¬ery such as backhoes and small bulldozers ; units included ineasy to difficult require blasting and (or) heavy machinerysuch as rippers and large bulldozers for resistant rocks, andhand tools or light power equipment for soft rocks, and unitsclassed as difficult and very difficult probably require blastingand heavy machinery.

The excavation units shown here are based on map unitsof the geologic map of the Salina quadrangle. Wherebedrock is mantled with thin unmapped surficial deposits,ease of excavation shown is that of the bedrock, not that ofthe thin surficial mantle; where surficial deposits aremapped, ease of excavation shown is that of the surficialdeposits.

Comment

The map selected here as an example of a special purpose,analytical, small-scale map is one of a series of maps preparedfor the same area at a scale of 1 : 250,000. Map 1-591 (sheet 1

of two) is a standard type of geological map with an exten¬sive descriptive legend of surficial and solid formations. Itserves to emphasize the close relationship between structureand stratigraphy and the derived 'ease-of-excavation' mapillustrated here.

Other complementary maps in the series provide an ex¬

ample of the use of structural contours (map 1-591, sheet 2of two). Hydrological and hydrogeological maps includemap 1-59 1-D, showing normal annual and monthly precipi¬tation in the Salina Quadrangle, Utah; map I-591-F, surfacewater, map 1-59 1-G, springs; map 1-59 1-K, general chemi¬cal quality of groundwater; map I-591-M, general avail¬ability of groundwater; and map 1-59 1-N, drainage basinsand historic cloudburst floods. Other specialized maps in¬

clude map I-591-E showing the length of freeze-free season,and map 1-59 1-H which shows the distribution of differenttypes of bedrock and surficial deposits. The latter is a litho¬logical map showing twenty-one lithological groupings withshort descriptions, in the place of the eighty-three formationsand other lithostratigraphical types depicted on the geologi¬cal map. Basically map H is a simplified version of the maingeological map, and illustrates the difference between litho¬logical maps and lithostratigraphical maps.

This example has been redrawn from a part ofP. L. Williams, Map Showing Relative Ease of Excavation inthe Salina Quadrangle , Utah. Folio of the Salina Quadrangle,Utah Map I-591-J. United States Geological Survey, 1972.

49


This map shows relative ease (or difficulty) with which rocksand surficial deposits can be excavated. Because of rapidlychanging technology of excavation and considerable localvariability of many rock units, it is not practical to specifical¬ly categorize rock units according to type of equipmentneeded for their excavation. However, it may be stated ingeneral that rock units classed as very easy and easy can inmost places be excavated by hand tools and by light machin¬ery such as backhoes and small bulldozers ; units included ineasy to difficult require blasting and (or) heavy machinerysuch as rippers and large bulldozers for resistant rocks, andhand tools or light power equipment for soft rocks, and unitsclassed as difficult and very difficult probably require blastingand heavy machinery.

The excavation units shown here are based on map unitsof the geologic map of the Salina quadrangle. Wherebedrock is mantled with thin unmapped surficial deposits,ease of excavation shown is that of the bedrock, not that ofthe thin surficial mantle; where surficial deposits aremapped, ease of excavation shown is that of the surficialdeposits.

Comment

The map selected here as an example of a special purpose,analytical, small-scale map is one of a series of maps preparedfor the same area at a scale of 1 : 250,000. Map 1-591 (sheet 1

of two) is a standard type of geological map with an exten¬sive descriptive legend of surficial and solid formations. Itserves to emphasize the close relationship between structureand stratigraphy and the derived 'ease-of-excavation' mapillustrated here.

Other complementary maps in the series provide an ex¬

ample of the use of structural contours (map 1-591, sheet 2of two). Hydrological and hydrogeological maps includemap 1-59 1-D, showing normal annual and monthly precipi¬tation in the Salina Quadrangle, Utah; map I-591-F, surfacewater, map 1-59 1-G, springs; map 1-59 1-K, general chemi¬cal quality of groundwater; map I-591-M, general avail¬ability of groundwater; and map 1-59 1-N, drainage basinsand historic cloudburst floods. Other specialized maps in¬

clude map I-591-E showing the length of freeze-free season,and map 1-59 1-H which shows the distribution of differenttypes of bedrock and surficial deposits. The latter is a litho¬logical map showing twenty-one lithological groupings withshort descriptions, in the place of the eighty-three formationsand other lithostratigraphical types depicted on the geologi¬cal map. Basically map H is a simplified version of the maingeological map, and illustrates the difference between litho¬logical maps and lithostratigraphical maps.

This example has been redrawn from a part ofP. L. Williams, Map Showing Relative Ease of Excavation inthe Salina Quadrangle , Utah. Folio of the Salina Quadrangle,Utah Map I-591-J. United States Geological Survey, 1972.

49


5. 3. 1 .2 Specialpurpose, analytical, medium-scale map

Map of foundation suitability of soils near Marseille (France)reproduced at a scale of 1 : 35,500

Comment

The complete map, covering an area of approximately1,000 km2, indicates the suitabihty as foundation material(bearing capacity) of the soil in general terms for depths of0-3 m, 3-6 m and 6-9 m. The soils in the three layers havebeen classified as good or very good (GVG) in green, goodon the whole (G) in yellow, bad and locally mediocre (B)in red, and very bad and fill material (VB) in violet.

No documentation details are given, and it is not knownwhether the mapping has been based on physical andmechanical tests or on lithological description of the rocks.On the complete map sheet the isopiestic lines for the water-table of La Crau are given; these are the only hydro-geological data given (Sanejouand, 1972, p. 32).

50


Recognition of four qualities of soil and three distinctlayers makes it theoretically possible to show sixty-fourdifferent zones on the map. Although the system is veryflexible, it is doubtful whether it is realistic to give regionalestimates for layers of constant thickness, and whether thesmall scale of the map justifies recognition of three depthzones. In addition, the printed map is not particularly legible.However, the cartographic solution to the problem is notwithout interest as a method of possible general applicationin appropriate situations.

The map is part of the 1 : 50,000 map of the Bassin de

la Crau et de l'Etang de Berre, Carte d'Aptitude des Sols auxFondations prepared in 1969 by the Laboratoire Régionaldes Ponts et Chaussées de Marseille for the OrganisationRégionale d'Etude d'Aire Métropolitaine 13.

Legend

Good or verygood. GVGfrom 0 to 9 m

G to 3 m.B3-9m

r

A

G to 6 m.GVG 6-9 m

Good on thewhole. G fromOto 9 m

G to 3 m.VB 3-9 m

J

G to 6 m.B6-9m

I Bad, locallymediocre.B from 0 to 9 m

GVG to 3 m.G 3-9 m

J

G to 6 m.VB 6-9 m

Very bad andfill. VBfrom 0 to 9 m

GVG to 3 m.B3-9m 2ZZZ °

GVG to 6 m.16-9 m

VB to 3 m.GVG 3-9 m

GVG to 3 m.VB 3-9 m "777?

GVG to 6 m.B6-9m

VB to 3 m.G 3-9 m

VB to 6 m.GVG 6-9 m

W / / Ä GVG to 6 m.mSmy vB6-9m

VB to 3 m.B3-9m

B to 3 m.GVG 3-9 m

B to 3 m.G 3-9 m

B to 3 m.B3-9m

G to 3 m.GVG 3-9 m

S^

VB to 6 m.G 6-9 m

. VB to 6 m./X /VA B6-9m

21

21

B to 6 m.GVG 6-9 m

B to 6 m.G 6-9 m

B to 6 m.VB 6-9 m

6.00 mto

9.00 m

GVG

51


5.3.2 SPECIAL PURPOSE COMPREHENSIVE MAPS

5.3.2.1 Specialpurpose, comprehensive, small-scale map

Map of part of the Northeast Corridor, Washington, D.C., to Boston (United States), reproduced at approximately 1:265,000;produced for transport planning

Legend

The map units are based on lithology and do notimply stratigraphie succession. See pages 52 and 53

for detailed descriptions and engineering properties.

n

c

Basalt flows, diabase dykes, and sills

Chiefly red sandstone and shale withconglomerate

Chiefly red shale

Greenstone

Fine-grained mica schist, chlorite schistand phyllite with interbedded sequencesof micaceous quartzite

Mica schist and mica gneiss, medium tocoarsely crystalline

Quartzite, with interbedded conglomer- ^^(li°<ate, schist and gneiss

Massive to gneissic granitic rocks.Range in composition from quartz dio-rite to granite

Layered gneissStrongly layered; layers differ sharply in composition. Mineralogydepends on degree of metamorphism. Includes interbedded amphi-bolite, hypersthene granulite, quartz-plagioclase gneiss, biotite-quartz-feldspar gneiss, mica schist, greenstone and schistose felsite.

Amphibolite, epidote amphibolite, andwell-foliated metagabbro

Contact

FaultDashed where approximately located

Legend

Till overlying bedrock. Younger ground moraine

Sand and gravel. Stratified glacial deposits and allu¬vium in valleys

Silt or clay within or beneath surficial deposits

Contact

52


Comment

The illustration is based on a small part of sheet 4 of fivemap sheets, prepared in 1967 by the United States Geologi¬cal Survey at the request of the United States Department ofTransportation of the Northeast Corridor, betweenWashington, D.C., and Boston, Massachusetts. Publishedmap scale is 1 : 250,000.

The upper map segment shows the bedrock geology; thelower map is of the coastal plain and surficial geology. Athree-part report (map 1-514) consists of a map oi mw

bedrock geology with geological cross-sections (map 1-5 14A,

sheets 1 to 5), a table of geological descriptions and engineer¬ing characteristics of each geological map unit (sheet 6), amap showing sources of data (sheet 7), and a list of addi¬tional references. Map I-514B contains information on thecoastal plain and surficial deposits, and map 1-5 14C containsdata on earthquake epicentres, geothermal gradients, andmajor excavations and borings that serve as sources of en¬

gineering data (documentation map) within the NortheastCor'' !or.

( è Typical entries in the tabular descriptions of geologicaland engineering characteristics of a bedrock map unit and asurficial deposit map unit are reproduced on pages 52 and 53.

53


Comment

The illustration is based on a small part of sheet 4 of fivemap sheets, prepared in 1967 by the United States Geologi¬cal Survey at the request of the United States Department ofTransportation of the Northeast Corridor, betweenWashington, D.C., and Boston, Massachusetts. Publishedmap scale is 1 : 250,000.

The upper map segment shows the bedrock geology; thelower map is of the coastal plain and surficial geology. Athree-part report (map 1-514) consists of a map oi mw

bedrock geology with geological cross-sections (map 1-5 14A,

sheets 1 to 5), a table of geological descriptions and engineer¬ing characteristics of each geological map unit (sheet 6), amap showing sources of data (sheet 7), and a list of addi¬tional references. Map I-514B contains information on thecoastal plain and surficial deposits, and map 1-5 14C containsdata on earthquake epicentres, geothermal gradients, andmajor excavations and borings that serve as sources of en¬

gineering data (documentation map) within the NortheastCor'' !or.

( è Typical entries in the tabular descriptions of geologicaland engineering characteristics of a bedrock map unit and asurficial deposit map unit are reproduced on pages 52 and 53.

53


BEDROCK MAP UNIT

Geological description

Map Unit. Amphibolite, epidote amphibolite, and metamorphosedgabbro.

Equivalent geological unit.1 Baltimore gneiss (part); Brimfield for¬mation (part); Glastonbury gneiss (part); Maltby lakes volcan-ics (part); Marlboro formation (part); Middletown formation(part); Putnam gneiss (part); Tatnic hill formation (part); un¬

named units.Lithology. Massive to banded, tough, strong amphibolite, amphi¬

bolite schist, amphibolite gneiss, hornblende gneiss; in partmetagabbroic. Forms extensive thick layers, lenses and pods.Commonly epidote-bearing; much epidote-rich amphibolitegneiss, and pods of epidote; includes extensive thick light-red topink garnet-rich, layers. In places schistose toward margins;locally intruded by quartz diorite dykes.

Structure. Structure variable; rock ranges from massive to gneiss-ic. Large massive bodies rarely show folds, whereas smaller orlayered bodies commonly are complexly folded. Joints common¬ly persistent, but vary greatly in spacing.

Weathering. Weathers to sticky red clay south-west of glaciatedarea ; almost unweathered in glaciated area.

Topography. Hills to low mountains; rugged in places, especiallynear rivers.

Physicalproperties 2

Dry unit weight (kg per cubic metre). 3,000-3,200.Compressive strength.3 High to very high.

Engineering characteristics

Evaluation of rock for construction.4

Young's modulus of elasticity.5 High to very high.Relative drillabilityfi 2.

Excavation characteristics. Overbreak reported moderate to exces¬

sive depending on orientation of excavation to major joint sys¬

tems. Rock loads mostly slight. Swelling ground probable in wetshear zones. Contains fibrous minerals which may slow excava¬

tion by boring machine.

Hydrologie conditions1

Significant hydrolic features. Water occurs in weathered zone atshallow depth, probably not much below 45 m. Maximumyields from fault zones.

Permeability. Secondary. Primary fracturing; chemical weathering.Depth of wells. Range: 10-230 m. Median: 47.5 m.Yield of wells. Range: 2.2-675 litres per minute. Median: 54 litres

per minute.

1 . The stratigraphie nomenclature used in this report is that of the authors of the variousdata sources and does not necessarily conform with usage of the United States Geo¬logical Survey.

2. Physical data available only for some rock units; where data are lacking, the physicalproperties are inferred from comparisons with those of rock elsewhere that possess

similar composition, structure and geological histories3 Classification is for uniaxial compressive strength of intact rock. Strength is reduced

by physical defects and chemical alteration in rock, it may differ with respect tobedding, foliation or direction of principal residual stress.

Strength class Range of compressivestrength (kgf¡cm2)

Very high > 2,200High 1,100-2,200Medium 550-1,100Low 280-550Very low <280

4 Reported construction characteristics are limited in number. Evaluations of rockunits, for the most part, are inferred from generalized conditions of structure, altera¬tion, hydrology and state-of-stress Specific conditions can change within short dis¬

tance. More renned engineering evaluations must be based on more detailed know¬ledge of geological conditions.

Inferred for intact rock Modulus is reduced by physical defects and chemical altera¬tion in rock, it differs with respect to bedding, foliation, or direction of principalresidual stress

Modulus class Range of static modulusof elasticity (kgfjcm2)

Very high >8 4x105High 5 6x105-8.4x10'Medium 2 8 x lO'-S 6 x 10'Low 7 x 10*-2.8 x 105

Very low <7 x lfjtNumber 1 indicates rock most difficult to drill Numbers increase with ease of drilling.The well-yield data used here are based on public-supply and industrial wells in whichthe maximum potential of the aquifer was being developed

54


BEDROCK MAP UNIT


Map Unit. Amphibolite, epidote amphibolite, and metamorphosedgabbro.

Equivalent geological unit.1 Baltimore gneiss (part); Brimfield for¬mation (part); Glastonbury gneiss (part); Maltby lakes volcan-ics (part); Marlboro formation (part); Middletown formation(part); Putnam gneiss (part); Tatnic hill formation (part); un¬

named units.Lithology. Massive to banded, tough, strong amphibolite, amphi¬

bolite schist, amphibolite gneiss, hornblende gneiss; in partmetagabbroic. Forms extensive thick layers, lenses and pods.Commonly epidote-bearing; much epidote-rich amphibolitegneiss, and pods of epidote; includes extensive thick light-red topink garnet-rich, layers. In places schistose toward margins;locally intruded by quartz diorite dykes.

Structure. Structure variable; rock ranges from massive to gneiss-ic. Large massive bodies rarely show folds, whereas smaller orlayered bodies commonly are complexly folded. Joints common¬ly persistent, but vary greatly in spacing.

Weathering. Weathers to sticky red clay south-west of glaciatedarea ; almost unweathered in glaciated area.

Topography. Hills to low mountains; rugged in places, especiallynear rivers.

Physicalproperties 2

Dry unit weight (kg per cubic metre). 3,000-3,200.Compressive strength.3 High to very high.

Engineering characteristics

Evaluation of rock for construction.4

Young's modulus of elasticity.5 High to very high.Relative drillabilityfi 2.

Excavation characteristics. Overbreak reported moderate to exces¬

sive depending on orientation of excavation to major joint sys¬

tems. Rock loads mostly slight. Swelling ground probable in wetshear zones. Contains fibrous minerals which may slow excava¬

tion by boring machine.

Hydrologie conditions1

Significant hydrolic features. Water occurs in weathered zone atshallow depth, probably not much below 45 m. Maximumyields from fault zones.

Permeability. Secondary. Primary fracturing; chemical weathering.Depth of wells. Range: 10-230 m. Median: 47.5 m.Yield of wells. Range: 2.2-675 litres per minute. Median: 54 litres

per minute.

1 . The stratigraphie nomenclature used in this report is that of the authors of the variousdata sources and does not necessarily conform with usage of the United States Geo¬logical Survey.

2. Physical data available only for some rock units; where data are lacking, the physicalproperties are inferred from comparisons with those of rock elsewhere that possess

similar composition, structure and geological histories3 Classification is for uniaxial compressive strength of intact rock. Strength is reduced

by physical defects and chemical alteration in rock, it may differ with respect tobedding, foliation or direction of principal residual stress.

Strength class Range of compressivestrength (kgf¡cm2)

Very high > 2,200High 1,100-2,200Medium 550-1,100Low 280-550Very low <280

4 Reported construction characteristics are limited in number. Evaluations of rockunits, for the most part, are inferred from generalized conditions of structure, altera¬tion, hydrology and state-of-stress Specific conditions can change within short dis¬

tance. More renned engineering evaluations must be based on more detailed know¬ledge of geological conditions.

Inferred for intact rock Modulus is reduced by physical defects and chemical altera¬tion in rock, it differs with respect to bedding, foliation, or direction of principalresidual stress

Modulus class Range of static modulusof elasticity (kgfjcm2)

Very high >8 4x105High 5 6x105-8.4x10'Medium 2 8 x lO'-S 6 x 10'Low 7 x 10*-2.8 x 105

Very low <7 x lfjtNumber 1 indicates rock most difficult to drill Numbers increase with ease of drilling.The well-yield data used here are based on public-supply and industrial wells in whichthe maximum potential of the aquifer was being developed

54

SURFICIAL DEPOSIT MAP UNIT



Symbol and designation. Qt. Younger ground moraine.Lithology. Till (GM, GC, SM).i Chiefly an unsorted mixture of

clay, silt, sand, gravel and boulders. Varies from a cohesive,moderately clayey material with embedded pebbles, cobbles andboulders (boulder clay) to a very-well-graded sand with gravel,cobbles, boulders and minor silt derived mostly from nearbybedrock. Stratification generally lacking, poor to crude wherepresent. Generally very compact, firm and friable; upper fewfeet may be somewhat loose. Colour varies with weathering (ox¬idation) and with colour of dominant source bedrock. Generallygrey when unweathered, buff to brown when oxidized; reddish-brown in areas of reddish-brown bedrock. Locally contains orunderlies thin lenticular sand and gravel. Overlain by manysmall, thin swamps containing muck and peat, and streamcourses with post-glacial alluvium that are not shown on map.Locally patchy; numerous bedrock exposures within unit notshown.

Thickness. Very irregular, generally less than 7 m. Unit normallythin to absent on hill crests and along major escarpments,thickness downslope to 15 m or more on lower slopes. Indrumlins may be 45 m thick or more.

Alteration. Upper 1-18 m oxidized; most stones unweathered ornearly so.

Topography. A nearly ubiquitous mantle overlying the bedrocksurface. Unusually thick till underlies streamlined hills, calleddrumlins, which may be as much as 45 m high; some drumlinshave a core of bedrock.

Yield of wells. Range: 4.5-68 litres per minute; median: 27 litresper minute.

Coefficient of permeability. Range: 0.8-180 litres per day persquare metre; median: .

Specific capacity6 (litres per minute per metre). Range : ; median:

Water-table conditionsSpecific yield.1 5-17 per cent.Free water content* 60-210 litres per cubic metre.Excavation permeability.9 5.5-190 litres per day per square metre.

Technical characteristics

Evaluation

Foundation conditions.2 Bearing capacity generally good because ofhigh density and poor sorting. Expansion negligible.

Excavation characteristics. Generally easy to moderately difficultto excavate with power equipment. Highly compacted till('hardpan'), and very strong and bouldery till can be trouble¬some to excavate without special equipment.

Slope stability* Cuts higher than 12 m generally require individualstability analysis. For lower slopes, 1.5 on 1 to 2 on 1 generallyconsidered safe. Vertical slopes up to 4.5 m common, particularlyin more cohesive clayey till.

General hydrological conditions*.*

Significant hydrologicalfeatures.* Small domestic supplies obtainedfrom dug wells. Unit functions as a confining layer over somebedrock aquifers.

1 Unified Soil Classification System adopted by Corps of Engineers, United StatesArmy. The Unified Soil Classification System, Waterways Experimental Station,Vicksburg, Miss , 1953, Vol 1, 30 p , 9 pi ; Vol 2, 1 1 p., 1 pi (Tech. Memo 3-357 )

Based on grain size, gradation, plasticity and compressibility of soil Symbols assignedare approximate, based upon limited test data.

2 Bearing capacity (numerical values (tons per square metre) applied to qualifyingadjectives) : very poor = less than 1 1 , poor = 1 1-43 , fair = 43-86 ; good = 86-350 , excel¬

lent = greater than 350 Compressibility = volume decrease in a soil mass in responseto an external load Expansion = volume increase that is a function of load, time,density, water content and type of clay minerals.

3. Cut slopes (numerical values, m degrees, applied to qualifying adjectives)' verti-cal = 90, near vertical = 80-89 , steep=45-80, moderate - 30-45 ; gentle = 0-30.

4. The well-yield data used in the preparation of this text are based on public-supply andindustrial wells in which the maximum potential of the aquifer was being developed(litres per minute).

5. Data given under general conditions should be used for calculations pertaining toartesian aquifers in tunnelling or deep excavations where it may not be possible todissipate the hydrostatic head.

6. Specific capacity is the discharge expressed as a rate of yield per unit of drawdown.Data used are selected to represent conditions of optimum well development andtherefore reflect aquifer characteristics.

7. The ratio of the volume of water which a saturated rock or soil will yield by gravity toits own volume, staled as a percentage Values used in this text are laboratory deter¬

minations or estimates based on field experience.8. Litres per cubic metre yielded by gravity drainage9. Rate of flow of water in litres per day through a cross section of 1 square metre under

a unit hydraulic gradient at prevailing water temperatures.

55

SURFICIAL DEPOSIT MAP UNIT



Symbol and designation. Qt. Younger ground moraine.Lithology. Till (GM, GC, SM).i Chiefly an unsorted mixture of

clay, silt, sand, gravel and boulders. Varies from a cohesive,moderately clayey material with embedded pebbles, cobbles andboulders (boulder clay) to a very-well-graded sand with gravel,cobbles, boulders and minor silt derived mostly from nearbybedrock. Stratification generally lacking, poor to crude wherepresent. Generally very compact, firm and friable; upper fewfeet may be somewhat loose. Colour varies with weathering (ox¬idation) and with colour of dominant source bedrock. Generallygrey when unweathered, buff to brown when oxidized; reddish-brown in areas of reddish-brown bedrock. Locally contains orunderlies thin lenticular sand and gravel. Overlain by manysmall, thin swamps containing muck and peat, and streamcourses with post-glacial alluvium that are not shown on map.Locally patchy; numerous bedrock exposures within unit notshown.

Thickness. Very irregular, generally less than 7 m. Unit normallythin to absent on hill crests and along major escarpments,thickness downslope to 15 m or more on lower slopes. Indrumlins may be 45 m thick or more.

Alteration. Upper 1-18 m oxidized; most stones unweathered ornearly so.

Topography. A nearly ubiquitous mantle overlying the bedrocksurface. Unusually thick till underlies streamlined hills, calleddrumlins, which may be as much as 45 m high; some drumlinshave a core of bedrock.

Yield of wells. Range: 4.5-68 litres per minute; median: 27 litresper minute.

Coefficient of permeability. Range: 0.8-180 litres per day persquare metre; median: .

Specific capacity6 (litres per minute per metre). Range : ; median:

Water-table conditionsSpecific yield.1 5-17 per cent.Free water content* 60-210 litres per cubic metre.Excavation permeability.9 5.5-190 litres per day per square metre.

Technical characteristics

Evaluation

Foundation conditions.2 Bearing capacity generally good because ofhigh density and poor sorting. Expansion negligible.

Excavation characteristics. Generally easy to moderately difficultto excavate with power equipment. Highly compacted till('hardpan'), and very strong and bouldery till can be trouble¬some to excavate without special equipment.

Slope stability* Cuts higher than 12 m generally require individualstability analysis. For lower slopes, 1.5 on 1 to 2 on 1 generallyconsidered safe. Vertical slopes up to 4.5 m common, particularlyin more cohesive clayey till.

General hydrological conditions*.*

Significant hydrologicalfeatures.* Small domestic supplies obtainedfrom dug wells. Unit functions as a confining layer over somebedrock aquifers.

1 Unified Soil Classification System adopted by Corps of Engineers, United StatesArmy. The Unified Soil Classification System, Waterways Experimental Station,Vicksburg, Miss , 1953, Vol 1, 30 p , 9 pi ; Vol 2, 1 1 p., 1 pi (Tech. Memo 3-357 )

Based on grain size, gradation, plasticity and compressibility of soil Symbols assignedare approximate, based upon limited test data.

2 Bearing capacity (numerical values (tons per square metre) applied to qualifyingadjectives) : very poor = less than 1 1 , poor = 1 1-43 , fair = 43-86 ; good = 86-350 , excel¬

lent = greater than 350 Compressibility = volume decrease in a soil mass in responseto an external load Expansion = volume increase that is a function of load, time,density, water content and type of clay minerals.

3. Cut slopes (numerical values, m degrees, applied to qualifying adjectives)' verti-cal = 90, near vertical = 80-89 , steep=45-80, moderate - 30-45 ; gentle = 0-30.

4. The well-yield data used in the preparation of this text are based on public-supply andindustrial wells in which the maximum potential of the aquifer was being developed(litres per minute).

5. Data given under general conditions should be used for calculations pertaining toartesian aquifers in tunnelling or deep excavations where it may not be possible todissipate the hydrostatic head.

6. Specific capacity is the discharge expressed as a rate of yield per unit of drawdown.Data used are selected to represent conditions of optimum well development andtherefore reflect aquifer characteristics.

7. The ratio of the volume of water which a saturated rock or soil will yield by gravity toits own volume, staled as a percentage Values used in this text are laboratory deter¬

minations or estimates based on field experience.8. Litres per cubic metre yielded by gravity drainage9. Rate of flow of water in litres per day through a cross section of 1 square metre under

a unit hydraulic gradient at prevailing water temperatures.

55


5.3.2.2 Special purpose, comprehensive, medium-scale map

Maps of Herceg Novy (Yugoslavia) at an approximate scaleof 1 : 2,300 showing lithology (upper map) and seismic micro-zoning (lower map) for urban planning

Legend

Geodynamic phenomena:

,^\"^ / Scarp of active landslide

Upper limit of beach cliff and limit of waveattack

Structural and tectonic phenomena :

, ^ Boimdary of engineering-geological complex

-> Bedding, dip and strike

,->''- Joint, dip and strike

^ Fault, dashed where supposed

^:r:^ Minor fault, dashed where supposed

JS^Reserve faults, major and minor, dashedwhere supposed

Legend

Terrain classified on the basis of stability :

tesi Unstable

[jiT 1 Unstable, partly stabilized

^^^ Potentially unstable

^^^ Conditionally stable (in conditions of predo-^^^ minantly horizontal relief)

^^ Stable

Other symbols:

O Exploration borehole

t Sample for geomechanical analysis

Trace of electrical resistivity traverse

Trace of seismic refraction profile

<W-

56


Lithological composition and some important properties of theengineering geological complexes (top map).

Map of seismic microzoning (bottom map) :

Limestone and chert. Limestone with beds and lensesof chert, silicified marlstone and claystoneLimestone is thinly to thickly bedded, tectonically morefractured, karstification rather poor, porosity fromfractured to cavernous, permeability irregular

Carbonate rocks undivided. Limestone with subordi¬nate dolomite, dolomitic limestone, sandy and marlylimestoneMechanically rather resistant, considerable karstifica¬tion, cavernous to fractured, mainly readily permeable;rockfalls and talus on steep slopes

Flysch and flyschoid rocks. Marly limestone, conglom¬erate, sandstone, marlstone, claystone and transitionaltypes, which occur rather irregularlyAlterations of platy, thin layered to laminated, rarelybedded to thickly bedded. Folded and fractured. Af¬fected by surface weathering and erosion; fractures im¬part irregular porosity, permeability irregular

Talus. Carbonate stony debris, sand and clay with frag¬ments and blocks of limestoneTalus has variable physical properties, prone to erosionand denudation processes, landsliding, etc.; unevenlyconsolidated, poorly graded and compacted, irregularporosity and permeability

Torrential stream deposits. Gravels, sands and clays,mainly carbonate materialsMaterials of variable grain size, poorly bedded andconsolidated, irregularly permeable. Variable in thick¬ness; contains organic matter

Littoral deposits. Boulders, gravels and sands, locallywith clay ; near the coast clay predominatesThe deposits are very variable in grain size, poorlycompacted, mainly saturated with water

Alluvial beach deposits. Silts and clays, rarely sandyand gravelly; some detritus of weathered flyschDeposits of variable grain size, poorly bedded, mainlycompressible, saturated sediments with variable physi¬cal properties

Colluvial deposits. Very heterogeneous, mainly coarsedetritus with blocksPoorly graded, seasonally saturated with groundwater,irregularly permeable and liable to continual sliding

10

Part of complexes of carbonate and limestones withcherts, tectonically moderately disturbed or in a zone ofhigh slopes (K = 0.05)

More fractured and tectonically disturbed parts ofcomplexes of carbonate and limestones with cherts,where large blocks are liable to fall (K = 0.06)

Complex of flysch and flyschoid rocks, small isolatedmasses of carbonate rocks on flysh, as well as highlyconsolidated semi-cohesive and uncohesive materials inthe zone of surface weathering (K = 0.08)

Well consolidated parts of slope deposits, well gradedand permeable, as well as proluvial and alluvial depo¬sits where water table is deeper than 2 m (K = 0.10)

Poorly graded and predominantly impermeable parts oftalus on slopes with inclinations greater than 12°, as

well as parts of torrent and stream deposits of veryheterogeneous composition, with water table less than2mdeep(K = 0.12)

Highly compressible and saturated littoral deposits andcolluvial deposits of variable permeabihty (K = 0.12)

Note: K = coefficient of seismicity

Comment

The single-map sheet, measuring 970 x 675 mm, is printedin colour. It includes two maps of the area at a scale of1 : 25,000. The first, part of which is presented here in theupper illustration, is a lithological map with eleven horizontalcross-sections. The second, presented in part in the lowerillustration, is a map of seismic microzoning on which themap units are defined in terms of coefficient of seismicity.As an overprint to this map terrain is classified accordingto stability.

Also provided on the map sheet is a small-scale, 1 :

100,000, map of seismic classification according to maximumintensity with epicentres for the period 1853-1970. Isolinesare also given delimiting areas of different seismic intensityfor the period 1667-1970.

A large-scale cross-section shows an interpretation ofthe structure of a selected area effected by multiple landslid¬ing, and the bases for stability calculations.

The map sheet is an excellent example of the use of anextended descriptive legend, examples of which are repro¬duced here. Symbols for hydrological and hydrogeologicalfeatures are also used on the pubUshed sheet.

Extract from the Engineering Geological Map of the

Urban Area of Herceg Novy, Jugoslavia, compiled at a scale

of 1 :25,000 by D. Gojgic and M. Lazic in the Institute forGeological and Geophysical Research, Beograd, 1971.

57


5.3.2.3 Specialpurpose, comprehensive, large-scale map

Map of a mining area, originally produced at 1 : 10000,reproduced here at 1 : 100,000 approximately

CommentThe map illustrated here is one of a pair which shows theengineering and geological conditions of surface strata; theother (Golodkovskaja and Demidyuk, 1970, Fig. 2) providesinformation about the engineering geology of the bedrock.

This map, of an area underlain by a mineral deposit in apermafrost region, has been used in the design and construc¬tion of mining and industrial works, urban, road and otherstructures required for the development of the deposit. Itshows the age and genesis of the uppermost and underlyingdeposits, their lithology, thermal condition, frozen water(ice) content, range of average annual rock temperature,depth of seasonal and permanent frozen ground, depth of

frozen and partly frozen water, thickness of Quaternary de¬

posits, and contemporary geological processes and phenome¬na. It also gives an evaluation of the area for constructionpurposes.

Despite the abundance of symbols the map is easily un¬

derstood in this black-and-white version; legibility could beimproved by the use of colour.

From the point of view of engineering-geological carto¬graphy, the map illustrates an interesting application of the'stripe method' (Section 4.5) of indicating the nature ofdeposits underlying the uppermost beds combined with otherinformation. Shading in the stripes (symbols 7 and 8) illus¬trates the distribution of marine Upper Quaternary and Per-mo-Triassic rocks; the direction and width of the stripes(symbols 9 to 12) indicates the average annual temperaturerange of the rocks; while the three degrees of spacing of thestripes (symbol 13; here illustrated as applied to sym¬

bol 1 1(a), but applicable to the whole range of symbols 9 to

58



Map of a mining area, originally produced at 1 : 10000,reproduced here at 1 : 100,000 approximately

CommentThe map illustrated here is one of a pair which shows theengineering and geological conditions of surface strata; theother (Golodkovskaja and Demidyuk, 1970, Fig. 2) providesinformation about the engineering geology of the bedrock.

This map, of an area underlain by a mineral deposit in apermafrost region, has been used in the design and construc¬tion of mining and industrial works, urban, road and otherstructures required for the development of the deposit. Itshows the age and genesis of the uppermost and underlyingdeposits, their lithology, thermal condition, frozen water(ice) content, range of average annual rock temperature,depth of seasonal and permanent frozen ground, depth of

frozen and partly frozen water, thickness of Quaternary de¬

posits, and contemporary geological processes and phenome¬na. It also gives an evaluation of the area for constructionpurposes.

Despite the abundance of symbols the map is easily un¬

derstood in this black-and-white version; legibility could beimproved by the use of colour.

From the point of view of engineering-geological carto¬graphy, the map illustrates an interesting application of the'stripe method' (Section 4.5) of indicating the nature ofdeposits underlying the uppermost beds combined with otherinformation. Shading in the stripes (symbols 7 and 8) illus¬trates the distribution of marine Upper Quaternary and Per-mo-Triassic rocks; the direction and width of the stripes(symbols 9 to 12) indicates the average annual temperaturerange of the rocks; while the three degrees of spacing of thestripes (symbol 13; here illustrated as applied to sym¬

bol 1 1(a), but applicable to the whole range of symbols 9 to

58


12 as shown on the map) indicate the frozen water (ice)content of the rocks.

A map of this type has reached the practical limit ofcomplexity and would need to be accompanied by comple¬mentary hydrogeological and topographical maps (2.3.2.4)and auxiliary maps showing for example the compositionand thickness of the surficial deposits (2.3.2.3).

The original version of this map was published as

Figure 1 : 'Montage of Engineering and Geological Map ofQuaternary Deposits with Elements of Territorial Engineer¬ing and Geological Evaluation for Ground Construction', toaccompany the paper by G. A. Golodkovskaja andL. M. Demidyuk, "The Problems of the Engineering andGeological Mapping of Deposits of Mineral Resources in theArea of Eternal Frost' Proceedings of the first InternationalCongress of the International Association of Engineering Geol¬

ogy, Paris, 1970, Vol. 2, p. 1049-68. The version publishedhere has been redrawn and slightly modified.

Legend1Genetic types and age of deposits:

I Eluvial, contemporary (eQiv)

li

Il Recent alluvium (alQiv)

n

Deltaic, Upper Quaternary (dtQm)

Lithology:

^1b¿

V7,¿à

Alluvial, Upper Quaternary (alQm)

Diluvial, Upper Quaternary (dQm)

Lacustrine, Upper Quaternary (lQni)

H Glacial, marine Upper Quaternary (glmQm)

Volcanogenic Permian-Triassic (P2-T1)

Average annual range of temperature of rocks :

0°to 1°

; e

(a) Io to 2°(b) + Io to +2°

(a) 3° to i?(b) +3° to +5°

I J I +5° to +7°

no*Frozen water (ice) content of rocks:

(a) Low (b) Medium (c) HighB b c

1. Note that the symbols in the legend have been reduced more than the equivalent mapsymbols.

Rock debris with loam matrix

Clay, loam with rock debris

Inequigranular sand

Pebbles and sand matrix

Clay

Recent geological processes :

I Formation of fissures under conditions of frost

-Í

Swelling

Melting of ice intrusions

Solifluction

Other symbols :

I- 1 s»0-7»

ES,

Depth of seasonal melting in metres (numerator)Depth of permanently frozen ground in metres (deno¬minator)

Depth of frozen water (numerator)

Thickness of Quaternary deposits

Temperature boundaries

P^ I Boundaries of underlying rocks

Lithological boundaries

Boundaries of engineering and geological areas:

Requiring no special engineering preparation

XLE Requiring engineering preparation

EL Requiring very complicated engineering preparation

59


12 as shown on the map) indicate the frozen water (ice)content of the rocks.

A map of this type has reached the practical limit ofcomplexity and would need to be accompanied by comple¬mentary hydrogeological and topographical maps (2.3.2.4)and auxiliary maps showing for example the compositionand thickness of the surficial deposits (2.3.2.3).

The original version of this map was published as

Figure 1 : 'Montage of Engineering and Geological Map ofQuaternary Deposits with Elements of Territorial Engineer¬ing and Geological Evaluation for Ground Construction', toaccompany the paper by G. A. Golodkovskaja andL. M. Demidyuk, "The Problems of the Engineering andGeological Mapping of Deposits of Mineral Resources in theArea of Eternal Frost' Proceedings of the first InternationalCongress of the International Association of Engineering Geol¬

ogy, Paris, 1970, Vol. 2, p. 1049-68. The version publishedhere has been redrawn and slightly modified.

Legend1Genetic types and age of deposits:

I Eluvial, contemporary (eQiv)

li

Il Recent alluvium (alQiv)

n

Deltaic, Upper Quaternary (dtQm)

Lithology:

^1b¿

V7,¿à

Alluvial, Upper Quaternary (alQm)

Diluvial, Upper Quaternary (dQm)

Lacustrine, Upper Quaternary (lQni)

H Glacial, marine Upper Quaternary (glmQm)

Volcanogenic Permian-Triassic (P2-T1)

Average annual range of temperature of rocks :

0°to 1°

; e

(a) Io to 2°(b) + Io to +2°

(a) 3° to i?(b) +3° to +5°

I J I +5° to +7°

no*Frozen water (ice) content of rocks:

(a) Low (b) Medium (c) HighB b c

1. Note that the symbols in the legend have been reduced more than the equivalent mapsymbols.

Rock debris with loam matrix

Clay, loam with rock debris

Inequigranular sand

Pebbles and sand matrix

Clay

Recent geological processes :

I Formation of fissures under conditions of frost

-Í

Swelling

Melting of ice intrusions

Solifluction

Other symbols :

I- 1 s»0-7»

ES,

Depth of seasonal melting in metres (numerator)Depth of permanently frozen ground in metres (deno¬minator)

Depth of frozen water (numerator)

Thickness of Quaternary deposits

Temperature boundaries

P^ I Boundaries of underlying rocks

Lithological boundaries

Boundaries of engineering and geological areas:

Requiring no special engineering preparation

XLE Requiring engineering preparation

EL Requiring very complicated engineering preparation

59


5.3.2.4 Special purpose, comprehensive, large-scale map

Map scale 1 : 1,550 approximately

IÛlCross-section A-A". Engineering-geological cross-section (with indices of saturation, consistency, loess collapsibility, strength anddeformability).

101

60


5.3.2.4 Special purpose, comprehensive, large-scale map

Map scale 1 : 1,550 approximately

IÛlCross-section A-A". Engineering-geological cross-section (with indices of saturation, consistency, loess collapsibility, strength anddeformability).

101

60


Legend

®

Ó

ó

\1.0\

_fM_n102.65^

01M32

13 281108.04

IQtn

«lQn.

' \-iWp-i'

í$ü1 1 ' 1

'i'i1

¡!¡i¡

ó '.o-:'

Boreholes, 5-10 m in depth



Boreholes deeper than 50 m

Borehole with long-term observations of thegroundwater table

Borehole for pumping tests

Old karst sinkhole

Index of consistency (after Makeev)

Degree of saturation

'K' coefficient of macroporosity (in loessmaterials)

Internal friction angle

Cohesion, kg. cm'1

Modulus of compressibility in mm.m"'(loadingat 2 kg.cm-2)

Surface isolines of the zone, where clayeymaterials have a plastic consistency

Groundwater table

Borehole profile, where samples were taken forlaboratory tests

Southern boundary of Neogene

Hydroisolines on 25 September 19-, at 1 mintervals

Geological cross-section lines

Depth of shallow groundwater (in metres) fromthe surface

Elevation of groundwater table (a.s.l.)

Borehole numberElevation (a.s.l.)

Shaft number

Elevation (a.s.l.)

Surface contours (gradation of 0.5 m)

Top soil

Peat, greyish-brown

eQ3 Peaty clayey silt, greenish-grey

Sandy silt, loess-like, yellowish-brown

Silt, loess-like, yellow-brown

alQ2 Clayey silt, loess-like, yellowish-brown

Clayey silt, loess-like, grey

Sandy clay, greenish-grey

Basal conglomerate

Comment

The map is accompanied by an axonometric three-dimen¬sional model, and tables of characteristics of map rock unitsand characteristics of delimited engineering-geological dis¬

tricts.In the table of rock characteristics each distinctive en¬

gineering-geological type, shown in the map and cross-sec¬

tion, is described in detail as far as the lithological characterand engineering classification properties are concerned (ac¬

cording to building standards), physical properties (grainsize, specific gravity, bulk density, porosity, natural moisturecontent, degree of saturation, plasticity limits, consistency,collapsibility), and mechanical properties (angle of internalfriction, cohesion, modulus of compressibility at 2 and4 kg.cm-2 loading).

The table of characteristics of individual engineering-geological districts contains the following data: descriptionof the lithological profile of foundation soils, hydrogeologicalconditions, geodynamic phenomena, collapsibility ofmaterials,other special local characteristics, as well as engineeringrecommendations.

This is one of the first published engineering-geologicalmaps, a pioneering effort which is very close in basic prin¬ciples of mapping and presentation of data to the proposalsin this guidebook. Made for the practical purpose of theengineering design of an industrial plant, the map was publish¬ed as an example of mapping by I.V. Popov, R.S. Kats,A. K. Korikovskaya, and V. P. Lazareva in 1950 in their bookThe Techniques of Compiling Engineering Geological Maps.

Their map ofengineering geological conditions, reproduc¬ed here in black-and-white, had, in the original, a territorialdivision into engineering-geological districts distinguished bycolours.

61


Legend

®

Ó

ó

\1.0\

_fM_n102.65^

01M32

13 281108.04

IQtn

«lQn.

' \-iWp-i'

í$ü1 1 ' 1

'i'i1

¡!¡i¡

ó '.o-:'




Boreholes deeper than 50 m

Borehole with long-term observations of thegroundwater table

Borehole for pumping tests

Old karst sinkhole

Index of consistency (after Makeev)

Degree of saturation

'K' coefficient of macroporosity (in loessmaterials)

Internal friction angle

Cohesion, kg. cm'1

Modulus of compressibility in mm.m"'(loadingat 2 kg.cm-2)

Surface isolines of the zone, where clayeymaterials have a plastic consistency

Groundwater table

Borehole profile, where samples were taken forlaboratory tests

Southern boundary of Neogene

Hydroisolines on 25 September 19-, at 1 mintervals

Geological cross-section lines

Depth of shallow groundwater (in metres) fromthe surface

Elevation of groundwater table (a.s.l.)

Borehole numberElevation (a.s.l.)

Shaft number

Elevation (a.s.l.)

Surface contours (gradation of 0.5 m)

Top soil

Peat, greyish-brown

eQ3 Peaty clayey silt, greenish-grey

Sandy silt, loess-like, yellowish-brown

Silt, loess-like, yellow-brown

alQ2 Clayey silt, loess-like, yellowish-brown

Clayey silt, loess-like, grey

Sandy clay, greenish-grey

Basal conglomerate

Comment

The map is accompanied by an axonometric three-dimen¬sional model, and tables of characteristics of map rock unitsand characteristics of delimited engineering-geological dis¬

tricts.In the table of rock characteristics each distinctive en¬

gineering-geological type, shown in the map and cross-sec¬

tion, is described in detail as far as the lithological characterand engineering classification properties are concerned (ac¬

cording to building standards), physical properties (grainsize, specific gravity, bulk density, porosity, natural moisturecontent, degree of saturation, plasticity limits, consistency,collapsibility), and mechanical properties (angle of internalfriction, cohesion, modulus of compressibility at 2 and4 kg.cm-2 loading).

The table of characteristics of individual engineering-geological districts contains the following data: descriptionof the lithological profile of foundation soils, hydrogeologicalconditions, geodynamic phenomena, collapsibility ofmaterials,other special local characteristics, as well as engineeringrecommendations.

This is one of the first published engineering-geologicalmaps, a pioneering effort which is very close in basic prin¬ciples of mapping and presentation of data to the proposalsin this guidebook. Made for the practical purpose of theengineering design of an industrial plant, the map was publish¬ed as an example of mapping by I.V. Popov, R.S. Kats,A. K. Korikovskaya, and V. P. Lazareva in 1950 in their bookThe Techniques of Compiling Engineering Geological Maps.

Their map ofengineering geological conditions, reproduc¬ed here in black-and-white, had, in the original, a territorialdivision into engineering-geological districts distinguished bycolours.

61



Engineering geological map of Hannover at 1 : 6,350

CommentA typical example of an urban engineering geological mapbuilt up from extensive borehole observations and other nearsurface observations. Particular attention is paid to areas ofartificial fill and the natural surficial deposits of importancein foundation engineering. Solid geology and hydrogeologi¬cal conditions, both natural and man-made, are also shown.

Parts of the engineering-geological (1:10,000) andgroundwater (1 : 20,000) sheets of the new engineering geo¬

logical map of Hannover, 1970, here combined in a simpli¬fied single sheet at a scale of 1 : 6,350.

62


Legend

Infilling of the old town-moat (about 1550-80)KMest

Marly hmestone, compact, widely jointed, jointsin part water-bearing; locally flaggy, Kca 1-1-2

(Campanian, Upper Chalk) on the geologicalmap

Abandoned meander of the Leine, ponds and for¬tification moats, silted up, in part infilled Tst

Mudstone, compact (in even beds more than100 m thick) with a covering of unconsolidatedsoil, the uppermost 1-2 m mainly stiff plasticclay, softened, generally widely jointed

Embankment, tipped and poorly compacted soil K45XMI7

B47

Sampling point for grain size (K), mineral (M)and soil mechanics (B) analysis

X G43 Site investigation

fSmS"S"

General thin fill within the old town

E5Gravel (more than 2 m and up to 3 m thick), withfew to many lenses of fine to coarse sand with fineto medium gravel (fluvio-glacial sand), dry todamp, round to angular, of varied lithology

Fine sand with a little medium sand (up to 2 mthick, round and equigranular : = dune sand)generally overlying alluvial sand, mainly dry

30

Highest known groundwater level contour, withheight in metres above datum, based on manyyears of observation in good water-bearing beds,generally in sands and gravels in part interstrafi-fied with loam and clays

Approximate groundwater contours

Ancient principal main drainage channel, onlyused occasionally for drainage

Thickness, or the sum of the thicknesses, of wa¬

ter-bearing strata

fstSuKi

\fSmSV

Alluvial loam, fine sand with clay (up to 5.5 mthick) uppermost metre generally clayey with de¬

posits of peat (up to about 1 m) and sapropelicmud (up to 1 .2 m thick) over gravel

Fine sand with a httle medium sand over alluvialloam

Observation well (since 1941)

Observation well (1943-M)

ifi'-'i-'-i '': ''' ;! Direction of groimdwater flow

Sample site for groundwater analysis

63



5.4.1 INTERPRETATIVEGEOLOGICAL MEDIUM-SCALE MAP

Legend

Qu

Qmi

Pleistocene

Qu Undivided Quaternary deposits

Qsu San Antonio formation. Uppermember; clay, silt, sand, andgravel

Pliocene (?) Tl Leona Rhyolite

The map has been redrawn and slightly simplified from mapGQ-769, Areal and Engineering Geology of the Oakland East Quad¬

rangle, California, by Dorothy H. Radbruch 1969, United StatesGeological Survey, Washington, D.C. An explanatory pamphletaccompanies the map.

The map is reproduced here at a scale of 1 : 20,000.

Q Upper Jurassic Jk Knoxville formation. Shale,sandstone, and minor conglom¬erate

^t^f

J' ** I^ I^W*»^Jj

'*^^^y^

^ú:X^^^y

'> 'i \t *^ V ^ *'*^.?^j,,_^^|i3^B

%.\/j' 'M'3« î^/ ji'^^ \sN\ jVvî.^/^-/"ii'' ¿f Jâfiiilv'^ KTvj 1 «Nfc:Vjt /^ .^\j# "'s -^îvC^?*^ ^ ^t "ô^ /Il*^Xy^/'x»?^\w^^Â"lÂA^-^*âHK

'^j^^Sr^ J'^jaWÇ ol^f>d«Sw!^^îlk3C >

^'vo^^^'^v^^ «awî/^^^

O^ fiftï arft^'^jitV ^^'^ ^<ry im [M) 1 : 4 n#^8â^ ^'^'^^^^^P^t fl 1^' v^ ^^ä'V^'^. ^%.j^^'2¿'-^^\^y'yWv^r: ^ ti srty W^'\ii'^5wr7<i^Sry^«i^'^/%/^y$'^9, 2 b tt et V *\^y^ / X^î*''^^'''^^J^ri^ß 1 1 «1 V cl t i\i A H'^Crf" / C^^SlSik ií"'''^ '^S f t cl w t ,*^ -i^ J^\ / f-'^^ÎWÎ

/

^^^h^^^

^¡^'«Ä. -X.'^^sJU^\ ^î^rV ^=%áá||gli Y^^^^^l

s\\^<''V'^\6^^ffy'>vu^1iu|ËiJ^^vjvxt'i^'rcf^^mii.

*^î^^^^^^ O.S t. U.^tiAAX^?*^^ kíY cl ,«d r(,: 5 5 f. Ï^^Mflntjí Qí Util ttiiiiXirt^*^.'*' =-"^'^' "'^''' JKV^^H

^.''^lÎ- ^

\^ ^' - E lov S ft '110 2-5 "sdi

^ ^^

<rl Lv s ¿ifîd rk 'ra(^;'2?6Jp^rtÔ^7jKi^^.,^Mj\ !.l 1 fi tt t(v ^<}V '!' -^St^j^^ ^X^ ^^

Uv '^1 1 s tl ci: 85 fi ( Wl^lfVJSçf^^Î^í'cU't^á^ idy <jf^ ^^^î:Mr Jç ,JÂ^\ ,^%í¡^

fi ft ^^^^^''W^^î^^J^y^r^^r^^^^^^JtCl: 2 ft W^nrJ^y'y^^^^^^^^^^\¿\j

' IH/^^^\ vS^n^^ 1

í'^'^írvAJWlí\ J^ V,X\^ 7. ^ ïSf sltVCI « rk ttig 1(1117) \\ V>iÇ^ V\\ \îfP \j^\^%^ 10 f' *'iv et, wistef ai 8 ft

^^.íi^^-^ is f1 sdy dA

-"' /^ 'A âl^^ " \ \ïk 1

Qii

HAYWJUIO FAULT tOMOu

tTT

64


Legend

Contact Long-dashed where approximately located; colourboundary without contact line where hypothetical

ifi__7__Fault, showing dip. Long-dashed where approximate¬ly located; queried where probable

i" Strike and dip of beds

*" Approximate attitude of beds determined from aerialphotographs

LandslideThe symbol marks the approximate location of the landslide. Sizeof the symbol bears no relation to areal extent of the slide. Thelandslides as located on the map constitute a record of past slopefailures and are not by themselves proof of present or future slopeinstability.

Every landslide shown on the map was well defined and easilyobservable at the time of the study; however, not every landslide inthe area is shown on the map. Therefore, although a landslideexists (unless it has since been'removed by construction activity) atevery point where one is shown on the map, it does not follow thatthere are no landslides elsewhere on the map.

AbbreviationsElevations given below are to nearest foot. Thickness figures in logsare to the nearest 0.5 ft. Only the type of material encountered isgiven; descriptive details are omitted to conserve space. Thefollowing abbreviations are used in logs: ct, chert; cl, clay; cly,clayey; c, coarse; decomp, decomposed; f, fine; frag, fragment(s);gr, gravel; gry, gravelly; Ige, large; lm, loam; mtl, material; mat,matter; med, medium; mise, miscellaneous; org, organic; pt, peat;peb, pebble(s); r, red; rk, rock(s); s, sand; ss, sandstone; sdy,sandy; sp, serpentine; sh, shale; shl, shell(s); si, silt; slty, silty; sm,small; tr, trace; ve, vegetable; w, with; weath, weathered.

83® Site of boringLogs of borings are shown on the map where possible; wherespace does not permit showing the log on the map, it is givenbelow. Abbreviations used in logs are explained below.Number of item below refers to site number on map.85. Elev. 383 ft. 9 ft sdy cl ande to f s (fill); 9 ft gr-s-cl mix; 6 ft cl;11 ft sdy cl w tr f gr and si; 21 ft cl w s; 7 ft slty cl w f gr;14 ft gr-s-cl mix.

Location of consolidation test

65


Legend

Contact Long-dashed where approximately located; colourboundary without contact line where hypothetical

ifi__7__Fault, showing dip. Long-dashed where approximate¬ly located; queried where probable

i" Strike and dip of beds

*" Approximate attitude of beds determined from aerialphotographs

LandslideThe symbol marks the approximate location of the landslide. Sizeof the symbol bears no relation to areal extent of the slide. Thelandslides as located on the map constitute a record of past slopefailures and are not by themselves proof of present or future slopeinstability.

Every landslide shown on the map was well defined and easilyobservable at the time of the study; however, not every landslide inthe area is shown on the map. Therefore, although a landslideexists (unless it has since been'removed by construction activity) atevery point where one is shown on the map, it does not follow thatthere are no landslides elsewhere on the map.

AbbreviationsElevations given below are to nearest foot. Thickness figures in logsare to the nearest 0.5 ft. Only the type of material encountered isgiven; descriptive details are omitted to conserve space. Thefollowing abbreviations are used in logs: ct, chert; cl, clay; cly,clayey; c, coarse; decomp, decomposed; f, fine; frag, fragment(s);gr, gravel; gry, gravelly; Ige, large; lm, loam; mtl, material; mat,matter; med, medium; mise, miscellaneous; org, organic; pt, peat;peb, pebble(s); r, red; rk, rock(s); s, sand; ss, sandstone; sdy,sandy; sp, serpentine; sh, shale; shl, shell(s); si, silt; slty, silty; sm,small; tr, trace; ve, vegetable; w, with; weath, weathered.

83® Site of boringLogs of borings are shown on the map where possible; wherespace does not permit showing the log on the map, it is givenbelow. Abbreviations used in logs are explained below.Number of item below refers to site number on map.85. Elev. 383 ft. 9 ft sdy cl ande to f s (fill); 9 ft gr-s-cl mix; 6 ft cl;11 ft sdy cl w tr f gr and si; 21 ft cl w s; 7 ft slty cl w f gr;14 ft gr-s-cl mix.

Location of consolidation test

65


Generalized description of engineering properties of map units ]

Map unit General lithologiedescription

Topographic form

Undivided Quaternarydeposits (Qu)

San Antonio formation.Upper member (Qsu)

Composition and physical properties vary. Consist predominantly ofTemescal formation. Probably include covered or unrecognized San

Antonio formation and gravel, sand and clay (Qg), as well as recentalluvium and colluvium, and artificial fill. Symbols for Qtc, Qts, andQtb shown in parentheses where these units can be positively identified(see Temescal formation)

Clay, silt, sand, and gravel. Some pebbles soft; most firm. Most beds con¬

tain flakes and pebbles of white Claremont chert, some gravel almostentirely chert. Contains montmorillonite clay. Pale-yellowish-brownto greyish-orange. Consolidation varies, some layers loose, uncon¬solidated. Three consolidation tests on clay layers showed compressionof 4 to 6 per cent. Maximum thickness unknown. May includesome Temescal formation and lower member where exposures toopoor to differentiate units

Primarily in valleys and on gentleslopes between San Francisco Bayand the Berkeley Hills

Primarily in rather steep dissectedhilly areas between San FranciscoBay and steep front of BerkeleyHills

Leona rhyolite (TT) Rhyolite. Fresh rock light-grey to greenish- or hght-bluish-grey,weathers to white or dark-yellowish-orange, may be iron-stainedreddish-orange. Fresh rock contains abundant pyrite in many places.Contains a small amount of glass. Sheared and fractured. May includesmall amounts of Franciscan and Knoxville sandstone and shale toosmall to show on the map. Much of rhyolite apparently intrusive(Case, 1963); in places intruded overlying Knoxville shale, now bakedand contorted at contact

Forms steep knobby dissectedhills

Knoxville formation (Jk) Shale, olive-grey, fissile; sandstone, fine- to medium-grained, olive-grey; also includes pebble conglomerate in dark shale or sandstonematrix, minor concretionary limestone, and lignite. Some shale massive,some interbedded with sandstone. Shale contains abundant Buchtapiochii. Includes younger ¿Ji/cA/a-bearing marine sedimentary rocksdescribed by Case (1968). Thickness and stratigraphie relations un¬

known

Generally forms valleys, becausesoft shales of formation are easilyeroded

Faulting : The rocks of most of the above units have been compressed into northwest-trending folds and cut by numerous faults.The fractured rocks along any of the faults mentioned above may form passages for ground water, and cuts made across them may require

draining; the soft sheared rocks are also subject to landsliding.Severe earthquakes were caused by movement along faults within the Haywardfault zone in 1836 and 1868. Therefore, the entire length of the

Haywardfault zone in this quadrangle can be assumed to be active.Slow tectonic movement, or creep, is at present taking place at several locations along the Hayward fault zone, with resultant damage to

manmade structures which cross the line of creep. Both the Claremont water tunnel and the drainage culvert under the University ofCalifornia stadium have been damaged by this slow movement along a fault plane or band of shearing within the Hayward fault zone.It is not known whether creep is occurring along the fault zone elsewhere in this quadrangle, although discrepancies recently noted inrechecks of survey lines crossing the zone at 98th Avenue and at Lincoln Avenue may indicate right-lateral movement within the fault zoneof approximately 0.1 to 0.15 ft in 10 years.

Structures which lie within or cross the Hayward fault zone may not only be damaged by sudden movement, offset, and rupture along a faultat the time of an earthquake originating in the fault zone, but may also be subject to constant strain and damage due to the opposite sides offaults within the zone continuously moving very slowly in opposite directions.

66


Generalized description of engineering properties of map units ]

Map unit General lithologiedescription

Topographic form

Undivided Quaternarydeposits (Qu)

San Antonio formation.Upper member (Qsu)

Composition and physical properties vary. Consist predominantly ofTemescal formation. Probably include covered or unrecognized San

Antonio formation and gravel, sand and clay (Qg), as well as recentalluvium and colluvium, and artificial fill. Symbols for Qtc, Qts, andQtb shown in parentheses where these units can be positively identified(see Temescal formation)

Clay, silt, sand, and gravel. Some pebbles soft; most firm. Most beds con¬

tain flakes and pebbles of white Claremont chert, some gravel almostentirely chert. Contains montmorillonite clay. Pale-yellowish-brownto greyish-orange. Consolidation varies, some layers loose, uncon¬solidated. Three consolidation tests on clay layers showed compressionof 4 to 6 per cent. Maximum thickness unknown. May includesome Temescal formation and lower member where exposures toopoor to differentiate units

Primarily in valleys and on gentleslopes between San Francisco Bayand the Berkeley Hills

Primarily in rather steep dissectedhilly areas between San FranciscoBay and steep front of BerkeleyHills

Leona rhyolite (TT) Rhyolite. Fresh rock light-grey to greenish- or hght-bluish-grey,weathers to white or dark-yellowish-orange, may be iron-stainedreddish-orange. Fresh rock contains abundant pyrite in many places.Contains a small amount of glass. Sheared and fractured. May includesmall amounts of Franciscan and Knoxville sandstone and shale toosmall to show on the map. Much of rhyolite apparently intrusive(Case, 1963); in places intruded overlying Knoxville shale, now bakedand contorted at contact

Forms steep knobby dissectedhills

Knoxville formation (Jk) Shale, olive-grey, fissile; sandstone, fine- to medium-grained, olive-grey; also includes pebble conglomerate in dark shale or sandstonematrix, minor concretionary limestone, and lignite. Some shale massive,some interbedded with sandstone. Shale contains abundant Buchtapiochii. Includes younger ¿Ji/cA/a-bearing marine sedimentary rocksdescribed by Case (1968). Thickness and stratigraphie relations un¬

known

Generally forms valleys, becausesoft shales of formation are easilyeroded

Faulting : The rocks of most of the above units have been compressed into northwest-trending folds and cut by numerous faults.The fractured rocks along any of the faults mentioned above may form passages for ground water, and cuts made across them may require

draining; the soft sheared rocks are also subject to landsliding.Severe earthquakes were caused by movement along faults within the Haywardfault zone in 1836 and 1868. Therefore, the entire length of the

Haywardfault zone in this quadrangle can be assumed to be active.Slow tectonic movement, or creep, is at present taking place at several locations along the Hayward fault zone, with resultant damage to

manmade structures which cross the line of creep. Both the Claremont water tunnel and the drainage culvert under the University ofCalifornia stadium have been damaged by this slow movement along a fault plane or band of shearing within the Hayward fault zone.It is not known whether creep is occurring along the fault zone elsewhere in this quadrangle, although discrepancies recently noted inrechecks of survey lines crossing the zone at 98th Avenue and at Lincoln Avenue may indicate right-lateral movement within the fault zoneof approximately 0.1 to 0.15 ft in 10 years.

Structures which lie within or cross the Hayward fault zone may not only be damaged by sudden movement, offset, and rupture along a faultat the time of an earthquake originating in the fault zone, but may also be subject to constant strain and damage due to the opposite sides offaults within the zone continuously moving very slowly in opposite directions.

66


Weathering and soil development Workability Slope stability and foundation conditions Dry density2 moisturecontent and UnifiedSoil Classification3

Remarks (includes use andearthquake stability)

Soil may be as much as 3ft thick.In places soil clayey, shrinks andswells; may cause damage tobuildings

Can be moved withhand or power tools

Depend on composition; gen¬

erally good. Slides have formedwhere colluvium apparently deriv¬edfrom gabbro

Varies Mapped with Temescal formation in Oak¬land West quadrangle(Radbruch, 1957)

Soil as much as 3 ft thick inplaces. Soil swells and shrinks withseasonal moisture changes andmay cause damage to buildings;may creep on slopes

Can be moved withhand tools

Weathering as much as 30 ft deep;highly weathered rock consists ofloose fragments in clay matrix.Soil generally lacking or less than18 in thick; in ravines may bemore than 12 ft thick

Depth of weathering irregular;may be 20 ft or more in places.Some weathered rock firm, mostsoft, clayey. Soil commonly 1-3 ftthick

Can generally be mov¬ed with power equip¬ment; in some placesrequires blasting

Can be moved withpower equipment

Large slides have formed in thisunit. Factors contributing to slideprobably include presence ofmontmorillonite clay and alter¬nating poorly consolidated sandand clay; steep slopes; andgroundwater. Generally suitablefoundation material for lightstructures where slopes are notsteep

Slope stability and foundationconditions good. Rare debrisslides observed where rock exces¬

sively fractured and weathered

Slope stability and foundationconditions generally fair; minorsloughing in cuts

1.68; 18 percent (77: 1.45-1.97; 8-30 percent) GM-CH

2.59 (s); 0.1 percent; 99(weathered);20 per cent(3:1.57-1.63;9-27 per cent)

2 56 (s)(ss);1.4 per cent;1.86 (weather¬ed sh); 15 percent (3: 1.81-1.92; 13-19 percent)

Crushed Leona rhyo¬lite is a major sourceof fill and base rock;pyrite formerly minedfor sulfur ; runoff fromrhyolite hills very acidand corrodes concretesewer pipe. Some slo¬

pes so steep that de¬

velopment may be dif¬ficult

May squeeze in tunnelswhere sheared

Text printed in italics indicates geologic conditions that may be critical to planning, design, and construction of engineering worksDry density (italic) expressed in tonnes per cu m, based on one sample of fresh rock unless otherwise noted Number of samples and range of dry density and moisture contentgiven in parentheses (12 169-1 74, 17-20 per cent) (s) indicates sample collected at the surface Moisture content (per cent) generally higher for subsurface samples of rocksthan for those collected at the surfaceUnified Soil Classification (letter symbol) given where applicable (United States Army, Corps of Engineers, 1953, The Unified Soil Classification System, United States Army, Corpsof Engineers, Tech Memo 3-357, Vol 1-3).

67


Weathering and soil development Workability Slope stability and foundation conditions Dry density2 moisturecontent and UnifiedSoil Classification3

Remarks (includes use andearthquake stability)

Soil may be as much as 3ft thick.In places soil clayey, shrinks andswells; may cause damage tobuildings

Can be moved withhand or power tools

Depend on composition; gen¬

erally good. Slides have formedwhere colluvium apparently deriv¬edfrom gabbro

Varies Mapped with Temescal formation in Oak¬land West quadrangle(Radbruch, 1957)

Soil as much as 3 ft thick inplaces. Soil swells and shrinks withseasonal moisture changes andmay cause damage to buildings;may creep on slopes

Can be moved withhand tools

Weathering as much as 30 ft deep;highly weathered rock consists ofloose fragments in clay matrix.Soil generally lacking or less than18 in thick; in ravines may bemore than 12 ft thick

Depth of weathering irregular;may be 20 ft or more in places.Some weathered rock firm, mostsoft, clayey. Soil commonly 1-3 ftthick

Can generally be mov¬ed with power equip¬ment; in some placesrequires blasting

Can be moved withpower equipment

Large slides have formed in thisunit. Factors contributing to slideprobably include presence ofmontmorillonite clay and alter¬nating poorly consolidated sandand clay; steep slopes; andgroundwater. Generally suitablefoundation material for lightstructures where slopes are notsteep

Slope stability and foundationconditions good. Rare debrisslides observed where rock exces¬

sively fractured and weathered

Slope stability and foundationconditions generally fair; minorsloughing in cuts

1.68; 18 percent (77: 1.45-1.97; 8-30 percent) GM-CH

2.59 (s); 0.1 percent; 99(weathered);20 per cent(3:1.57-1.63;9-27 per cent)

2 56 (s)(ss);1.4 per cent;1.86 (weather¬ed sh); 15 percent (3: 1.81-1.92; 13-19 percent)

Crushed Leona rhyo¬lite is a major sourceof fill and base rock;pyrite formerly minedfor sulfur ; runoff fromrhyolite hills very acidand corrodes concretesewer pipe. Some slo¬

pes so steep that de¬

velopment may be dif¬ficult

May squeeze in tunnelswhere sheared

Text printed in italics indicates geologic conditions that may be critical to planning, design, and construction of engineering worksDry density (italic) expressed in tonnes per cu m, based on one sample of fresh rock unless otherwise noted Number of samples and range of dry density and moisture contentgiven in parentheses (12 169-1 74, 17-20 per cent) (s) indicates sample collected at the surface Moisture content (per cent) generally higher for subsurface samples of rocksthan for those collected at the surfaceUnified Soil Classification (letter symbol) given where applicable (United States Army, Corps of Engineers, 1953, The Unified Soil Classification System, United States Army, Corpsof Engineers, Tech Memo 3-357, Vol 1-3).

67


5.4.2 INTERPRETATIVE GEOLOGICAL LARGE-SCALE MAP

I." t 1 /,' / '* '* +

si*' ^ %'

+ '.¥T. *-^.'* +

ED

^v-< f.-

o

Rhyolitic tuff

Granite, fine-grained

Granite, coarse-grained

Zone of weathering grade V

Spoil tip

Quarry

Stream, with direction of flow

Spring

"TtTT Seepage line

^

Alluvium along stream

Mine shaft, abandoned

Slope on spoil tip

Solifluxion lobe

Inclined strata, dip in degrees,normal succession

Inclined strata, dip in degrees,inverted succession

Vertical strata

Joint, inclined, dip in degrees

Joint, vertical

Discontinuity pattern, statistical¬ly determined

Boundary of superficial deposit,certain

Boundary, solid, certain

Boundary, solid, approximate

" Axial trace of syncline

" Fault, approximate position

Trial trench

siii.porii27 gjjg investigation

Borehole

Borehole, inclined

68


Comment

The map, reproduced at a scale of 1 : 10,000, is an example ofa geological map and legend supplemented with additionaldescriptive information in engineering geological terms. It isbased on a part of a typical Institute of Geological Sciencesmap produced on a scale of 1 : 10,560; such geological mapsare available for over 85 per cent of the land area of theUnited Kingdom and are useful at the preliminary planningstage of an engineering undertaking; mechanically enlarged,they could form the basis of pre-construction or site investi¬gation maps. Supplementation was not undertaken officially.

This example has been slightly modified from 2.9.1. Partof a 1 : 10,560 map supplemented as proposed. Dearman etal. 'Working Party Report on the Preparation of Maps andPlans in Terms of Engineering Geology', Q.Jl Engng Geol,vol.5, 1972, p. 293-381.

Legend

SUPERFICIAL DEPOSITS (DRIFT). RECENT AND PLEISTOCENE

Alluvium. On the granite, alluvium is a Thicknessbrownish-yellow, loose, sub-angular, (in m)coarse gravelly sand with some peat androunded boulders of moderately weath- Up to 3

ered granite up to 1 m, and pebbles ofquartz. Downstream, alluvium is a siltygravelly sand with rounded graniteboulders up to 1 m and sub-angular cob¬bles and boulders of the solid rocks. Thedeposits are moderately to highly perme¬able. Locally much disturbed by stream¬ing for tin.

River terraces (undifferentiated). Dark Up to 12

yellowish-brown, loose but locally weak¬ly to strongly cemented in horizontallayers by manganiferous or ferruginousmaterial, sub-angular to rounded, sandygravel with rounded to sub-angular cob¬bles and boulders of local rocks. Bould¬ers occasionally up to 1 m. The depositsare highly permeable except wherecemented. Locally much disturbed bystreaming for tin.

Head. Almost everywhere present and 2-3,largely obscures the solid formations, locally >12Represents solifluxion debris and gradesdownslope into alluvium and terrace de¬

posits.Within the outcrop of the granite,

head comprises yellowish-brown, loose,layered, sandy gravel with some clay,and gravelly silty sand with cobbles andboulders of moderately weathered gra¬

nite; grades down into moderately tohighly weathered granite in situ. On theUpper Carboniferous outcrop next tothe granite, head is typically reddish-brown, loose to compact, homogeneous,clayey gravelly sand with many sub-angular cobbles; on steep slopes finesmay be absent and head is then loose,clean cobbles of the local rocks beneath15-30 cm of humic soil.

On the Lower Carboniferous rocks,head is reddish-brown, loose to com¬

pact, homogeneous silty clayey sandwith some cobbles and boulders of local

rocks; it may be layered with an upper Thicknessgrey horizon separated by a black (in m)cemented layer typically 8 cm thick fromreddish-brown head down to bedrock.

SOLID FORMATIONS. CARBONIFEROUS

Upper Carboniferous (Namurian)

CkFCrackington formation. Dark to verydark grey, very fine grained, thinlybedded to thinly laminated, very closelyjointed, slightly to moderately weath¬ered, poorly cleaved shale, weak, imper¬meable except along open joints. Inter¬bedded with very subordinate grey todark greenish grey fine-grained, verythinly bedded, thinly laminated andcross-laminated, closely, jointed, slightlyto moderately weathered siltstone, mod¬erately strong and dark greenish greymedium grained, very thinly ti> mediumbedded, with closely to widely spacedjoints slightly to moderately weathered,sandstone, strong.

The shale slakes on exposure and issuitable for brick making.

Sandstone. It has been possible to mapgroups of beds m which sandstone pre¬

dominates. Beds are usually less than30 cm thick and are separated by verythin beds of siltstone and shale.

Sandstones are suitable for aggre¬

gate production.Within the contact metamorphic

aureole of the granite, dark grey, verypale orange to dusky yellowish-brown,fine to medium grained, thinly bedded,closely jointed, slightly to moderatelyweathered, hornfelsed shale and sand¬

stone, strong, impervious except alongopen joints. Locally with fine grainedblack tourmaline developed as selvedgesup to 2.5 cm wide along discontinuitiesand with irregular quartz veins up to5 cm wide.

Lower Carboniferous (Dinantian)

I I Meldon chert formation 75

69


Comment

The map, reproduced at a scale of 1 : 10,000, is an example ofa geological map and legend supplemented with additionaldescriptive information in engineering geological terms. It isbased on a part of a typical Institute of Geological Sciencesmap produced on a scale of 1 : 10,560; such geological mapsare available for over 85 per cent of the land area of theUnited Kingdom and are useful at the preliminary planningstage of an engineering undertaking; mechanically enlarged,they could form the basis of pre-construction or site investi¬gation maps. Supplementation was not undertaken officially.

This example has been slightly modified from 2.9.1. Partof a 1 : 10,560 map supplemented as proposed. Dearman etal. 'Working Party Report on the Preparation of Maps andPlans in Terms of Engineering Geology', Q.Jl Engng Geol,vol.5, 1972, p. 293-381.

Legend

SUPERFICIAL DEPOSITS (DRIFT). RECENT AND PLEISTOCENE

Alluvium. On the granite, alluvium is a Thicknessbrownish-yellow, loose, sub-angular, (in m)coarse gravelly sand with some peat androunded boulders of moderately weath- Up to 3

ered granite up to 1 m, and pebbles ofquartz. Downstream, alluvium is a siltygravelly sand with rounded graniteboulders up to 1 m and sub-angular cob¬bles and boulders of the solid rocks. Thedeposits are moderately to highly perme¬able. Locally much disturbed by stream¬ing for tin.

River terraces (undifferentiated). Dark Up to 12

yellowish-brown, loose but locally weak¬ly to strongly cemented in horizontallayers by manganiferous or ferruginousmaterial, sub-angular to rounded, sandygravel with rounded to sub-angular cob¬bles and boulders of local rocks. Bould¬ers occasionally up to 1 m. The depositsare highly permeable except wherecemented. Locally much disturbed bystreaming for tin.

Head. Almost everywhere present and 2-3,largely obscures the solid formations, locally >12Represents solifluxion debris and gradesdownslope into alluvium and terrace de¬

posits.Within the outcrop of the granite,

head comprises yellowish-brown, loose,layered, sandy gravel with some clay,and gravelly silty sand with cobbles andboulders of moderately weathered gra¬

nite; grades down into moderately tohighly weathered granite in situ. On theUpper Carboniferous outcrop next tothe granite, head is typically reddish-brown, loose to compact, homogeneous,clayey gravelly sand with many sub-angular cobbles; on steep slopes finesmay be absent and head is then loose,clean cobbles of the local rocks beneath15-30 cm of humic soil.

On the Lower Carboniferous rocks,head is reddish-brown, loose to com¬

pact, homogeneous silty clayey sandwith some cobbles and boulders of local

rocks; it may be layered with an upper Thicknessgrey horizon separated by a black (in m)cemented layer typically 8 cm thick fromreddish-brown head down to bedrock.

SOLID FORMATIONS. CARBONIFEROUS

Upper Carboniferous (Namurian)

CkFCrackington formation. Dark to verydark grey, very fine grained, thinlybedded to thinly laminated, very closelyjointed, slightly to moderately weath¬ered, poorly cleaved shale, weak, imper¬meable except along open joints. Inter¬bedded with very subordinate grey todark greenish grey fine-grained, verythinly bedded, thinly laminated andcross-laminated, closely, jointed, slightlyto moderately weathered siltstone, mod¬erately strong and dark greenish greymedium grained, very thinly ti> mediumbedded, with closely to widely spacedjoints slightly to moderately weathered,sandstone, strong.

The shale slakes on exposure and issuitable for brick making.

Sandstone. It has been possible to mapgroups of beds m which sandstone pre¬

dominates. Beds are usually less than30 cm thick and are separated by verythin beds of siltstone and shale.

Sandstones are suitable for aggre¬

gate production.Within the contact metamorphic

aureole of the granite, dark grey, verypale orange to dusky yellowish-brown,fine to medium grained, thinly bedded,closely jointed, slightly to moderatelyweathered, hornfelsed shale and sand¬

stone, strong, impervious except alongopen joints. Locally with fine grainedblack tourmaline developed as selvedgesup to 2.5 cm wide along discontinuitiesand with irregular quartz veins up to5 cm wide.

Lower Carboniferous (Dinantian)

I I Meldon chert formation 75

69



70


Legend Comment

Opencast prospecting boreholes

Diamond, drill rock cores taken

1

1

c

o

©

e

o

o

^w

â

-^

12

Water flush chip samples

Hand auger in soil

Engineering site investigation boreholes

Shell and auger

Shell and auger with rotary core in rock

Shell and auger with rotary in rock

Rotary rock roller

Research boreholes

Power auger disturbed samples

Well, backfilled or inaccessible

Mine shaft, abandoned

Trial pitSewer trenchGeophysics constant separation resistivitytraverse

Area of site investigation, with referencenumber

A typical documentation map recording the location andnature of archival information from which engineering-geo¬logical and other maps of the area have been produced. Thecomplete map, with National Grid co-ordinates, is linked toa punched-card data retrieval system ; some of the data hasbeen experimentally coded for computer storage andretrieval.

Part of the documentation map at a scale of 1 : 10,000being prepared for the engineering-geological survey of theTyne and Wear Metropohtan County, northern England.The example presented here is from Dearman et al. 'Techni¬ques of Engineering-Geological Mapping with Examplesfrom Tyneside'. The Engineering Geology of Reclamation andRedevelopment Regional Meeting, Durham, EngineeringGroup, Geological Society, p. 31-4, 1973.

Í6oc J Opencast prospecting area, with referencej number

71

Layout of descriptive memoir 6

Ideally, a comprehensive engineering geological map shouldbe accompanied by a descriptive memoir containing the fol¬lowing information:

Contents

IntroductionPurpose of the engineering geological mapGeographical location of mapped area

Topographical dataRoad, rail and other transportation routesEconomic evaluation, and development prospects

Previous investigationsMethods used in the engineering-geological survey of thearea

Extent of the investigationsOrganizations which carried out the survey

Physical geographyClimatic factors influencing the evaluation of engineeringgeological conditionsPhysiographic descriptionHydrography

Geological structure and developmentPre-QuaternaryQuaternaryPresent geodynamic processes

Geological characteristics of rocks and soils and their en¬

gineering geological propertiesRocksSoils

Hydrogeological conditionsCharacteristics of individual aquifersGroundwater chemistry

Engineering-geological zoningPrinciples applied to the map areaCharacteristics of individual zoning units

Construction and other materials

Conclusions

Recommendations

AppendixesReferencesSources of archival and other materialTables of engineering geological properties

Index

The memoir would be illustrated by diagrams, graphs, tablesand photographs.

The content of the memoir would, of course, be relatedto the purpose, content and scale of the map, and the layoutof chapters given above is suggested as a basic guide fromwhich suitable chapter headings may be selected.

72

Layout of descriptive memoir 6

Ideally, a comprehensive engineering geological map shouldbe accompanied by a descriptive memoir containing the fol¬lowing information:

Contents

IntroductionPurpose of the engineering geological mapGeographical location of mapped area

Topographical dataRoad, rail and other transportation routesEconomic evaluation, and development prospects

Previous investigationsMethods used in the engineering-geological survey of thearea

Extent of the investigationsOrganizations which carried out the survey

Physical geographyClimatic factors influencing the evaluation of engineeringgeological conditionsPhysiographic descriptionHydrography

Geological structure and developmentPre-QuaternaryQuaternaryPresent geodynamic processes

Geological characteristics of rocks and soils and their en¬

gineering geological propertiesRocksSoils

Hydrogeological conditionsCharacteristics of individual aquifersGroundwater chemistry

Engineering-geological zoningPrinciples applied to the map areaCharacteristics of individual zoning units

Construction and other materials

Conclusions

Recommendations

AppendixesReferencesSources of archival and other materialTables of engineering geological properties

Index

The memoir would be illustrated by diagrams, graphs, tablesand photographs.

The content of the memoir would, of course, be relatedto the purpose, content and scale of the map, and the layoutof chapters given above is suggested as a basic guide fromwhich suitable chapter headings may be selected.

72

Glossary 7

7.1 IntroductionIn compiling this glossary, reference has been made to stan¬

dard geological dictionaries written in English (Anon., 1962;Challinor, 1967; Gary et al, 1972; Schieferdecker, 1959;Whitten and Brooks, 1972) and to the English version of thereport of the Commission on Terminology, Symbols andGraphic Representation (Anon., 1970) of the InternationalSociety for Rock Mechanics. Purely geological, as distinctfrom engineering geological, terms used in the text are notdefined if there is a satisfactory definition in either of twoinexpensive and readily available English dictionaries of geo¬

logical terms (Anon., 1962; Whitten and Brooks, 1972).References are also given (7.3.2) to geological diction¬

aries written in other languages.

7.2 Definitions of terms usedin the text

angle of internal friction Angle of shear resistance ; the an¬

gle (0) between the axis of normal stress and the tangentto the Mohr envelope at a point representing a givenfailure-stress condition for solid material.

archives The place in which government or public recordsare kept (adj. : archival).

area A taxonomic unit in engineering geological zoningdelimited on the basis of the uniformity of individualregional geomorphological units.

attribute A quality or property inherent in anything.attrition value See value, attrition.classification The formal arrangement into the groups of a

hierarchy of taxonomic categories.coefficient, permeability The rate of flow of water through

a unit cross-section under a unit hydraulic gradient.coefficient, storage The volume of water released from stor¬

age in each vertical column of the aquifer having a base ofunit area when the water table or other piezometric sur¬

face declines by one unit of depth.cohesion Shear resistance at zero normal stress.

compaction The packing together of soil particles with theexpulsion of air only. It is accomplished by rolling, ramm¬ing or vibration, and results in a decrease in the air voidsand an increase in the density of the soil.

component, engineering geological environment The basic

geological and geographical features which are of decisivesignificance for engineering geological mapping, namelythe distribution and properties of rocks and soils, ground¬water, characteristics of the relief, and present geodynamicprocesses.

compressibility The decrease in volume per unit increase ofpressure.

confined water See water, confined.consistency Cohesive soils may be classified as stiff, firm or

soft depending upon their consistency ; the terms are indi¬cative of the ease or difficulty with which the soil is exca¬

vated with a spade or moulded in the fingers. Consistencylimits are the moisture contents at which a soil passes fromthe liquid to the plastic to the solid state.

creep Time dependent deformation; the ability of rocksand other naturally occurring materials to be slowly, con¬

tinuously and permanently deformed under loads over along period of time.

deformability See deformation.deformation A change in shape or size of a solid body.density Bulk density; the weight of a material, including

the effect of voids whether filled with air or water, per unitvolume.

discontinuity An open, or potentially openable, structuralplane such as a bed, joint, cleavage, fault.

district A taxonomic unit in engineering geological zoningin which hydrogeological conditions and geodynamicphenomena are uniform.

durability Power of resisting decay; resistance of a rock toweakening and disintegration when subjected to shortterm weathering processes. Slake durability, resistance towetting and drying.

engineering geological component See component, en¬

gineering geological environment.engineering geological conditions The dynamic geological

system of the rocks and soils, water, geomorphologicalconditions and geodynamic processes at an individual siteor area.

engineering geological map See map, engineering geologi¬cal.

engineering geological type The mapping unit with thehighest degree of physical homogeneity. It should be uni¬form in lithological character and physical state.

fall Applied to mass movement (q.v.); downward and out¬

ward movement of slope-forming materials, in which themoving mass travels mostly through the air by free fall,

73

Glossary 7

7.1 IntroductionIn compiling this glossary, reference has been made to stan¬

dard geological dictionaries written in English (Anon., 1962;Challinor, 1967; Gary et al, 1972; Schieferdecker, 1959;Whitten and Brooks, 1972) and to the English version of thereport of the Commission on Terminology, Symbols andGraphic Representation (Anon., 1970) of the InternationalSociety for Rock Mechanics. Purely geological, as distinctfrom engineering geological, terms used in the text are notdefined if there is a satisfactory definition in either of twoinexpensive and readily available English dictionaries of geo¬

logical terms (Anon., 1962; Whitten and Brooks, 1972).References are also given (7.3.2) to geological diction¬

aries written in other languages.

7.2 Definitions of terms usedin the text

angle of internal friction Angle of shear resistance ; the an¬

gle (0) between the axis of normal stress and the tangentto the Mohr envelope at a point representing a givenfailure-stress condition for solid material.

archives The place in which government or public recordsare kept (adj. : archival).

area A taxonomic unit in engineering geological zoningdelimited on the basis of the uniformity of individualregional geomorphological units.

attribute A quality or property inherent in anything.attrition value See value, attrition.classification The formal arrangement into the groups of a

hierarchy of taxonomic categories.coefficient, permeability The rate of flow of water through

a unit cross-section under a unit hydraulic gradient.coefficient, storage The volume of water released from stor¬

age in each vertical column of the aquifer having a base ofunit area when the water table or other piezometric sur¬

face declines by one unit of depth.cohesion Shear resistance at zero normal stress.

compaction The packing together of soil particles with theexpulsion of air only. It is accomplished by rolling, ramm¬ing or vibration, and results in a decrease in the air voidsand an increase in the density of the soil.

component, engineering geological environment The basic

geological and geographical features which are of decisivesignificance for engineering geological mapping, namelythe distribution and properties of rocks and soils, ground¬water, characteristics of the relief, and present geodynamicprocesses.

compressibility The decrease in volume per unit increase ofpressure.

confined water See water, confined.consistency Cohesive soils may be classified as stiff, firm or

soft depending upon their consistency ; the terms are indi¬cative of the ease or difficulty with which the soil is exca¬

vated with a spade or moulded in the fingers. Consistencylimits are the moisture contents at which a soil passes fromthe liquid to the plastic to the solid state.

creep Time dependent deformation; the ability of rocksand other naturally occurring materials to be slowly, con¬

tinuously and permanently deformed under loads over along period of time.

deformability See deformation.deformation A change in shape or size of a solid body.density Bulk density; the weight of a material, including

the effect of voids whether filled with air or water, per unitvolume.

discontinuity An open, or potentially openable, structuralplane such as a bed, joint, cleavage, fault.

district A taxonomic unit in engineering geological zoningin which hydrogeological conditions and geodynamicphenomena are uniform.

durability Power of resisting decay; resistance of a rock toweakening and disintegration when subjected to shortterm weathering processes. Slake durability, resistance towetting and drying.

engineering geological component See component, en¬

gineering geological environment.engineering geological conditions The dynamic geological

system of the rocks and soils, water, geomorphologicalconditions and geodynamic processes at an individual siteor area.

engineering geological map See map, engineering geologi¬cal.

engineering geological type The mapping unit with thehighest degree of physical homogeneity. It should be uni¬form in lithological character and physical state.

fall Applied to mass movement (q.v.); downward and out¬

ward movement of slope-forming materials, in which themoving mass travels mostly through the air by free fall,

73


leaping, bounding or rolling, with little or no interactionbetween one moving unit and another.

flow Applied to mass movement (q.v.); downward and out¬ward movement of slope-forming materials, in which themovement within the displaced mass is such that the formtaken by the moving material, or the apparent distributionof velocities and displacements, resembles those of viscousfluids.

formation The fundamental formal unit of lithostratigraph¬ical (q.v.) classification; it is the only formal unit which isused for completely dividing the whole stratigraphicalcolumn all over the world into named units on the basis oflithostratigraphical character.

frost heave The lifting of a surface by the internal action offrost.

geodynamic Referring to those geological features of theenvironment resulting from geological processes active atthe present time.

geohydrology See hydrogeology.geomorphology That branch of both physiography and

geology which deals with the form of the earth, the generalconfiguration of its surface, and the changes that takeplace in the evolution of land forms.

geophysics Geophysical method ; geological exploration us¬

ing the instruments and applying the methods of physicsand engineering; exploration by observation of seismic orelectrical phenomena or of the earth's gravitational ormagnetic fields or thermal distribution.

groundwater Subsurface water in the zone of saturation inthe lithosphère.

group A stratigraphical sequence of two or more contig¬uous formations having significant unifying lithologicalfeatures in common.

homogeneity Having the same property throughout.hydrochemical Referring to the chemical composition of

natural waters.hydrogeology That part of hydrology which relates to the

water in the lithosphère.infiltration The flow or movement of water through the soil

surface into the ground.in situ In its natural position or place.in situ test See test, in situ.iso- Equal; a prefix, extensively used in conjunction with

another word, to denote lines drawn on a map throughpoints of equal value of the element displayed.

isobath A line joining points of equal depth ; for example, aline on a land surface all points of which are the samevertical distance above the upper or lower surface of anaquifer may be called an isobath of the specified surface.

isohypse Contour of groundwater level or watertable.isoline Equal line ; on an isoline map some variable feature

is contoured.isopachyte Isopach; isopachous line; a line, on a map,

drawn through points of equal thickness of a designatedunit.

isopiestic Isopiestic line; a contour of the piezometric sur¬

face of an aquifer.isoseism Isoseismic line; an imaginary line connecting all

points on the surface of the earth where an earthquakeshock is of the same intensity.

isotropic Having the same properties in all directions.landslide Landslip; a portion of a hillside or sloping mass

which has become loosened or detached and has slippeddown.

land-use Use of land by man.

legend A brief discription of the symbols and patternsshown on a map or diagram.

lithogenetic See lithogenesis.lithogenesis The origin and formation of rocks.lithological complex A mapping unit comprising a set of

genetically related lithological types.lithological suite A mapping unit comprising many litho¬

logical complexes which are paragenetically related.hthological type A mapping unit which is homogeneous

throughout in composition, texture and structure, butusually not uniform in physical state.

lithostratigraphy Stratigraphy based only on the physicaland pétrographie features of rocks (adj. : lithostratigraphi¬cal).

map A representation on a plane surface, at a specifiedscale, of the physical features of a part of the earth's sur¬

face or of any selected surface or subsurface data, bymeans of signs and symbols.

map, engineering geological A type of geological map pro¬viding a generalized representation of all the componentsof a geological environment of significance in land-useplanning, and in design, construction and maintenance as

applied to civil engineering.map, engineering geological, analytical A map evaluating

an individual component of the geological environment.map, engineering geological, auxiliary A map presenting

factual data, for example a documentation map.map, engineering geological, complementary A map of

basic geological and other non-engineering geologicaldata.

map, engineering geological, comprehensive A map of en¬

gineering geological conditions depicting all the principalcomponents of the engineering geological environment; ora map of engineering geological zoning.

map, engineering geological, multi-purpose A map provid¬ing information on many aspects of engineering geologyfor a variety of planning and engineering purposes.

map, engineering geological, special purpose A map pro¬viding information on one specific aspect of engineeringgeology, or for one specific purpose.

map, interpretative A general geological map interpreted inengineering geological terms.

map, large-scale A map drawn at a scale of 1 : 10,000 orgreater.

map, medium-scale A map drawn at a scale less than1 : 10,000 and greater than 1 : 100,000.

map, small-scale A map drawn at a scale of 1 : 100,000 orless.

mass movement (syn.: mass wasting) A general term forthe dislodgement and downslope transport of rock andsoil material under the direct application of gravitationalbody stresses.

mechanical property See physical property.modulus, deformation The ratio of stress to corresponding

strain during loading of a rock mass including elastic andinelastic behaviour.

permeability The capacity of a rock or soil to conduct(transmit) liquid or gas. It is measured as the proportion¬ality constant K between flow velocity v and hydraulicgradient /; v = kl. The unit of permeability is the darcy.

pH The negative logarithm of the hydrogen ion activity.photogrammetry The science of obtaining reliable measure¬

ments from photographs.physical property A characteristic of rock or soil ; a distinc¬

tion may be made between a mechanical property which

74


leaping, bounding or rolling, with little or no interactionbetween one moving unit and another.

flow Applied to mass movement (q.v.); downward and out¬ward movement of slope-forming materials, in which themovement within the displaced mass is such that the formtaken by the moving material, or the apparent distributionof velocities and displacements, resembles those of viscousfluids.

formation The fundamental formal unit of lithostratigraph¬ical (q.v.) classification; it is the only formal unit which isused for completely dividing the whole stratigraphicalcolumn all over the world into named units on the basis oflithostratigraphical character.

frost heave The lifting of a surface by the internal action offrost.

geodynamic Referring to those geological features of theenvironment resulting from geological processes active atthe present time.

geohydrology See hydrogeology.geomorphology That branch of both physiography and

geology which deals with the form of the earth, the generalconfiguration of its surface, and the changes that takeplace in the evolution of land forms.

geophysics Geophysical method ; geological exploration us¬

ing the instruments and applying the methods of physicsand engineering; exploration by observation of seismic orelectrical phenomena or of the earth's gravitational ormagnetic fields or thermal distribution.

groundwater Subsurface water in the zone of saturation inthe lithosphère.

group A stratigraphical sequence of two or more contig¬uous formations having significant unifying lithologicalfeatures in common.

homogeneity Having the same property throughout.hydrochemical Referring to the chemical composition of

natural waters.hydrogeology That part of hydrology which relates to the

water in the lithosphère.infiltration The flow or movement of water through the soil

surface into the ground.in situ In its natural position or place.in situ test See test, in situ.iso- Equal; a prefix, extensively used in conjunction with

another word, to denote lines drawn on a map throughpoints of equal value of the element displayed.

isobath A line joining points of equal depth ; for example, aline on a land surface all points of which are the samevertical distance above the upper or lower surface of anaquifer may be called an isobath of the specified surface.

isohypse Contour of groundwater level or watertable.isoline Equal line ; on an isoline map some variable feature

is contoured.isopachyte Isopach; isopachous line; a line, on a map,

drawn through points of equal thickness of a designatedunit.

isopiestic Isopiestic line; a contour of the piezometric sur¬

face of an aquifer.isoseism Isoseismic line; an imaginary line connecting all

points on the surface of the earth where an earthquakeshock is of the same intensity.

isotropic Having the same properties in all directions.landslide Landslip; a portion of a hillside or sloping mass

which has become loosened or detached and has slippeddown.

land-use Use of land by man.

legend A brief discription of the symbols and patternsshown on a map or diagram.

lithogenetic See lithogenesis.lithogenesis The origin and formation of rocks.lithological complex A mapping unit comprising a set of

genetically related lithological types.lithological suite A mapping unit comprising many litho¬

logical complexes which are paragenetically related.hthological type A mapping unit which is homogeneous

throughout in composition, texture and structure, butusually not uniform in physical state.

lithostratigraphy Stratigraphy based only on the physicaland pétrographie features of rocks (adj. : lithostratigraphi¬cal).

map A representation on a plane surface, at a specifiedscale, of the physical features of a part of the earth's sur¬

face or of any selected surface or subsurface data, bymeans of signs and symbols.

map, engineering geological A type of geological map pro¬viding a generalized representation of all the componentsof a geological environment of significance in land-useplanning, and in design, construction and maintenance as

applied to civil engineering.map, engineering geological, analytical A map evaluating

an individual component of the geological environment.map, engineering geological, auxiliary A map presenting

factual data, for example a documentation map.map, engineering geological, complementary A map of

basic geological and other non-engineering geologicaldata.

map, engineering geological, comprehensive A map of en¬

gineering geological conditions depicting all the principalcomponents of the engineering geological environment; ora map of engineering geological zoning.

map, engineering geological, multi-purpose A map provid¬ing information on many aspects of engineering geologyfor a variety of planning and engineering purposes.

map, engineering geological, special purpose A map pro¬viding information on one specific aspect of engineeringgeology, or for one specific purpose.

map, interpretative A general geological map interpreted inengineering geological terms.

map, large-scale A map drawn at a scale of 1 : 10,000 orgreater.

map, medium-scale A map drawn at a scale less than1 : 10,000 and greater than 1 : 100,000.

map, small-scale A map drawn at a scale of 1 : 100,000 orless.

mass movement (syn.: mass wasting) A general term forthe dislodgement and downslope transport of rock andsoil material under the direct application of gravitationalbody stresses.

mechanical property See physical property.modulus, deformation The ratio of stress to corresponding

strain during loading of a rock mass including elastic andinelastic behaviour.

permeability The capacity of a rock or soil to conduct(transmit) liquid or gas. It is measured as the proportion¬ality constant K between flow velocity v and hydraulicgradient /; v = kl. The unit of permeability is the darcy.

pH The negative logarithm of the hydrogen ion activity.photogrammetry The science of obtaining reliable measure¬

ments from photographs.physical property A characteristic of rock or soil ; a distinc¬

tion may be made between a mechanical property which

74

Glossary

can be determined by a machine, e.g. uniaxial compressivestrength, and a physical property which can be determinedby the senses.

piezometric Piezometric surface; an imaginary surface thateverywhere coincides with the static level of the water inan aquifer; the surface to which the water from a givenaquifer will rise under its full head.

point symbol See symbol, point.pressure Force per unit area applied to the outside of a

body.pressure, uplift The hydrostatic force of water exerted on

or underneath a structure tending to cause a displacementof the structure.

region A taxonomic unit in engineering geological zoningbased on the uniformity of individual geotectonic struc¬tural elements.

resistivity method A geophysical method of investigation inwhich the mean resistivity of the ground is measured andanalysed.

rock Strictly, any naturally formed aggregate or mass ofmineral matter, whether or not coherent, constituting anessential and appreciable part of the earth's crust. In theengineering sense, hard, solid, and rigid deposits formingparts of the earth's crust. There are some naturally occur¬ring materials which have properties intermediate betweenthose of rocks and soils as defined here; they may bereferred to as semi-solid rocks or soft rocks. See also: soil.

rock mass Rock as it occurs in situ, including structuraldiscontinuities and the effects of weathering.

rock material Rock in the hand-specimen, generally exclud¬ing the structural discontinuities of the rock mass; rockmaterial may be weathered and may contain micro-discon¬tinuities, for instance incipient joints.

salinity A measure of the quantity of total dissolved solidsin water.

sample A representative unit of a rock or soil material ormass.

sample, disturbed A rock or soil sample which does notretain the characteristics of the in situ material.

sample, undisturbed A rock or sou sample which retains,to a high degree, the characteristics of the in situ material.

seepage The infiltration or percolation of water throughrock or soil to or from the surface. The term seepage isusually restricted to the very slow movement of ground¬water.

seepage force The frictional drag of water flowing throughvoids or interstices in rock or soil causing an increase inthe intergranular pressure, i.e. the hydraulic force per unitvolume of rock or soil which results from the flow ofwater and which acts in the direction of flow.

seismic method A geophysical method of investigation inwhich the travel times of refracted and reflected elasticwaves through the ground are measured and analysed.

slide The descent of a mass of soil or rock down a hill ormountain side.

slope movement Mass movement on an inclined topo¬graphic surface.

soil An aggregate of mineral grains that can be separatedby such gentle means as agitation in water. The mineralgrains may be uncemented or very weakly cemented as insands and gravels, or may be bound together by weakforces, such as Van de Vaal's forces, as in silts and clays.

spring, suffusion A natural upwelling of water carryingwith it fine particles from unconsolidated materials. Seealso: suffosion.

storage coefficient See coefficient, storage.strength Maximum stress which a material can resist

without failing for any given type of loading.strength, compressive Maximum stress which a material

can resist without failing in compression.strength, shear Maximum stress which a material can resist

without failing by shear.strength, tensile Maximum stress which a material can

resist without failing in tension.structure (petrology) The larger-scale interrelationships of

textural features, generally seen or studied best in the out¬crop rather than in hand specimen or thin section. Struc¬ture represents a discontinuity or major inhomogeneity,one of the larger morphological features of a rock mass(q.v.) such as jointing, bedding, cleavage, foliation. Notsynonymous with texture (q.v.).

structure (structural geology) The general disposition, atti¬tude, arrangement or relative positions of rock masses of aregion or area; the sum total of the structural features of anarea, consequent upon such deformational processes as

faulting, folding and igneous intrusion.subsidence Movement in which surface material is dis¬

placed vertically downwards with little or no horizontalcomponent.

suffosion misnomer for suffusion (q.v.).suffusion The washing out of fine particles from unconsoli¬

dated materials, in particular sands and gravels.suffusion spring See spring, suffusion.surficial, superficial Characteristic of, pertaining to, formed

on, situated at, or occurring on the earth's surface; espe¬

cially, consisting of unconsolidated residual, alluvial, orglacial deposits lying on the bedrock.

symbol, point A generalized indication of the nature andlocation of a natural phenomenon.

water table The plane which forms the upper surface of thezone of groundwater saturation.

taxonomy The laws and principles of orderly classification(adj.: taxonomic).

terrain, terrane The tract or region of ground immediatelyunder observation.

test, in situ A geotechnical test carried out in an excavationor borehole in which the rock or soil under test is in itsnatural position and state.

texture The general physical appearance or character of a

rock including the geometrical aspects of, and the mutualrelations among, the component particles or crystals; e.g.the size, shape and arrangement of the constituent ele¬

ments of a sedimentary rock, or the crystallinity, granular¬ity and fabric of the constituent elements in an igneousrock.

uplift pressure See pressure, uplift.urbanization A conversion of land to a city and its asso¬

ciated industrial and recreational facilities.value, attrition A value, obtained under standardized test

conditions, of the resistance to wear of an aggregate stonesample.

water, confined Groundwater that is under sufficient pres¬

sure to rise above the level at which it is encountered by a

well or borehole.water content Moisture content ; the percentage by weight of

water contained in the pore space of a rock or soil withrespect to the weight of the solid material.

water table Groundwater surface, groundwater level; thelevel below which the rock and subsoil, to unknowndepths, are saturated.

75

Glossary

can be determined by a machine, e.g. uniaxial compressivestrength, and a physical property which can be determinedby the senses.

piezometric Piezometric surface; an imaginary surface thateverywhere coincides with the static level of the water inan aquifer; the surface to which the water from a givenaquifer will rise under its full head.

point symbol See symbol, point.pressure Force per unit area applied to the outside of a

body.pressure, uplift The hydrostatic force of water exerted on

or underneath a structure tending to cause a displacementof the structure.

region A taxonomic unit in engineering geological zoningbased on the uniformity of individual geotectonic struc¬tural elements.

resistivity method A geophysical method of investigation inwhich the mean resistivity of the ground is measured andanalysed.

rock Strictly, any naturally formed aggregate or mass ofmineral matter, whether or not coherent, constituting anessential and appreciable part of the earth's crust. In theengineering sense, hard, solid, and rigid deposits formingparts of the earth's crust. There are some naturally occur¬ring materials which have properties intermediate betweenthose of rocks and soils as defined here; they may bereferred to as semi-solid rocks or soft rocks. See also: soil.

rock mass Rock as it occurs in situ, including structuraldiscontinuities and the effects of weathering.

rock material Rock in the hand-specimen, generally exclud¬ing the structural discontinuities of the rock mass; rockmaterial may be weathered and may contain micro-discon¬tinuities, for instance incipient joints.

salinity A measure of the quantity of total dissolved solidsin water.

sample A representative unit of a rock or soil material ormass.

sample, disturbed A rock or soil sample which does notretain the characteristics of the in situ material.

sample, undisturbed A rock or sou sample which retains,to a high degree, the characteristics of the in situ material.

seepage The infiltration or percolation of water throughrock or soil to or from the surface. The term seepage isusually restricted to the very slow movement of ground¬water.

seepage force The frictional drag of water flowing throughvoids or interstices in rock or soil causing an increase inthe intergranular pressure, i.e. the hydraulic force per unitvolume of rock or soil which results from the flow ofwater and which acts in the direction of flow.

seismic method A geophysical method of investigation inwhich the travel times of refracted and reflected elasticwaves through the ground are measured and analysed.

slide The descent of a mass of soil or rock down a hill ormountain side.

slope movement Mass movement on an inclined topo¬graphic surface.

soil An aggregate of mineral grains that can be separatedby such gentle means as agitation in water. The mineralgrains may be uncemented or very weakly cemented as insands and gravels, or may be bound together by weakforces, such as Van de Vaal's forces, as in silts and clays.

spring, suffusion A natural upwelling of water carryingwith it fine particles from unconsolidated materials. Seealso: suffosion.

storage coefficient See coefficient, storage.strength Maximum stress which a material can resist

without failing for any given type of loading.strength, compressive Maximum stress which a material

can resist without failing in compression.strength, shear Maximum stress which a material can resist

without failing by shear.strength, tensile Maximum stress which a material can

resist without failing in tension.structure (petrology) The larger-scale interrelationships of

textural features, generally seen or studied best in the out¬crop rather than in hand specimen or thin section. Struc¬ture represents a discontinuity or major inhomogeneity,one of the larger morphological features of a rock mass(q.v.) such as jointing, bedding, cleavage, foliation. Notsynonymous with texture (q.v.).

structure (structural geology) The general disposition, atti¬tude, arrangement or relative positions of rock masses of aregion or area; the sum total of the structural features of anarea, consequent upon such deformational processes as

faulting, folding and igneous intrusion.subsidence Movement in which surface material is dis¬

placed vertically downwards with little or no horizontalcomponent.

suffosion misnomer for suffusion (q.v.).suffusion The washing out of fine particles from unconsoli¬

dated materials, in particular sands and gravels.suffusion spring See spring, suffusion.surficial, superficial Characteristic of, pertaining to, formed

on, situated at, or occurring on the earth's surface; espe¬

cially, consisting of unconsolidated residual, alluvial, orglacial deposits lying on the bedrock.

symbol, point A generalized indication of the nature andlocation of a natural phenomenon.

water table The plane which forms the upper surface of thezone of groundwater saturation.

taxonomy The laws and principles of orderly classification(adj.: taxonomic).

terrain, terrane The tract or region of ground immediatelyunder observation.

test, in situ A geotechnical test carried out in an excavationor borehole in which the rock or soil under test is in itsnatural position and state.

texture The general physical appearance or character of a

rock including the geometrical aspects of, and the mutualrelations among, the component particles or crystals; e.g.the size, shape and arrangement of the constituent ele¬

ments of a sedimentary rock, or the crystallinity, granular¬ity and fabric of the constituent elements in an igneousrock.

uplift pressure See pressure, uplift.urbanization A conversion of land to a city and its asso¬

ciated industrial and recreational facilities.value, attrition A value, obtained under standardized test

conditions, of the resistance to wear of an aggregate stonesample.

water, confined Groundwater that is under sufficient pres¬

sure to rise above the level at which it is encountered by a

well or borehole.water content Moisture content ; the percentage by weight of

water contained in the pore space of a rock or soil withrespect to the weight of the solid material.

water table Groundwater surface, groundwater level; thelevel below which the rock and subsoil, to unknowndepths, are saturated.

75


weathering That process of alteration of rocks and soilsoccurring under the direct influence of the hydrosphereand atmosphere.

zone A taxonomic unit in engineering geological zoning;based on lithological homogeneity and the structural ar¬

rangement of lithofacial complexes of rocks and soils.

7.3 References

Anon. 1962. Dictionary of geological terms. 2nd ed. New York,Dolphin Books.

Anon. 1970. Terminology, symbols and graphic representation.Commission of International Society of Rock Mechanics. 32 p.(Mimeo.)

Baulig H. 1956. Vocabulaire franco-anglo-allemand de géomorpho¬logie. Paris, Les Belles Lettres.

Challinor, J. 1967. A dictionary of geology. 3rd ed. Cardiff,University of Wales Press.

Comecon. 1968. (Terminological glossary on engineering geology.)Moscow. 2 vols. 400 and 226 p. (In Russian with glossary termsin eight languages including English.)

Gary, M.; McAfee Jr. R.; Wolf, C. L. (eds). 1972. Glossary ofgeology. Washington, D.C., American Geological Institute.

MaUaveev, A. A. 1971. (Glossary on hydrogeology and engineer¬

ing geology.) Moskva, Nedra. (In Russian.)Plaisance, G.; Cailleux, A. 1958. Dictionnaire des sols. Paris, La

Maison Rustique.Schieferdecker, A. A. G. 1959. Geological nomenclature. Royal

Geological and Mining Society of the Netherlands.Visser, A. D. 1965. Dictionary of soil mechanics in four languages:

English!American, French, Dutch and German. Amsterdam, Else¬

vier; Paris, Dunod.Whitten, D. G. A. ; Brooks, J. R. V. 1972. The Penguin dictionary

of geology. Harmondsworth, Penguin Books Ltd. (Penguin ref¬

erence books.)

76


weathering That process of alteration of rocks and soilsoccurring under the direct influence of the hydrosphereand atmosphere.

zone A taxonomic unit in engineering geological zoning;based on lithological homogeneity and the structural ar¬

rangement of lithofacial complexes of rocks and soils.

7.3 References

Anon. 1962. Dictionary of geological terms. 2nd ed. New York,Dolphin Books.

Anon. 1970. Terminology, symbols and graphic representation.Commission of International Society of Rock Mechanics. 32 p.(Mimeo.)

Baulig H. 1956. Vocabulaire franco-anglo-allemand de géomorpho¬logie. Paris, Les Belles Lettres.

Challinor, J. 1967. A dictionary of geology. 3rd ed. Cardiff,University of Wales Press.

Comecon. 1968. (Terminological glossary on engineering geology.)Moscow. 2 vols. 400 and 226 p. (In Russian with glossary termsin eight languages including English.)

Gary, M.; McAfee Jr. R.; Wolf, C. L. (eds). 1972. Glossary ofgeology. Washington, D.C., American Geological Institute.

MaUaveev, A. A. 1971. (Glossary on hydrogeology and engineer¬

ing geology.) Moskva, Nedra. (In Russian.)Plaisance, G.; Cailleux, A. 1958. Dictionnaire des sols. Paris, La

Maison Rustique.Schieferdecker, A. A. G. 1959. Geological nomenclature. Royal

Geological and Mining Society of the Netherlands.Visser, A. D. 1965. Dictionary of soil mechanics in four languages:

English!American, French, Dutch and German. Amsterdam, Else¬

vier; Paris, Dunod.Whitten, D. G. A. ; Brooks, J. R. V. 1972. The Penguin dictionary

of geology. Harmondsworth, Penguin Books Ltd. (Penguin ref¬

erence books.)

76


8.1 IntroductionThe bibliography sets out a selection of papers on engineering-geological maps and mapping and some examples of publishedengineering geological maps. Some of the papers contain examplesof engineering-geological maps, but neither these nor the pub¬lished maps follow the recommendations set out in this guidebookin their entirety.

8.2 Engineering geologicalmapping

Arnould, M.; Vantroys, M. 1970. Essai de cartographie géo¬

technique automatique sur la ville nouvelle d'Evry (Région pari¬sienne). International Association of Engineering Geology. FirstInternational Congress, vol. 2, p. 1069-80.

Bachmann, G.; Grô'we, H.; Helmerich, K.; Reuter, F.;Thomas, A. 1967. Instruktion für die Anfertigung einheitlicheringenieurgeologischer Grundkarten. Zentr. Geol. Inst. Abb.,vol. 9.

Blanc, R. P.; Cleveland, G. B. 1968. Natural slope stability as

related to geology, San Clémente area, Orange and San Diegocounties, California. 19 p. (Calif. Div. Mines and Geology specialreport, 98.)

Breddin, H.; Voight, R. 1967. Eine Baugrundplanungskarte fürLandkreis Kempen-Krefeld/Niederrhein [A building groundplanning map for the district Kempen-Krefeld/Niederrhein].Geologische Mitteilungen, vol. 7, p. 239-50.

Burton, A. N. 1970. The influence of tectonics on the geotechni-cal properties of Calabrian rocks and the mapping of slopeinstability using aerial photographs. Q. J. Engng Geol., vol. 2,

p. 237-54.Churinov, M. V., Tsypina, I. M.; Lazareva, V. P. 1962. Princi¬

ples and methods of compilation of universal areal maps of theU.S.S.R. at scales 1: 1,500,000 to 1: 2,500,000. Soviet Geology,no. 11, p. 112-24. (In Russian.). 1970. The principles of compiling the engineering-geologicalmap of the U.S.S.R. territory on the scale of 1:2,500,000. Inter¬national Association of Engineering Geology. First InternationalCongress, vol. 2, p. 850-60.

Dagneux, J. P.; Lemoine, Y. 1970. Cartographie géotechnique enmilieu côtier vaseux par sismique réfraction et pénétromètre.International Association of Engineering Geology. First Interna¬tional Congress, vol. 2, p. 895-903.

Dearman, W. R. et al. 1972. The preparation of maps and plansin terms of engineering geology. Q. J. Engng Geol., vol. 5,

p. 293-381.Dearman, W. R., Money, M. S.; Coffey, J. R.; Scott,

P.; Wheeler, M. 1973. Techniques of engineering-geological

mapping with examples from Tyneside. The engineering geologyof reclamation and redevelopment Regional Meeting, Durham,Engineering Group, Geological Society, p. 31-4.

Fookes, P. G. 1969. Geotechnical mapping of soils and sedimen¬tary rocks for engineering purposes with examples of practicefrom the Mangla Dam project. Géotechnique, vol. 19, p. 52-74.

Gazel, J.; Peter, A. 1969. Essais de cartographie géotechnique.Annales des Mines, Dec., p. 41-60.

Golodovskaya, G. A.; Demidyuk; L. M. 1970. The problem ofthe engineering and geological mapping of deposits of mineralresources in the area of eternal frost. International Association ofEngineering Geology. First International Congress, vol. 2,p. 1049-68.

Grabau, W. E. 1968. An integrated system for exploiting quanti¬tative terrain data for engineering purposes. In: G. A. Stewart(ed.), Land evaluation. CSIRO Symposium, p. 211-20. Canberra,Australia, Macmillan.

Grant, K. 1968a. A terrain evaluation system for engineering.Commonwealth Sei. Indus. Research Organization Australia, Div.Soil Mech., Tech. Paper 2, p. 27.. 1968ft. Terrain classification for engineering purposes of theRolling Downs Province. Commonwealth Sei. Indus. ResearchOrganization Australia, Div. Soil Mech., Tech. Paper 3, p. 385.

Humbert, M. et al., 1971. Mémoire explicatif de la carte géotech¬nique du Tanger au 1 : 25000. Contribution à la connaissancedu Tangérois. Notes et M. Serv. géol. Maroc, vol. 222, p. 190.

Janjic, M. 1962. Engineering-geological maps. Vesnik Zavod zaGeoloska i Geofizicka Istrazivanja (Bull. Inst. Geophys. Res),ser. B, no. 2, p. 17-31.

Lozinska-Stepien, H.; Stocklak, J. 1970. Metodyka sporzadza-nia map ingyniersko-geologiscznych w skali 1 : 5000 i wiekszych[Mapping methods for geological engineering 1 : 5000 and largerscale maps], Geological and engineering investigation in Poland,vol. 5, lnstytut Geologiczny Bull., vol. 231, p. 75-112. (In Polishwith English and Russian summaries.)

Lung, R., Proctor, R. (eds.). 1966. Engineering geology in sou¬

thern California. 389 p. (Assoc. Engineering Geologists LosAngeles Section special pub.)

Matula, M. 1969. Regional engineering geology of CzechoslovakCarpathians. Bratislava, Publishing House Slovak Academy ofSciences..1971. Engineering geologic mapping and evaluation in urbanplanning. In : D. R. Nichols and C. C. Campbell (eds.), Environ¬mental planning and geology, p. 144-53. (Geological Survey,United States Dept. of the Interior and the Office of Researchand Technology, United States Dept. of Housing and UrbanDevelopment.)

Nichols, D. R.; Campbell, C. C. (eds.). 1971. Environmental plan¬ning and geology. 204 p. (Geological Survey, United StatesDept. of the Interior and the Office of Research and Technolo¬gy, United States Dept. of Housing and Urban Development.)

77


8.1 IntroductionThe bibliography sets out a selection of papers on engineering-geological maps and mapping and some examples of publishedengineering geological maps. Some of the papers contain examplesof engineering-geological maps, but neither these nor the pub¬lished maps follow the recommendations set out in this guidebookin their entirety.

8.2 Engineering geologicalmapping

Arnould, M.; Vantroys, M. 1970. Essai de cartographie géo¬

technique automatique sur la ville nouvelle d'Evry (Région pari¬sienne). International Association of Engineering Geology. FirstInternational Congress, vol. 2, p. 1069-80.

Bachmann, G.; Grô'we, H.; Helmerich, K.; Reuter, F.;Thomas, A. 1967. Instruktion für die Anfertigung einheitlicheringenieurgeologischer Grundkarten. Zentr. Geol. Inst. Abb.,vol. 9.

Blanc, R. P.; Cleveland, G. B. 1968. Natural slope stability as

related to geology, San Clémente area, Orange and San Diegocounties, California. 19 p. (Calif. Div. Mines and Geology specialreport, 98.)

Breddin, H.; Voight, R. 1967. Eine Baugrundplanungskarte fürLandkreis Kempen-Krefeld/Niederrhein [A building groundplanning map for the district Kempen-Krefeld/Niederrhein].Geologische Mitteilungen, vol. 7, p. 239-50.

Burton, A. N. 1970. The influence of tectonics on the geotechni-cal properties of Calabrian rocks and the mapping of slopeinstability using aerial photographs. Q. J. Engng Geol., vol. 2,

p. 237-54.Churinov, M. V., Tsypina, I. M.; Lazareva, V. P. 1962. Princi¬

ples and methods of compilation of universal areal maps of theU.S.S.R. at scales 1: 1,500,000 to 1: 2,500,000. Soviet Geology,no. 11, p. 112-24. (In Russian.). 1970. The principles of compiling the engineering-geologicalmap of the U.S.S.R. territory on the scale of 1:2,500,000. Inter¬national Association of Engineering Geology. First InternationalCongress, vol. 2, p. 850-60.

Dagneux, J. P.; Lemoine, Y. 1970. Cartographie géotechnique enmilieu côtier vaseux par sismique réfraction et pénétromètre.International Association of Engineering Geology. First Interna¬tional Congress, vol. 2, p. 895-903.

Dearman, W. R. et al. 1972. The preparation of maps and plansin terms of engineering geology. Q. J. Engng Geol., vol. 5,

p. 293-381.Dearman, W. R., Money, M. S.; Coffey, J. R.; Scott,

P.; Wheeler, M. 1973. Techniques of engineering-geological

mapping with examples from Tyneside. The engineering geologyof reclamation and redevelopment Regional Meeting, Durham,Engineering Group, Geological Society, p. 31-4.

Fookes, P. G. 1969. Geotechnical mapping of soils and sedimen¬tary rocks for engineering purposes with examples of practicefrom the Mangla Dam project. Géotechnique, vol. 19, p. 52-74.

Gazel, J.; Peter, A. 1969. Essais de cartographie géotechnique.Annales des Mines, Dec., p. 41-60.

Golodovskaya, G. A.; Demidyuk; L. M. 1970. The problem ofthe engineering and geological mapping of deposits of mineralresources in the area of eternal frost. International Association ofEngineering Geology. First International Congress, vol. 2,p. 1049-68.

Grabau, W. E. 1968. An integrated system for exploiting quanti¬tative terrain data for engineering purposes. In: G. A. Stewart(ed.), Land evaluation. CSIRO Symposium, p. 211-20. Canberra,Australia, Macmillan.

Grant, K. 1968a. A terrain evaluation system for engineering.Commonwealth Sei. Indus. Research Organization Australia, Div.Soil Mech., Tech. Paper 2, p. 27.. 1968ft. Terrain classification for engineering purposes of theRolling Downs Province. Commonwealth Sei. Indus. ResearchOrganization Australia, Div. Soil Mech., Tech. Paper 3, p. 385.

Humbert, M. et al., 1971. Mémoire explicatif de la carte géotech¬nique du Tanger au 1 : 25000. Contribution à la connaissancedu Tangérois. Notes et M. Serv. géol. Maroc, vol. 222, p. 190.

Janjic, M. 1962. Engineering-geological maps. Vesnik Zavod zaGeoloska i Geofizicka Istrazivanja (Bull. Inst. Geophys. Res),ser. B, no. 2, p. 17-31.

Lozinska-Stepien, H.; Stocklak, J. 1970. Metodyka sporzadza-nia map ingyniersko-geologiscznych w skali 1 : 5000 i wiekszych[Mapping methods for geological engineering 1 : 5000 and largerscale maps], Geological and engineering investigation in Poland,vol. 5, lnstytut Geologiczny Bull., vol. 231, p. 75-112. (In Polishwith English and Russian summaries.)

Lung, R., Proctor, R. (eds.). 1966. Engineering geology in sou¬

thern California. 389 p. (Assoc. Engineering Geologists LosAngeles Section special pub.)

Matula, M. 1969. Regional engineering geology of CzechoslovakCarpathians. Bratislava, Publishing House Slovak Academy ofSciences..1971. Engineering geologic mapping and evaluation in urbanplanning. In : D. R. Nichols and C. C. Campbell (eds.), Environ¬mental planning and geology, p. 144-53. (Geological Survey,United States Dept. of the Interior and the Office of Researchand Technology, United States Dept. of Housing and UrbanDevelopment.)

Nichols, D. R.; Campbell, C. C. (eds.). 1971. Environmental plan¬ning and geology. 204 p. (Geological Survey, United StatesDept. of the Interior and the Office of Research and Technolo¬gy, United States Dept. of Housing and Urban Development.)

77


NiLSEN, T.H. 1971. Preliminary photointerpretation map of land¬

slide and other surficial deposits of the Mount Diablo Area, ContraCosta and Alamenda Counties, California. (United States Geol.Survey Miscellaneous Field Studies Map MF-310.)

Popov, I. V.; Kats, R. S.; Korikovskaia, A. K.; Lazareva, V. P.

1950. Metodika sostavlenia inzhenerno-geologischesikh kart [Thetechniques of compiling engineering geological maps]. Moskva,Gosgeohzdat.

Sanejouand, R. 1972. La cartographie géotechnique en France.Ministère de l'Equipement et du Logement, p. 96.

8.3 Published engineeringgeological maps

Brabb, E. E.; Pampeyan, E. H.; Bonilla, M. G. 1972. Landslidesusceptibility in San Mateo County, California. (United StatesGeol. Survey Miscellaneous Field Studies Map MF-310.)

Brown Jr., R. D. 1972. Active faults, probable active faults andassociatedfracture zones, San Mateo County, California (UnitedStates Geol. Survey Miscellaneous Field Studies Map MF-355.)

Bryant, B. 1972. Folio of the Aspen Quadrangle, Colorado.(United States Geol. Survey Miscellaneous Geologic Investiga¬tions Map I-785-A through G.)

Christiansen, E. A. (ed.) 1970. Physical environment of Saskatoon,Canada, p. 68. (Saskatchewan Research Council, Nat. ResearchCouncil Canada Pub. 1 1378.)

Debaille, G.; Ghiste, S. 1969. Carte géotechnique de la région deMons. Mons, Institut Reine Astrid. 44 p., 4 maps.

Fisher, W. L.; McGowen, J. H.; Brown Jr. L. F.; Groat, C. G.1972. Environmental geologic atlas of the Texas Coastal Zone-Galveston-Houston Area. Bureau of Economic Geology, TheUniversity of Texas at Austin. 91 p.

FÜLÓP, J. (ed.). 1969. Engineering-geological map series (scale 1:10,000) of the environs of Lake Balaton. Tihany, Budapest, Hun¬garian Geological Institute.

Radbruch, D. H. 1969. Areal and engineering geology of the Oak¬land East Quadrangle. (United States Geol. Survey Geol. Quad,Map GQ-769.)

Ronai, A. 1969. The geological atlas of the Great Hungarian Plain.Scale 1: 100,000. Budapest, Hungarian Geological Institute.

United States Geological Survey. 1967. Engineering geology ofthe North-east Corridor, Washington D.C., to Boston, Massa¬chusetts. (United States Geol. Survey Miscellaneous GeologicInvestigations Map I-514-A through C (scale 1 : 250,000).

Williams, P. L. et al. 1971-73. Folio of the Salina Quadrangle,Utah. (United States Geol. Survey Miscellaneous Geologic In¬vestigations Map I-591-A through N.)

78


NiLSEN, T.H. 1971. Preliminary photointerpretation map of land¬

slide and other surficial deposits of the Mount Diablo Area, ContraCosta and Alamenda Counties, California. (United States Geol.Survey Miscellaneous Field Studies Map MF-310.)

Popov, I. V.; Kats, R. S.; Korikovskaia, A. K.; Lazareva, V. P.

1950. Metodika sostavlenia inzhenerno-geologischesikh kart [Thetechniques of compiling engineering geological maps]. Moskva,Gosgeohzdat.

Sanejouand, R. 1972. La cartographie géotechnique en France.Ministère de l'Equipement et du Logement, p. 96.

8.3 Published engineeringgeological maps

Brabb, E. E.; Pampeyan, E. H.; Bonilla, M. G. 1972. Landslidesusceptibility in San Mateo County, California. (United StatesGeol. Survey Miscellaneous Field Studies Map MF-310.)

Brown Jr., R. D. 1972. Active faults, probable active faults andassociatedfracture zones, San Mateo County, California (UnitedStates Geol. Survey Miscellaneous Field Studies Map MF-355.)

Bryant, B. 1972. Folio of the Aspen Quadrangle, Colorado.(United States Geol. Survey Miscellaneous Geologic Investiga¬tions Map I-785-A through G.)

Christiansen, E. A. (ed.) 1970. Physical environment of Saskatoon,Canada, p. 68. (Saskatchewan Research Council, Nat. ResearchCouncil Canada Pub. 1 1378.)

Debaille, G.; Ghiste, S. 1969. Carte géotechnique de la région deMons. Mons, Institut Reine Astrid. 44 p., 4 maps.

Fisher, W. L.; McGowen, J. H.; Brown Jr. L. F.; Groat, C. G.1972. Environmental geologic atlas of the Texas Coastal Zone-Galveston-Houston Area. Bureau of Economic Geology, TheUniversity of Texas at Austin. 91 p.

FÜLÓP, J. (ed.). 1969. Engineering-geological map series (scale 1:10,000) of the environs of Lake Balaton. Tihany, Budapest, Hun¬garian Geological Institute.

Radbruch, D. H. 1969. Areal and engineering geology of the Oak¬land East Quadrangle. (United States Geol. Survey Geol. Quad,Map GQ-769.)

Ronai, A. 1969. The geological atlas of the Great Hungarian Plain.Scale 1: 100,000. Budapest, Hungarian Geological Institute.

United States Geological Survey. 1967. Engineering geology ofthe North-east Corridor, Washington D.C., to Boston, Massa¬chusetts. (United States Geol. Survey Miscellaneous GeologicInvestigations Map I-514-A through C (scale 1 : 250,000).

Williams, P. L. et al. 1971-73. Folio of the Salina Quadrangle,Utah. (United States Geol. Survey Miscellaneous Geologic In¬vestigations Map I-591-A through N.)

78

Acknowledgements 9

Members of the commission would wish to record their in¬

debtedness to those who have freely made available the origi¬nal maps on which the illustrations for Chapter 5 have beenbased. A great number of original drawings had to be madein order to produce the map examples in colour. Drawingsfor maps 5.2.2.1, 5.2.2.2 and 5.2.2.3 were made in theDepartment of Engineering Geology and Hydrogeology,Comenius University, Bratislava (Czechoslovakia); thelegends for these maps and the drawings for all the other

maps were undertaken by Eric Lawson, Department ofGeology, University of Newcastle upon Tyne (England).Miss A. Thwaites and Mrs S. Gaynor of the same depart¬ment typed the many early versions of the text and the finalmanuscript. Without this very considerable help, which isgratefully acknowledged, this first major achievement of theIAEG Commission on Engineering Geological Maps couldnot have been brought to fruition.

[A. 38] SC.74/XVII.15/A

79

Acknowledgements 9

Members of the commission would wish to record their in¬

debtedness to those who have freely made available the origi¬nal maps on which the illustrations for Chapter 5 have beenbased. A great number of original drawings had to be madein order to produce the map examples in colour. Drawingsfor maps 5.2.2.1, 5.2.2.2 and 5.2.2.3 were made in theDepartment of Engineering Geology and Hydrogeology,Comenius University, Bratislava (Czechoslovakia); thelegends for these maps and the drawings for all the other

maps were undertaken by Eric Lawson, Department ofGeology, University of Newcastle upon Tyne (England).Miss A. Thwaites and Mrs S. Gaynor of the same depart¬ment typed the many early versions of the text and the finalmanuscript. Without this very considerable help, which isgratefully acknowledged, this first major achievement of theIAEG Commission on Engineering Geological Maps couldnot have been brought to fruition.

[A. 38] SC.74/XVII.15/A

79

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Engineering geological maps; a guide to their preparation; Earth