Cobble Cobble

Field Identification and Description of Soils (after Table 7, BS 5930:2015)

SOIL GROUP

PRINCIPLE SOIL TYPE

PARTICLE SIZE, MMVISUAL

IDENTIFICATION

RELATIVE DENSITY/ CONSISTENCY

DISCONTINUITIES BEDDING COLOUR COMPOSITE SOIL TYPES (MIXTURES OF BASIC SOIL TYPES) MINERALOGY PARTICLE SHAPE PRINCIPAL SOIL

TYPETERTIARY

CONSTITUENTS GEOLOGICAL UNITTERM / FIELD TEST

VERY

CO

ARS

E SO

ILS Large

BoulderOnly seen complete in pits or exposures

Often difficult to recover whole from boreholes

None defined.Qualitative description of packing by inspection and ease of excavation

Describe spacing of features such as fissures, shears, partings, isolated beds or laminae, desiccation cracks, rootlets, etc

FissuredSoil breaks into blocks along unpolished discontinuities

ShearedSoil breaks into blocks along polished discontinuities

Describe thickness of beds in accordance with geological definition

Alternating layers of different types

Inter-beddedor inter-laminated

Prequalified by thickness term if in equal proportions

Otherwise thickness of and spacing between subordinate layers defined

LIGHTNESS

LightDark

CHROMA

PinkishReddishYellowishOrangishBrownishGreenishBluishGreyishetc

HUE

PinkRedOrangeCreamBrownYellowGreenBlue WhiteGreyBlack

More than 3 colours is multicoloured

Colours may be mottled

For mixtures involving very coarse soils see BS 5930:1999 Cl41.4.4.2

AngularityVery angularAngularSubangularSubroundedRoundedWell rounded

ShapeCubicFlatElongate

Terms can include:

shell fragmentspockets of peatgypsum crystalsbrick fragmentsrootsrootletsfossil rootsfossil rootletsplastic bagsetc

with rare

with occasional

with numerous/frequent/abundant

Proportions de-fined on a site or material basis, or subjectively

Name in accordance with published geological maps, memoirs or sheet explanation

For example:

RIVER TERRACE DEPOSITS

GLACIAL SAND AND GRAVEL

MADE GROUND

BRICK EARTH

DARTFORD SILT MEMBER

WEATHERED CHARMOUTH MUDSTONE FORMATION

CLAY WITH FLINTS

OXFORD CLAY

GLACIAL TILL

EMBANKMENT FILL

ALLUVIUM

TOPSOIL

UPPER MOTTLED CLAY, LAMBETH GROUP

Boulder

Cobble

COA

RSE

SOIL

S (O

VER

65%

SA

ND

AN

D G

RAVE

L SI

ZES)

Coarse

Easily visible to naked eye; particle shape can be described; grading can be described

BOREHOLE WITH SPT N VALUE

TERM BEFORE PRINCIPAL SOIL TYPE

PROPORTION OF SECONDARY (SEE NOTE A)

Medium Very loose. 0-4

slightly (sandy)(See note B) <5%

Fine Loose. 4-10

(sandy)(See note B)

5 – 20%(See note C)

Coarse

Visible to naked eye; no cohesion when dry; grading can be described

Medium dense. 10-30

very (sandy)(See note B)

>20%(See note C) Mineralogical terms can include:

glauconiticmicaceouscalcareous (see below)shellyorganic

slightly (glauconitic)

(glauconitic)

very (glauconitic)

Proportions defined on a site or materi-al specific basis or subjectively

Medium Dense. 30-50

SAND AND GRAVEL About 50%

Fine Very dense. >50

TERM BEFORE PRINCIPAL SOIL TYPE

PROPORTION OF SECONDARY (SEE NOTE A)

FIN

E SO

ILS

(35%

SIL

T A

ND

CLA

Y SI

ZES)

CoarseOnly coarse silt visible with hand lens; exhibits little plasticity and marked dilatancy; slightly granular or silky to the touch; disintegrates in water; lumps dry quickly; possesses cohesion but can be powdered easily between fingers

Very soft. Finger easily pushed in up to 25mm; exudes be-tween fingers

slightly (sandy)(See note D) <35%

MediumSoft. Finger pushed in up to 10mm; moulded by light finer pressure

(sandy)(See note D)

35% - 65%(See note E)

FineFirm. Thumb makes impression easily; cannot be moulded by fingers; rolls to thread

very (sandy)(See note F)

>65%(See note E)

Dry lumps can be broken but not powdered between fingers; they also disintegrate under water but more slowly than silt; smooth to the touch; exhibits plasticity but no dilatancy; sticks to the fingers and dries slowly; shrinks appreciably on drying, usually showing cracks

Stiff. Can be indented slightly by thumb; cannot be moulded;

Silty CLAY

Clayey SILT

Terms used to reflect secondary fine constituents where this is important

Carbonate contentSlightly calcareous – weak or sporadic effervescence from HCICalcerous - clear but not sustained effervescence from HCIHighly calcerous - strong and sustained effervescence from HCI

Very stiff. Can be indented by thumb; cannot be moulded; crumbles

ORG

AN

IC S

OIL

S

CONDITION ACCUMULATED IN SITU TRANSPORTED MIXTURES NOTES

PEATPredominately plant remains, usually dark brown or black in colour, distinctive smell, and low bulk density; can include disseminated or discrete inorganic particles

Contains finely divided or discrete particles of organic matter, often with distinctive smell, may oxidise rapidly. Describe as for inorganic soils using terms above.

A Percentage coarse or fine soil assessed excluding cobbles and boulders

B Gravelly or sandy and/or silty or clayeyC Or described as fine soil depending on mass behaviourD Gravelly and/or sandyE Or described as coarse soil depending on mass behaviourF Gravelly or sandy

Fibrous peat Plant remains recognisable and retain some strength; water and no solids on squeezing TERM COLOUR

Pseudo-fibrous peat Plant remains recognisable and strength lost; turbid water and <50% solids on squeezing Slightly Organic Grey

Amorphous peat No recognisable plant remains; mushy consistency; paste and >50% solids on squeezing Organic Dark Grey

Very Organic Black

SAM

PLE

D

ESCR

IP-

TIO

NS:

Loose brown very sandy subangular fine to coarse flint GRAVEL with small pockets (up to 30mm) of clay (TERRACE GRAVELS)

Medium dense light brown gravelly clayey fine SAND. Gravel is fine (GLACIAL DEPOSITS)

Stiff closely sheared medium strength orange mottled brown slightly sandy slightly gravelly CLAY. Gravel is fine and medium of quartzite. (REWORKED LONDON CLAY)

Firm thinly laminated grey silty CLAY with closely spaced thick laminae of sand (ALLUVIUM)

Plastic brown clayey amor-phous PEAT

200

63

20

2

0.63

0.2

0.063

0.02

0.0063

0.002

6.3

630

SCALE OF SPACING OF DISCONTINUITIES

TERM /MEAN SPACING, MM

Very widely>2000

Widely2000-600

Medium600-200

Closely200-60

Very closely 60-20

Extremely closely20-6

Firm Spongy Plastic

Fibres compressed

together

Very compressible

open structure

Can be moulded in

hand; smears fingers

SCALE OF SPACING OF DISCONTINUITIES

TERM /MEAN SPACING, MM

Very thickly bedded>2000Thickly bedded2000-600Medium bedded600-200Thinly bedded200-60Very thinly bedded 60-20Thickly laminated20-6Thinly laminated<6

Silt Silt

Sand Sand

Gravel

Boulder Boulder

Gravel

Clay Clay

ROCK MATERIAL ROCK MASS

ROCK MATERIAL ROCK NAME GENERAL WEATHERING DISCONTINUITIES

DIMENSION STRENGTH STRUCTURE & FABRIC COLOUR TEXTURE GRAIN SIZE SEDIMENTARY IGNEOUS METAMORPHIC MINOR

CONSITUENTSFORMATION

NAME ORIENTATION SPACING PERSISTANCE TERMINATION ROUGHNESS WALL STRENGTH APERTURE INFILLING SEE PAGE SETS

2000mm

>250MPa extremely strong

Rings on hammer blows. Only chipped with geological hammer

Use standard geological

termsVery thickly

LIGHTNESS

LightDark

CHROMA

PinkishReddishYellowishOrangishBrownishGreenishBluishGreyishetc

HUE

PinkRedOrangeBrownYellowGreenBlue WhiteGreyBlack

Use standard geological terms

For example:

phaneritic

ophitic

porphytic

crystaline

amorphous

Massive

FoliatedDescribe

using relative terms

rare

occasional

frequent

vugs

shells

pyrite

crystals

organics

colours

odours

Name according to published

geological maps and memoirs

UPPER CHALK

RESIDUAL MUDSTONE

SHERWOOD SANDSTONE

COAL MEASURES

MERCIA MUDSTONE

BORROWDALE GROUP

HUNT’S BAY OOLITE

TINTERN SANDSTONE

MANCHESTER MARL

ST BEES SHALE

MILLSTONE GRIT

Approach 1

Mandatory description

of all features associated with

weathering

Describe state and changes in:

Strength

Fracture state

Colour

Presence or absence of weathering products

Approaches 4 or 5

Classify only if useful and unambiguous

Dip direction and dip

e.g. 220/50

Dip amount only in cores

Extremely widely >6m Very high

>20m

x outside

exposure

rwithin rock

dagainst

discontinuity

Cannot normally be described in

cores

Record size of exposure

LARGE SCALE (M)

WAVINESSCURVATURE

STRAIGHTNESS

Use standard strength terms

(column 2)

Support by using:

Field strength tests

Point load

Schmidt hammer

Other index tests

Visual assessment

Cannot normally be described in

cores

Extremely wide >1000mm

Cannot normally be described in

cores

Surface staining (colour)

Soil infilling (describe as

for soils – see over)

Cannot be described in

cores

CAN

NO

T BE

DES

CRIB

ED IN

CO

RES

Very widely 2 – 6m

High10 - 20m

630mm100 – 250MPaVery strong

Requires many hammer blows to break specimen

Thickly

COA

RSE

GRA

INED

CONGLOMER-ATE

BRECCIA

LIMESTONE

AGGLOMERATE

DOLOMITE

VOLCANIC BRECCIA

GRANITE

DIORITE

GABBRO

GNEISS

MIGMATITE

MARBLE

Widely0.6 – 2m

Medium 3 - 10m MEDIUM SCALE

(CM) AND SMALL SCALE

(MM)

Very wide 100 - 1000mm

200mm Medium Medium200 – 600mm

Low 1 – 3m

63mm Thinly Closely 60 – 200mm

Very low <1m STEPPED

ROUGH __ ____/ \__/

SMOOTH _ _ __/ \_/ \_/

STRIATED__|__|__|__|__

Wide 10 - 100mm50 – 100MPa

Strong

Rock broken by more than one hammer blow

20mm Very thinly Very closely 20 – 60mm

Discontinuous

Continuous in cores

6.3mmThickly

laminated/narrowly

Extremely closely <20mm

Take several readings

Report minimum, average and

maximum

e.g. 25/60/300

Moderately wide

2.5 - 10mm

25 – 50MPaMedium strong

Cannot be peeled with knife. Can be broken with one hammer blow

2mm

Thinly laminated/very narrowly

Terms include ;

bedded

laminated

foliated

banded

flow banded

UNDULATING ROUGH

/ \ / \ / SMOOTH

/ \ / \ / \ STRIATED

/ \ / \ / \ / \ / \

Open 0.5 - 2.5mm Mineral

coatings (e.g. calcite, chlorite,

gypsum, etc)

Moisture on rock surface

RECO

RD S

PACI

NG

AN

D O

RIEN

TATI

ON

OF

EACH

SET

0.63mm

MED

IUM

GRA

INED CO

ARS

E

SANDSTONEHALITE

GREYWACKE

QUARTZITE

TUFF

ANHYDRITE

MICROGRANITE

DOLERITE

MICRODIORITE

SCHIST

RHYOLITE

QUARTZITE

Partly open0.25 - 0.5mm Dripping water

0.2mm

MED

IUM

Tight0.1 – 0.25mm

Other - specify

Water flow measured per unit time on an individual discontinuity

or set of discontinuities

5 – 25MPaWeak

Can be peeled with difficulty. Point of hammer makes shallow indents

0.063mm FIN

E PLANAR ROUGH

^^^^^^^^^^^SMOOTH

______________

STRIATED- - - - - - - -

Very tight <0.1mm

Take several readings

Report minimum,

average and maximum

e.g. 7/120/550

0.02mm

FIN

E G

RAIN

ED

SILTSTONE

CHALK

GYPSUM

Fine grained TUFF

RHYOLITE

ANDESITE

BASALT

Record width, continuity

and relevant characteristics

of infill

Large >5l/sec

1 - 5MPaVery weak

Can be peeled with knife. Crumbles under firm hammer blows

0.006mm MEASURE AM-PLITUDE AND WAVELENGTH OF FEATURE

Medium0.5 – 5.0l/sec

0.002mm Small 0.05 – 0.5l/sec

0.6 – 1MPaExtremely weak

Gravel size lumps crush between finger and thumb. Indented by thumb nail

VERY

FIN

E G

RAIN

ED MUDSTONE

Very fine grained TUFF

CHERT

FLINT

OBSIDIAN

VOLCANIC GLASS

CRYP

TO-

CRYS

TAL-

LIN

E

Borehole core:Very strong dark greyish green fine grained quartz DOLERITE. Joints dip 25, widely spaced, with red penetrative staining to 15mm and locally weathered to moderately strong to 5mm penetration.

Trial pit:Weak white CHALK. Bedding fractures subhorizontal (040 - 065/05 - 15) closely spaced (80/110/200) light and clean. Joints predominately subvertical closely spaced (20/150/350) generally infilled with up to 3mm of yellowish white silt size comminuted chalk. Prominent joint sets at 150/70 and 220/80. Widely spaced subhorizontal bands of very closely spaced rinded flint cobbles.

Exposure:Moderately weak very thinly bedded reddish brown fine and medium grained SANDSTONE. Rare moderately weak light greyish green siltstone elliptical inclusions up to 40mm by 10mm. Small blocky jointing. Joint set 1: 045/75, medium spaced, medium persistence, terminations outside exposure, curved planar rough, weak friable up to 5mm penetration, moderately wide open, clean. Joint set 2: 110 - 130/70 - 90, closely spaced, low persistence, terminations outside exposure and against discontinuity, planar smooth weak friable up to 5mm penetration, tight clean. Bedding fracture set 3: 180 – 190/0 - 10, medium spaced, high persistence, no termination seen, straight stepped smooth, slightly polished, moderately open up to 1mm infilled with firm grey clay. Joints generally dry, local small flows.

FRACTURE STATESOLID CORE. Solid core is taken as core with at least one full diameter (but not necessarily a full circumference) measured along the core axis or other scan line between two natural fracturesTCR. Percentage ratio of core recovered (both solid and non-intact) to the length of the core run

SCR. Percentage of solid core recovered to the total length of the core runRQD. Total length of solid core pieces each greater than 100mm between natural fractures expressed as a percentage of total length of the core run

IF. Average length of solid core pieces between natural fractures over core lengths of relatively uniform characteristics, not core runsFI. Number of fractures per metre over core lengths of relatively uniform characteristics

Field Identification and Description of Rocks (in accordance with BS 5930:2015 and BS EN ISO 14689-1)