Quaternary Geomorphology

A Workshop for P.G. Candidates

December 18, 2010

Dr. Don Thieme

• Geochronology, Glacial Intervals, Isotopic Dating, etc...

• Glacial Landforms and Sedimentary Deposits

• Soil Classification and Paleosols

• Sea Level and Coastal Geomorphology

Soil Classification and Paleosols

Soil• Engineering definitions -

• all unconsolidated materials above bedrock (regolith)

• any material that can be moved without blasting

• Soil Science definition - A natural body, occurring at the Earth's surface, consisting of layers or horizons of mineral and organic materials, capable of supporting plants out-of-doors.

• Most of the elements essential for plant growth are obtained from soil.

Soil Formation

• a continuous interaction between the Earth's solid crust and the biosphere

• new soil material is added• from below by weathering of rock• from above as sediment is transported to the

soil surface by• water (alluvial)• gravity (colluvial)• wind (aeolian)

Sediment

• solid material settling out of a fluid• weathered rock detritus• matter deposited by

• water (alluvial)• wind (aeolian)• gravity (colluvial)

• Clasts are particles in sediment or sedimentary rock which derive from preexisting rock

Udden-Wentworth Scale

Clay as particle size [< 2(4) microns] but alsomineral group (phyllosilicates)

Phi = - log D in millimeters

Geometric reduction: 1/2, 1/4, 1/16,...

Gravel is coarser than 2 mm

Sand is 1/16 - 2 mm, visible to naked eye.

Silt is too small to see but can be felt.

Property Sand Silt Clay

Particle diameter (mm) 2.0 - 0.05 0.05 - 0.002 < 0.002

Means of observation Naked eye Microscope Electron microscope

Dominant minerals Primary Primary and secondary

Primary

Attraction of particles for each other Low Medium High

Attraction of particles for water Low Medium High

Retention of plant nutrients Very low Low High

Consistence when wet Loose, gritty Smooth Sticky, malleable

Consistence when dry Very loose, gritty

Powdery, some clods

Hard clods

Three Major Particle Sizes

Soil Texture

Soil Property Sandy Loam Clayey

Aeration Excellent Good Poor

Drainage Excellent Good Poor

Mineral Content Low Medium High

Water Holding Capacity Low Medium High

Workability Easy Moderate Difficult

Unified Soil Classification System (USCS)

Basis for USCS• Percentage of gravels, sands and fines• Shape of the grain size distribution curve• Plasticity

Three Categories• Coarse-grained (G for gravel; S for sand)• Fine-grained (M for silt; C for clay• Highly organic (O for organic; P for peat)

ML (low plasticity clayey silt)

SP (Poorly-graded sand) (Well "graded" sedimentis actually poorly sorted.)

Major Divisions (USCS) Symbol Description

GW Well-graded gravelsCLEANGRAVELS(< 5% fines)

GP Poorly-graded gravels

GM Silty gravels

GRAVEL ANDGRAVELLY

SOIL(>50% coarser

than no. 4)GRAVELS

WITH FINES(>12% fines)

GC Clayey gravels

SW Well-graded sandsCLEAN SANDS(<5% fines)

SP Poorly-graded sands

SM Silty sands

COARSEGRAINED

SOILS

(> 50% largerthan no. 200

sieve)

SAND ANDSANDY SOIL

(>50% finer thanno. 4)

SANDS WITHFINES

(>12% fines)SC Clayey sands

Major Divisions (USCS) Symbol Description

ML Inorganic or clayey silts of low plasticity

CL Inorganic lean clays

SILTS ANDCLAYS

(low plasticity)

OL Organic silts and clays of low plasticity

MH Elastic silts (micaceous or diatomaceous soils)

CH Inorganic clays or fat clays

FINEGRAINED

SOILS

(50% or >50%finer than no.

200 sieve)

SILTS ANDCLAYS

(high plasticity)

OH Organic silts and clays of high plasticity

HIGHLY ORGANICSOILS

PT Peats and Swamp soils with high organiccontent

Soil Forming Factors

• Climate• Organic Matter• Parent Material• Relief• Time

S = f (cl, o, p, r, t) - equation of Hans Jenny

Soil Genesis

• The properties of a soil formed in any given location, the horizons present, and their sequence depends on the combination of soil forming factors present.

• Prairie: A-B-C• Floodplain: A-C-A-C-A-C• Forest: O-A-E-B-C

Pedogenic Regimes

• Laterization• Removal of Silica• Dissolution of nearly all minerals, leaving

• Quartz• Iron and Aluminum Oxides

• Rapid decomposition of Organic Matter

• Laterite Soils are classified as Oxisols under the USDA Soil Taxonomy

Lateritic soil near Savusavu on the Fijian Island of Vanua Levu

Pedogenic Regimes

• Podzolization• Acid soil solution results in

• Elluviation of A and/or E horizons• Illuviation of Iron and Aluminum Oxides, Clay,

and Organic Matter down profile into B horizon(s)• Acid organic litter and limited nutrient

requirements (Boreal Forest, Coastal Plain of SE USA)

• Podzol soils are classified as Spodosols in the USDA Soil Taxonomy

"Podzolic" Soil Profile

(Spodosol) on Trail Ridge at Hoboken, GA

Pedogenic Regimes

• Gleization• waterlogged environment

with poor drainage• dark, highly organic A

horizon• lack of oxygen (anaerobic

condition) inhibits decay• low chroma and mottling

in B horizon

"Gleyed" Bg and Cg Soil Horizons in a Histosol profile

Pedogenic Regimes

• Calcification• CaCO3 carried downward in

profile• concentrated in B horizon,

sometimes as hardpan• capillary water and grass

roots carry CaCO3 back toward surface

"Calcic" Bk Soil Horizon in a Mollisol profile

Pedogenic Regimes

• Salinization• Salts carried downward in profile• Chlorides (CaCl, NaCl)

• Sulfates (CaSO4, Na2SO4)

• Toxic to most plants and soil organisms• Salic soils in western United States support

only sage and "saltbush"

Kingdom Order 12

Phylum Suborder 60

Class Great Group 303

Order Subgroup

Family Family

Genus Series >17,000

Species Phase

Biology Soil Science Number

USDA Soil Taxonomy

Ultisols, Spodosols, Entisols, Histosols, Alfisols

SOIL MAPPING UNITS

Series - basic unit of mapping for county soil surveys in the United States. Soils mapped as one series are similar in all major profile characteristics

Phase - subdivision based upon some important deviation that influences the use of the soil.• Texture• Drainage Class• Slope• Stoniness• Salt Content

SOIL MAPPING UNITS

Consociation - should be 50% pure soil that represents one phase of one soil series. There should be less than 15% inclusions of contrasting soils that differ in major profile characteristics.

Complex - contains two or three distinctly different soil series which occur so closely adjacent that they cannot be mapped separately on detailed map sheets.Association - maps at 3rd order or higher may group soils together which could be distinguished on detailed map sheets

COUNTY SOIL SURVEYS

General Soil Map - in color at a scale of approximately 1:200,000 showing soil associations which correspond to major physiographic regions in a county of the United States

Detailed Map Sheets - folded in the back of the report as an overlay on aerial photographs at 1:20,000

Profile Descriptions - representative "pedon" of each series

COUNTY SOIL SURVEYS

Associations and Complexes descriptions may include useful summaries of regional physiography and local landformsSoil Catena diagrams show how soils vary across a landscape (RELIEF)

Characterization data in Tables at the back of each survey.• Older characterization focused on

agricultural requirements (yields, suitability, drainage, etc...)

• Newer characterization includes wildlife habitat, forestry, waste disposal, ...

Soil CatenaSoil Catena

Catena diagram for Plymouth County, Massachusetts

Paleosols

• soil formed on a landscape of the past

• can sometimes be classified into a soil

order

• record of past climate

• Formation of Soils and Deep Regoliths occurred primarily during interglacial intervals in the Quaternary• particularly in temperate latitudes• more gradual and less discrete than glacial processes of deposition and erosion

Dune-Interdune Soils

• in Mauritania and Mediterranean region bordering Sahara Desert• Early Holocene paleosol found on summit and shoulder positions rerpresenting periods of moist climate

Soil Horizons and Time

Soil Orders and Time

Interglacial Paleosols, USA

Sangamon

Yarmouth

Tibetan Plateau,Western China

Soils across a Fault Scarp(Wasatch Fault Zone, Utah)

County Dump Fault, New Mexico

• 500 thousand years of normal faulting with intervening periods of soil formation

• Soils show varying degrees of calcification, development of Bk horizons

• Hachures are spaced in proportion to degree of soil development

Soils disrupted by the La Jencia fault, New Mexico

Geoarcheology - Lubbock Lake, TX