+ All Categories
Home > Documents > Weathering and Soils

Weathering and Soils

Date post: 07-Jan-2016
Category:
Upload: teenie
View: 26 times
Download: 0 times
Share this document with a friend
Description:
Weathering and Soils. Granite headstone in Southern Vermont. Weathering and Soils. Marble headstones in Southern Vermont. Weathering and Soils. Mechanical Weathering- the physical breakdown of rocks Chemical Weathering- reaction of rocks with water, acids, oxygen, etc. - PowerPoint PPT Presentation
Popular Tags:
59
Weathering Weathering and Soils and Soils
Transcript
Page 1: Weathering and Soils

Weathering Weathering and Soilsand Soils

Page 2: Weathering and Soils

Marble headstones in Southern Vermont

Weathering Weathering and Soilsand Soils

Granite headstone in Southern Vermont

Page 3: Weathering and Soils

Weathering and SoilsWeathering and Soils MechanicalMechanical Weathering- the physical Weathering- the physical

breakdown of rocksbreakdown of rocks ChemicalChemical Weathering- reaction of rocks Weathering- reaction of rocks

with water, acids, oxygen, etc. with water, acids, oxygen, etc.

Page 4: Weathering and Soils

Mechanical Mechanical WeatheringWeathering

Page 5: Weathering and Soils

Tectonic Tectonic JointingJointing

Mechanical WeatheringMechanical Weathering

Page 6: Weathering and Soils

ExfoliationExfoliationMechanical WeatheringMechanical Weathering

Page 7: Weathering and Soils

ExfoliationExfoliationMechanical WeatheringMechanical Weathering

Page 8: Weathering and Soils

ExfoliationExfoliationMechanical WeatheringMechanical Weathering

Page 9: Weathering and Soils

Chemical Chemical WeatheringWeathering

Solution:Solution:HH22O + COO + CO22 = =

HH22COCO33 ( H ( H++ + HCO + HCO33-- ) )

in air (acid rain)in air (acid rain) acidacid

gasgasLimestone dissolves readilyLimestone dissolves readily

CaCOCaCO33 + 2 H + 2 H++ (aq) = (aq) =

CaCa+2+2 + CO + CO22 + H + H22OO

Page 10: Weathering and Soils

Chemical WeatheringChemical Weathering Solution: Karst TopographySolution: Karst Topography

Page 11: Weathering and Soils

Chemical WeatheringChemical Weathering Solution: Karst TopographySolution: Karst Topography

Page 12: Weathering and Soils

Chemical WeatheringChemical Weathering Karst Sinkhole- FloridaKarst Sinkhole- Florida

Page 13: Weathering and Soils

Chemical WeatheringChemical Weathering Karst Sinkhole- FloridaKarst Sinkhole- Florida

Page 14: Weathering and Soils

Chemical WeatheringChemical Weathering Tower Karst - ChinaTower Karst - China

Page 15: Weathering and Soils

Chemical WeatheringChemical Weathering

Oxidation:Fe2SiO4 + ½ O2 = Fe2O3 + SiO2

Page 16: Weathering and Soils

Chemical WeatheringChemical Weathering

Page 17: Weathering and Soils

Chemical Weathering Chemical Weathering Differential WeatheringDifferential Weathering

Page 18: Weathering and Soils

Chemical WeatheringChemical Weathering Differential WeatheringDifferential Weathering

Weathering can preferentially dissolve out mafics & increase the sialic component in sediments to yield “granite”

Page 19: Weathering and Soils

Chemical WeatheringChemical WeatheringWhat happens when granite is weathered?

The biotite and hornblende will undergo hydrolysis to form clay, and oxidation to form iron

oxides.

The feldspars will undergo hydrolysis to form kaolinite (clay) and release Na+ and K+ ions into solution

The quartz (and muscovite, if present) will remain as residual minerals because they are very resistant to weathering.

Page 20: Weathering and Soils

Idealized soil profile from a humid climate at middle latitudes

Zon

e of

Lea

chin

g

Page 21: Weathering and Soils

Horizon Development and Horizon Development and Climate Climate

Page 22: Weathering and Soils

Soil textural classesSoil textural classes

Page 23: Weathering and Soils

Topsoil ecosystem Topsoil ecosystem in a temperate in a temperate climateclimate

Page 24: Weathering and Soils

Effect of climate on soil developmentEffect of climate on soil development

Page 25: Weathering and Soils

Chemical WeatheringChemical Weathering

Transported SoilsTransported Soils

Page 26: Weathering and Soils

Wind-blown Glacial Wind-blown Glacial LoessLoess Deposits Deposits

Page 27: Weathering and Soils

Wind-blown Glacial Wind-blown Glacial Loess DepositsLoess Deposits

Page 28: Weathering and Soils

The Principal Soil TypesThe Principal Soil Types

Page 29: Weathering and Soils

Effect of climate on soil typesEffect of climate on soil types

tundra soils

Precipitation

Tem

pera

ture

cold

hot hot

coollow high50 cm/yr

pedalferspedocals

laterites

tundra soils

Page 30: Weathering and Soils

Principal soil types in the USAPrincipal soil types in the USA

Page 31: Weathering and Soils

Effect of climate on soil typesEffect of climate on soil types

A typical pedocal with A typical pedocal with white white calichecaliche (CaCO (CaCO33) )

deposits in a shallow B deposits in a shallow B horizonhorizon

Page 32: Weathering and Soils

Effect of climate on soilsEffect of climate on soils

Making Making laterite laterite bricksbricks

Temple at Temple at Angkor Angkor

Wat Wat CambodiaCambodia

(700 yrs (700 yrs old)old)

Laterite

Tundra soil

Page 33: Weathering and Soils

A Newer A Newer Classification Classification of Soil Typesof Soil Types

Pf

Pc

Pf

Pf, Pc

L

Pf, L

Page 34: Weathering and Soils

Rates of soil formation:Rates of soil formation:

Central USA: ~ 1 cm/100 years in very porous Central USA: ~ 1 cm/100 years in very porous and permeable rockand permeable rock

Humid N. Carolina: ~ 1 cm/5 yearsHumid N. Carolina: ~ 1 cm/5 years““

Granite may require over 1000 years for a cmGranite may require over 1000 years for a cm

Page 35: Weathering and Soils
Page 36: Weathering and Soils

Both Ends of the Erosion ProblemBoth Ends of the Erosion Problem

Serious Serious soil erosionsoil erosion and gully and gully formation related to diversion of formation related to diversion of water runoff over a few months water runoff over a few months in central Californiain central California Sediment pollutionSediment pollution following following

heavy rains in North Carolinaheavy rains in North Carolina

Page 37: Weathering and Soils

Soil DegradationSoil Degradation ErosionErosion DeforestationDeforestation Agricultural depletionAgricultural depletion Contamination - PollutionContamination - Pollution

SalinizationSalinization PesticidesPesticides Chemical additions and spillsChemical additions and spills

UrbanizationUrbanization DesertificationDesertification OvergrazingOvergrazing

Page 38: Weathering and Soils

Raindrop impact: Raindrop impact: millions in a single millions in a single shower hit at ~ 30 mphshower hit at ~ 30 mph

Soil ErosionSoil Erosion

Page 39: Weathering and Soils

Rill-wash and gullying in loose Rill-wash and gullying in loose and poorly-consolidated soilsand poorly-consolidated soils

Soil ErosionSoil Erosion

Page 40: Weathering and Soils
Page 41: Weathering and Soils

Soil Lost (tons/km2/yr) % runoffWoods ~ 0 0.12Grass 10 6.5Corn 18087 42Fallow 17050 49

Soil Erosion for Various Uses

Soil ErosionSoil Erosion

Page 42: Weathering and Soils
Page 43: Weathering and Soils
Page 44: Weathering and Soils

Number of dust storms during the month of March, 1936Number of dust storms during the month of March, 1936

Soil ErosionSoil Erosion

Page 45: Weathering and Soils

Effects of logging in MadagasgarEffects of logging in Madagasgar

Page 46: Weathering and Soils

Soil ErosionSoil Erosion

Figure 3.12:Figure 3.12: (a) a natural forested slope(a) a natural forested slope(b) the same slope following a clearcut(b) the same slope following a clearcut

Page 47: Weathering and Soils

Soil ErosionSoil Erosion

Figure 3.12:Figure 3.12: (c) the same slope after conversion to farmland(c) the same slope after conversion to farmland(b) the same slope following urbanization(b) the same slope following urbanization

Page 48: Weathering and Soils

Soil ErosionSoil Erosion

1968 motorcycles 1968 motorcycles first come to Deer first come to Deer

Creek near Creek near Bakersfield, CABakersfield, CA

1972 after only 4 1972 after only 4 years of ORV use years of ORV use little vegetation or little vegetation or

topsoil remainstopsoil remains

Page 49: Weathering and Soils

Soil ErosionSoil ErosionORV users increased ORV users increased from 21 to 38 million from 21 to 38 million

between 1982 and 1992between 1982 and 1992

ATVs rip through a marsh in ATVs rip through a marsh in West VirginiaWest Virginia

Great Grizzly Hike, MontanaGreat Grizzly Hike, Montana

Page 50: Weathering and Soils

Soil ErosionSoil Erosion

1985 photo of bulldozer and jeep tracks in 1985 photo of bulldozer and jeep tracks in Alaskan tundra made in 1946Alaskan tundra made in 1946

Page 51: Weathering and Soils

Soil ErosionSoil Erosion

Page 52: Weathering and Soils

Salt accumulation due to irrigation in Salt accumulation due to irrigation in an arid climate: San Fernando Valleyan arid climate: San Fernando Valley

Page 53: Weathering and Soils

Worldwide Distribution of Salt-affected SoilsWorldwide Distribution of Salt-affected Soils

Page 54: Weathering and Soils
Page 55: Weathering and Soils

Chemical Contamination of SoilsChemical Contamination of Soils

Page 56: Weathering and Soils

Grain production Grain production levels off while levels off while population population continues to growcontinues to grow

Page 57: Weathering and Soils

Strip-croppingStrip-croppingand and

Contour plowingContour plowing

Combating Soil DegradationCombating Soil Degradation

Page 58: Weathering and Soils

Rice terraces in Rice terraces in AsiaAsia

Combating Soil DegradationCombating Soil Degradation

Page 59: Weathering and Soils

No-tillNo-tillFarmingFarming

Combating Soil DegradationCombating Soil Degradation


Recommended