Chapter 10Weathering, Karst

Landscapes, and Mass Movement

Elemental Geosystems 5e

Robert W. ChristophersonCharles E. Thomsen

Weathering, Karst Landscapes, and Mass Movement

Landmass DenudationWeathering ProcessesKarst Topography and LandscapesMass Movement Processes

WeatheringGeomorphology - Science of landformsWeathering – breaking up of landscapeErosion is transport of weathered materialEndogenic – Forces within EarthExogenic – Forces outside Earth

Dynamic equilibrium modelLandscape is balanced

Endogenic vs. ExogenicUplift vs. Weathering & ErosionGravity vs. Friction & CohesionWeathering vs. Resistance of rock

Balance changesLandscape changes in responseLandscape is balanced

Slope Mechanics and Form

Figure 10.3

Slope Mechanics and Form

Figure 10.3

WeatheringPhysical weathering disintegrates materialChemical weathering dissolves material

Weathering ProcessesFactors Influencing Weathering ProcessesPhysical Weathering Processes

Frost actionCrystallization (salt-crystal growth)Pressure-release jointing

Chemical Weathering ProcessesHydration and hydrolysisOxidationCarbonation and solution

WeatheringInfluenced by climate

TemperatureWater

Physical composition and structureJointsChemicals of rock

Climate and weathering regimes

Regolith, Soil, and Parent Materials

Figure 10.4

Physical weatheringDisintegrates material

Mechanical processesFrost actionCrystallizationPressure release jointing

Physical WeatheringBack

Frost ActionWater expands up to 9% when it freezes

Physical Weathering

Figure 10.6

Joint-block Separation

Figure 10.6

Rockfall

Figure 10.7

CrystallizationSalt crystals grow as water evaporatesCrystals force apart grains in rock

Physical Weathering in

Sandstone

Figure 10.8

Pressure releaseExfoliation occurs as pressure is releasedSierras cooled 7 km under groundWhen material above is removed they expand and break apart

Exfoliation in Granite

Figure 10.9

Exfoliation in Granite

Figure 10.9

Exfoliation in Granite

Figure 10.9

Chemical weatheringDissolves materialSpheroidal weatheringHydration and hydrolysisOxidationCarbonation

Figure 13.12

Spheroidal weatheringCorners dissolve firstCreates rounded landscape

HydrolosisChemicals combine with waterWater dissolves chemicals

HydrationChemicals within rock absorb water and expandInternal stress forces apart rock

CarbonationWater combined with CO2 makes carbonic acidCarbonic acid dissolves calciumLimestone is calcium rich and creates Karst topographyKarst needs 80% Ca with abundant joints

Chemical Weathering

Oxidation Chemicals combine with oxygenOxygen + chemicals = rust

Oxidation in Rock and Soil

Figure 10.12

Chemical Weathering

Figure 10.10

Karst Topography and LandscapesFormation of KarstLands Covered with SinkholesCaves and Caverns

Karst and Limestone Regions

Figure 10.13

Karst Topography

Figure 10.14

Sinkholes

Figure 10.15

Cavern Features

Figure 10.17

Mass Movement ProcessesMass Movement Mechanics

The role of slopesClasses of Mass Movements

Falls and avalanchesLandslideFlow Creep

Human-Induced Mass Movements

Madison River LandslideFigure 10.18

Mass Movement Classes

Figure 10.19

Physical Weathering

Mass Movements

Talus Slopes

Figure 10.20

Debris Avalanche,

Peru

Figure 10.21

Debris Avalanche

Figure 13.24

Gros Ventre Slide, Wyoming

Figure 10.22

Soil Creep

Figure 10.23

Solifluction

Figure 17.23

Figure 10.24

Scarification

End of Chapter 10

Elemental Geosystems 5e

Robert W. ChristophersonCharles E. Thomsen