Chapter10 - Chapter 10 Weathering, Karst Landscapes, and...

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Unformatted text preview: Chapter 10 Weathering, Karst Landscapes, and Mass Movement Chapter 10 Reading P. 317 319 P. 322 physical weathering, frost action P. 324-325: carbonation & solution P. 325-330: karst topography & landscapes P. 331 335: classes of mass movements Weathering, Karst Landscapes, and Mass Movement Chapters 8 & 9: endogenic (internal) processes landforms Plate tectonics, folding, faulting, earthquakes, volcanoes During and after formation of landscape, exogenic (external) processes wear it down This chapter: physical and chemical weathering Weathering Weathering: general term applied to combined action of processes that cause rocks to be disintegrated physically and decomposed chemically due to exposure at or near surface Weathering processes release minerals from bedrock for soil formation Landmass Denudation Geomorphology : science of origin, evolution, spatial distribution of landforms Denudation : process that wears down or rearranges landforms Principal denudation processes that affect surface materials: Weathering Mass movement Erosion Transportion Deposition Continuing struggle between Earths internal and external processes Surface tries to maintain equilibrium If there are changes to the surface, balance is upset and surface tries to restore balance Dynamic equilibrium model : there is a balancing act between tectonic uplift and subsequent lowering (reduction) by weathering and erosion Endogenic events such as faulting and uplift are destabilizing events Sometimes exogenic events such as heavy rainfall and forest fires are, too After a destabilizing event, a landform system reaches a geomorphic threshold There is enough energy to overcome resistance against movement Over time, dynamic equilibrium model has following pattern: Stability Destabilizing event Period of adjustment (which requires many of the processes in this and the next few chapters) Stability again Think of a healthy person receiving a health insult broken bone, influenza Slopes Material becomes loosened by weathering Susceptible to erosion and transportation Forces of erosion must overcome those of friction, inertia and cohesion of particles to each other Gravity often overcomes friction Weathering Surface and subsurface rocks disintegrate into mineral particles or dissolve in water These materials are then transported away by water, wind, waves and ice Bedrock = underlying parent rock Upper surface of bedrock weathers to broken up rock regolith Physical Weathering Also called mechanical weathering Rock is broken and disintegrated without chemical alteration Breaking up rock increases surface area vulnerable to chemical weathering Several processes: Frost action Crystallization Hydration Pressure-release jointing Frost Action (freeze-thaw) Water expands during freezing up to 9% of its original volume...
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This note was uploaded on 04/20/2008 for the course GEOS 200 taught by Professor Hanchette during the Spring '08 term at University of Louisville.

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Chapter10 - Chapter 10 Weathering, Karst Landscapes, and...

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