Chapter 13 Outline

Chapter 13 Outline - Chapter 13 Weathering Karst Landscapes...

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Chapter 13: Weathering, Karst Landscapes, and Mass Movement Landmass Denudation Geomorphology - science of landforms- thr origin, evolution, form, spatial distribution; denudation - any process tht wears away/rearranges landforms; main denude processes- weathering, mass movement, erosion, transportation, deposition as produced by moving water, air, waves, ice: All influenced by gravity; interactions btwn structural elements of land/denude processes complex- struggle btwn Earth internal/external processes; differential weathering - more resistant cap rock protects supporting strata below; ideally, endogenic processes build initial landscapes , exogenic processes dvlp sequential landscapes of low relief, grad change, stability Geomorphic Models of Landform Development William Morris Davis (1850-1934) proposed erosion cyc/ geomorphic cycle model : landscape undergoes initial uplift that is accompanied by eroision/removal of materials; fr uplifted landscape, streams start flowing quicker, cutting more energetically, both upstream/deeper, frmng valleys Thought slope angle gradlly reduced, ridges/divides become rounded, lowered over time; & landscape evntlly evolved into old erosional surface; theory helped launch science of geomorph but not totally accurate, little academic support; not generally accepted today but thinking influential Dynamic Equilibrium View of Landforms Preferred dynamic equilibrium model stresses balance among force, form, process; summarizes this balancing act btwn: tectonic uplift/reduction by weathering/erosion, and resistance of rocks/attack of weathering, erosion; dynamic equilb shows trend over time- landscapes in this feature: Ongoing adaptations to contsly changing conditions of rock structure, climate, local relief, elevation; landscape- open sys w/vry variable inputs of energy, materials: uplift creates potential energy of position above sea lvl, thus disequilb btwn relief, energy Sun’s radiant energy converts heat energy ; hydrologic cyc=> kinetic energy thru mechanical motion; chem energy fr atmos, rxns in crust; in response to thse, landforms adjust equilb; endogenic (quakes, eruptions)/exogenic events (rainfall, fire) may destabilize- following thse, landform sys arrives at: Geomorphic threshold - pt at which enough energy to overcome resistance against movement; here, sys breaks thru to new equilb as landform adjusts; over time, pattern: 1) Equilb stability, 2) Stabilizing event, 3) Per of adjustment, 4) Dvlpt of new, diff condition of equilb stability Slow, conts-change events eg soil dvlpmt/erosion usu maintain approx equilb condition; dramatic events eg landslide need longer recovery times before equilb reestablished Slopes Material loosened by weathering may be eroded/transported, tho attacking agnets must overcome friction, inertia, particle cohesion; slope angle must be steep enough too; slopes /hillslopes curved, inclined surfaces tht form boundaries of landforms; usu have convex upper
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This note was uploaded on 06/24/2008 for the course GEOG 1 taught by Professor Okin during the Fall '06 term at UCLA.

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Chapter 13 Outline - Chapter 13 Weathering Karst Landscapes...

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