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Lecture 12

GEG 1301 Lecture Notes - Lecture 12: Dune, Landform


Department
Geography
Course Code
GEG 1301
Professor
Denis Lacelle
Lecture
12

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Erosion
November 19, 2015
-Similar to weathering, but the material is removed after breakdown
-Occurs at all scales (from cm to km) and all landscapes (glacial, coastal, karst, Aeolian)
-Erosional energy comes from potential and kinetic energy caused by
Uplifting: increases potential energy (what goes up must come down)
Water and ice: move under the action of gravity, converts potential → kinetic
-4 stages of erosion:
Detachment: Detachment forces (weathering, quarrying/plucking, abrasion,
raindrop impact/rainsplash effects) must overcome all resistant forces (friction,
cohesion, cementation, interlocking crystals) to release the material
Entrainment: The sediments are incorporated into the fluid flow (air, water, ice)
-Must still overcome resistant forces
-Critical entrainment velocity varies with fluid type and particle size
Transport: 4 methods of transportation (suspension, saltation, traction & in
solution/dissolved)
Deposition: May be sorted or unsorted
-Sorted: Sorting of grain sizes due to settling out at different velocities
Coarser material is deposited first → finer material
-Unsorted deposits have a wide range of grain sizes in one place
Common for glacial deposits
-Chemical precipitation also occurs
-Landscapes and landforms
Landform: A single, visible feature (mountain, sinkhole, sand dune, water feature)
-Discrete product of a discrete process
Landscape: An aggregation of landforms, includes land cover
-Regional expression of processes
Ex. fluvial, glacial, Aeolian, costal, and karstic landscapes
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