GEOG 1F91 Lecture Notes - Drainage Divide, Hydraulic Action, Drainage Basin
21 Feb 2014
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Agents of erosion: what can move weathered material, gravity (mass wasting, water (coastal/fluvial, wind (aeolian, ice (glacial) Causes of slope failure: rainfall, undercutting, shocks or vibrations (traffic, earthquakes) Drainage systems: fluve = channeled water, drainage divide, stream flow. Normal: parallel, trellis, rectangular angles, angular (radial) Stretched dendritic (slope is steeper, water flows according to arrows ) Fractures or faults at right angles (karst -> limestone fractures at right. Water flows off the dome or peak: contorted. Canadian shield, no particular pattern: remember diastrophism? (folding sediment layers, folds create hills and valleys, water flows down hills and into valleys, add plutonic activity . Parallel/trellis pattern: volcanoes have cone shape, water/lava flows downhill, radial pattern. Energy considerations: water flowing down an energy gradient, from higher to lower potential energy. Stream erosion: critical erosion velocity, very strongly dependent on particle size, text fig. Relates particle size to energy: erosion occurs via, hydraulic action (water) (cavitation, abrasion (stuff in the water, stream gradient:
