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4-2 Erosion NOTES
Name ____________________ Date _____
Erosion is the process where weathered rocks are transported and deposited in another located. Can be
influenced by: wind, gravity, water, glaciers
Wind Erosion
 Wind can pick up, transport and deposit great amounts of sediment
 Generally only very small particles are transported by wind
 Humid areas and areas of high vegetation are less susceptible to wind erosion
 Sediments are bound together
 Wind erodes deserts in 2 ways:
 Deflation-Small particles such as clay and silt are lifted and removed
 Abrasion-Rock surfaces are blown off by extreme wind
 Gravity causes erosion when material falls off of cliffs or elevated surfaces
 Material is very poorly sorted at the base of the cliff (big sediments mixed with small sediments)
 No time for material to be sorted by size
Water Erosion
 Streams erode their channels by abrasion and grinding
 Sediments become dissolved inside the stream (dissolved load)
 Sediments being carried by a stream can erode the banks as well
 Sheet Erosion-Erosion caused by runoff water. Runs along the surface in thin sheet
 Least detrimental
Rill Erosion-Water flows through very small flow paths down a hill
Gully Erosion-Water flows through a wide channel.
 Most detrimental
Glacial Erosion
 When glaciers move they pick up pieces of Earth’s landscape.
 Till-Sediment deposited by glaciers when they melt
 Poorly sorted when deposited
 Glacial erosion is the only type capable of moving boulders
How can humans control erosion
Planting rows of trees called windbreaks
Terracing hillsides
Plowing along the contours of hills
Rotating crops
What is Mass Movement?
 The transfer of rock and soil down-slope due to gravity
 Triggers of Mass Movement
 Classification of Mass Movements
 Rockfalls occurs when rocks or rocks fragments fall freely through the air.
Classification of Mass Movements
--extremely rapid movement of earth material or snow
 In a slide, a block of material moves suddenly along a flat, inclined surface.
Slides that include segments of bedrock are called rockslides.
Slumps A slump is the downward movement of a block of material along a curved surface.
Flows are mass movements of material containing a large amount of water.
Mudflows move quickly and carry a mixture of soil, rock, and water that has a consistency of wet concrete.
Earthflows move relatively slowly and carry clay-rich sediment.
Creep is the slow, downhill movement of soil and regolith.  slowest type of mass movement