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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
 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
Avalanches
--extremely rapid movement of earth material or snow
Slides
 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
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