PG. 71

Erosion and Deposition

Gravity’s Role in Erosion

Gravity pulls materials down slopeStreams wouldn’t flowAlso an agent of landslides, mud flows, and

avalanches

Erosion by water

Except for hurricanes and tornados, water has the greatest power to move masses of material

Erosion greatest when there is a large rapidly moving body of water

Water running down steep slopes also has a lot of power

Rill erosion- by running water in small channels on the side of a slope

Gully erosion- when a channel becomes deep and wide

Water erosion

Coastal deposition and erosion

Deposition- last step of erosion; materials are dropped in another location

When rivers enter a large body of water, it slows and deposits large amounts of sediments

Build up of sediments forms deltasContains fertile soilOcean currents can then form sand bars and

barrier islands

Deposition

Glacial Erosion

Only cover 10% of earth’s surfaceLarge-scale erosion

Wind Erosion

Occurs in areas with limited precipitation and high temperatures

Little vegetation to hold soil in placeWind barriers are used to prevent wind

erosionUsually just a row of trees planted

perpendicular to the direction of the wind.

Erosion by plants, animals, and humans

Plants and animals move weathered material with them

Human excavating aids in erosionEffects are minimal compared to wind, water,

and ice erosion