Erosional ForcesWater

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Erosion• Everyday erosion takes place all around you.

– When it rains at your house, the rain washes away dirt and sediment from your yard and driveway.

– During P.E. class you notice that the wind is blowing away dirt from the baseball field and it gets in your eyes and mouth.

• Erosion: wearing away of surface material and moving them from one place to another.

• Erosion happens in 4 different ways all over Earth.

– 1) Water

– 2) Wind

– 3) Gravity

– 4) Glaciers

• Deposition: depositing or dropping sediments after they have been eroded from an area.

Water Erosion

• Water can be a very powerful force as you saw in the destruction of the Indonesian tsunami.

• Water wears away rock and other material sometimes in a slow way that takes many many years like in a slow moving river. At times water can erode dirt and rock very fast like in a flood, mudslide, or tsunami.

• Usually the steeper the land the faster the water and the faster the water erosion.

• As water moves downhill it is called runoff. Runoff creates small channels where the water flows. These channels get bigger and bigger.– Rills– Gully– Stream– River

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Water Erosion (Cont’d)

• Scientists classify rivers by identifying certain features that form as a result of erosion.– Flood plains

• Flat wide area of land along a river

– Meanders

• Looplike bend in the course of a river

– Oxbow Lake

• A lake formed by a river’s flow cutting off one of the meanders.

– Sinkhole

• Deep hole created by water eroding away the ground beneath.