Erosion

Erosion

• The movement of soil by wind or water to some new location. (naturally a slow process but speeds up quickly when it is exposed)

• billions of tons of exposed topsoil are lost each year to erosion

• In your notes, list 5 ways that the process of erosion could be sped up.

Rainsplash

• A Single Raindrop

History

• The invention of the plow greatly increased the amount of erosion by exposing large areas of farmland

• Early colonists would grow one crop (monoculture) in the same place every year until the nutrients were used up and then they would move on leaving exposed soil behind.

• Colonists moved west to the great plains where the soil was rich in organic matter.

• “I felt I was becoming a slave to the land. But I held on to the thought that this land had to be stopped from blowing. Often I was so full of dust that I drove blind, unable to see even the radiator cap on my tractor or hear the roar of the engines. But I kept driving on and on, by guess and instinct. I was making my last stand in the Dust Bowl.”

• Farmland increased rapidly and by the 1930’s giant dust clouds of soil blew across the county due to dry exposed soil. (dust bowl)

Natural Resources Conservation Service

• The government created the Soil conservation Service (SCS) (now the NRCS) within the Dept. of Agriculture to conserve the nation’s soils.

• The NRCS maps and surveys soil to plan methods of soil conservation.

• Modern technology has allowed the U.S. to increase its production allowing it to produce more food than needed.

• In the 70’s the U.S. started growing grains for other countries adding to the erosion problem (dust storms in CA.)

• Many conservation practices are still ignored when using large machinery because many practices are more difficult to do on a large scale.

• Besides farming, highway construction, building construction, overgrazing and some logging activities all increase the rate of erosion

Types of Erosion: Rill• Occurs on gentle slopes of exposed soil. Water

creates small channels a few inches deep. It may turn into gully erosion on steeper slopes.

Types of Erosion: Gully• Occurs on steep slopes. Fast moving water cuts

deep ditches into the soil that can change the landscape.

Types of Erosion: Sheet• Gradual removal of

topsoil by wind or water.

• Occurs in thin layers on very gentle to non-sloping exposed soils.

• It can be seen by blowing dust and muddy water.

Types of Erosion: Mass

• Large movements of soil due to gravity.

• Several Types:– Landslide– Mudslide– Rockfall– Creep

Landslide

Mudslide

Rockfall

Creep

• National Geographic Mudslide Video• Induced Rockfall