Presentation on theme: "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."— Presentation transcript:
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
National Geographic Mudslide Video Induced Rockfall