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Mass Movement: What causes the different types of mass movement?. Erosion is the process by which natural forces move weathered rock & soil from one place to another. What is the material moved by erosion called? sediment
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Mass Movement: What causes the different types of mass movement?
Erosion is the process by which natural forces move weathered rock & soil from one place to another.
What is the material moved by erosion called? sediment Sediment may include pieces of rock or soil or the remains of plants or animals
Agents of Erosion • In nature, sediment can be moved by: • Gravity (Mass Movement) • Water (Rivers, Streams, Groundwater) • Glaciers • Waves • Wind • These are known as the agents of erosion. • (The word ‘agents’ means the processes or ways that erosion occurs.)
Deposition * happens where agents of erosion drop or lay down sediment. • Sediment is deposited in: • Horizontal layers • layers become very thick after a long periods of time. • Oldest layers on the bottom • Law of Superposition.
Mass movement * happens when gravity moves sediment downhill. * can be rapid or slow and is caused by gravity.
Landslides * are the most destructive of the four types of mass movement. * Describe: Rock & soil slides quickly down steep slopes * Where does it happen? Where road builders cut through hills or mountains leaving behind unstable slopes.
Landslides http://en.wikipedia.org/wiki/Landslide http://carletong.wordpress.com/2009/04/27/paybacksamother/
Mudflows *are very dangerous. * Describe: The rapid downhill movement of a mixture of water (can be as high as 60%) rock, and soil. * What may trigger it? Often occur after heavy rains in a normally dry area.
Mudflows http://cache.virtualtourist.com/1827048-City_of_Plymouth_destroyed_by_Mud_Flows-Montserrat.jpg
Slump * occurs when one huge mass falls together. *Describe: Mass of rock & soil suddenly slip down a slope in one huge mass *What makes it happen? When water soaks the bottom of soil rich in clay
Slump Cartersville, Georgia
Creep * is very slow movement. *Describe: Barely noticeable, you eventually see the effects of the slow movement in telephone poles, fence posts & trees leaning at odd angles *What causes creep? From freezing & thawing of H2O in cracked layers of rock beneath the soil
Creep Bent tree trunk illustrating creep. National Zoo, Rock Creek Park, Washington, D.C. http://images.google.com/imgres?imgurl=http://facstaff.gpc.edu/~pgore/myphotos/other/creep.jpg&imgrefurl=http://facstaff.gpc.edu/~pgore/geology/geo101/masswasting.html&usg=__NXT2vQd6NNlaYppssy5JkhmQtO8=&h=357&w=300&sz=33&hl=en&start=7&um=1&tbnid=T5WrN7ZS1oqFeM:&tbnh=121&tbnw=102&prev=/images%3Fq%3Dcreep%2Bmass%2Bmovement%26hl%3Den%26sa%3DN%26um%3D1