Mass Movement What causes the different types of

Mass Movement: What causes the different types of mass movement? 1

Erosion is the process by which natural forces move weathered rock & soil from one place to another. 2

What is the material moved by erosion called? sediment Sediment may include pieces of rock or soil or the remains of plants or animals 3

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. ) 4

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. 5

Mass movement * happens when gravity moves sediment downhill. * can be rapid or slow and is caused by gravity. 6

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. 7

Landslides http: //en. wikipedia. org/wiki/Landslide h ttp: //carletong. wordpress. com/2009/04/27/paybacksamother/ 8

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. 9

Mudflows http: //cache. virtualtourist. com/1827048 -City_of_Plymouth_destroyed_by_Mud_Flows-Montserrat. jpg 10

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 11

Slump Cartersville, Georgia 12

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 H 2 O in cracked layers of rock beneath the soil 13

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/geo 101/masswasting. html&usg=__NXT 2 v. Qd 6 NNla. Yppssy 5 Jkhm. Qt. O 8=&h=357&w=300&sz=33&hl=en&start=7&um=1&tbnid=T 5 Wr. N 7 Z S 1 oq. Fe. M: &tbnh=121&tbnw=102&prev=/images%3 Fq%3 Dcreep%2 Bmass%2 Bmovement%26 hl%3 Den%26 sa%3 DN%26 um%3 D 1 14