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 ErosionIn nature, sediment can be moved

by:Gravity (Mass Movement)Water (Rivers, Streams, Groundwater)GlaciersWavesWind

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 http://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, Georgia12

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 soil13

Creep

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

Bent tree trunk illustrating creep. National Zoo, Rock Creek Park, Washington, D.C.

14