Of water in cracked layers of rock beneath the soil.

[Pages:3]Name:__________________________ Mass movements Worksheet Erosion is the process by which natural forces move weathered rock and soil from one place to another. Gravity, running water, glaciers, waves and wind all cause erosion. The material moved by erosion is sediment. When the agents of erosion lay down sediment, deposition occurs. Deposition changed the shape of the land. Weathering, erosion and deposition act together in a cycle that wear down and builds up the earth's surface. Erosion and deposition are at work everywhere on Earth. Sometimes, they work slowly. At other times, they work more quickly. Erosion and deposition are never-ending. Gravity pulls everything toward the center of Earth. Gravity is the force that pulls rock and soil down slopes. Gravity causes mass movement, any one of several processes that move sediment downhill. Mass movement can be rapid or slow. The different types of mass movement include landslides, mudflow, slump, and creep. The most destructive type of mass movement is a landslide, which occurs when rock and soil slide quickly down a steep slope. Some landslides may contain huge masses of rock, while others may contain only a small amount of rock and soil. A mudflow is the rapid movement of a mixture of water, rock, and soil. The amount of water in a mudflow can be as high as 60 percent. Mudflows often occur after heavy rains in a normally dry area. In clay soils with high water content, mudflows may occur even on very gentle slopes. An earthquake can trigger both mudflows and landslides. In the type of mass movement known as slump, a mass of rock and soil suddenly slips down in one large mass. It looks as if someone pulled the bottom out from under part of the slope. Slump often occurs when water soaks the base of a mass of soil that is rich in clay. Creep is the very slow downhill movement of rock and soil. It occurs most often on gentle slopes. Creep is so slow that you can barely notice it, but you can see its effects in objects such as telephone poles, gravestones, and fence posts. Creep may tilt these objects at unusual angles. Creep often results from the freezing and thawing of water in

cracked layers of rock beneath the soil.

1. What causes mass movements? ___________________________________________________________________

2. What are four types of mass movement? _________________________________________________________

3. What is the difference between a mudflow and a landslide? _____________________________________________

______________________________________________________________________________________________

4. What are four causes of erosion? __________________________________________________________________

5. _______Which type of mass movement is likely to result in considerable property damage, but rarely causes loss of

life?

A. debris avalanche b. rock fall

c. mudflow

d. creep

6. _____You are driving along a curvy mountain road, with a rocky vertical cliff on one side and a steep, rocky drop off on the other side. A yellow sign warns of the possibility of a mass movement that could affect your driving. Under the circumstances, what type of mass movement is most likely? a. creep b. landslide c. mudflow d. avalanche

Identify each of the examples below by writing landslide, mudflow, slump, or creep. 7. ________________________Watery clay soil slides down a mountain. 8. ________________________A telephone poll leans downhill. 9. ________________________Rock at the top of a cliff suddenly falls. 10. ________________________As you step on the mountain path, bits of rock and soil fall downhill. 11. ________________________After a heavy rainfall, soil on a desert hill slides to the bottom. 12. ________________________After many years, a gravestone on a hillside falls over. 13. ________________________Rock and soil suddenly slip due to water soaking into the base of the soil.

14. ________________________, ______________________During an earthquake, rock and soil move down a slope.

Fill in the blank 15. The agents of erosion lay down sediment in new locations in a process called ________________________. 16. The material moved by erosion is called __________________________. 17. The process by which natural forces move weathered rock and soil from one place to another is called

___________________________. 18. _____________________________ are several processes, caused by gravity, that move sediment downhill. 19. A ____________ has happened when previously straight objects are seen as tilted. 20. Weathering, erosion and deposition work together as a ___________ that wears down and builds up the earth

surface.

True or False

21. T or F - The force of gravity is responsible for mass movements. 22. T or F ? Once a rock is weathered, it is not susceptible to mass movement. 23. T or F - Mass movement that are flows occur only in fine sediments that are water saturated. 24. T or F ? Landslide, avalanches, and mudflows are some of the most rapid types of mass movements. 25. T or F ? All mass movements happen very quickly. 26. T or F ? The most destructive mass movement is a rockfall. 27. T or F ? Mudflows are not as likely on gentle slopes. 28. T or F ? Erosion and deposition work independently of each other. 29. T or F ? When heavy rains fall on normally dry areas, the land is less likely to move because it has more room to

soak in the water. 30. T or F ? Earthquakes can trigger a creep.

Name the type of mass movement shown in the pictures below. Landslide, Avalanche, Creep, Slump, Mudflow, Rockfall

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