1. Chapter 8

3.  Erosion is the process that wears away surface materials and moves the sediments from one place to another.

4.  Don’t let Gravity get you Down!!!  Gravity is the force of attraction that pulls all objects toward the Earth’s center.

5.  Water and wind erode materials only when they have enough energy of motion to do work. ◦ Example: Strong winds can move dust sediments.  Glacial erosion is another agent of erosion. ◦ Glacial erosion slowly moves sediments that is trapped in solid ice. ◦ As the ice melts, sediment is deposited, or dropped. ◦ Sometimes sediment is carried further by moving meltwater.

6.  Deposition is the dropping of sediments that occurs when an agent of erosion, such as gravity, a glacier, wind, or water loses its energy and can no longer carry its load.

7.  Mass Movement is any type of erosion that happens as gravity moves materials downslope.  Mass movement can be slow or quick.  The greater an object mass is, the greater its gravitational force is.  Gravity is a major force of erosion and deposition.  Common mass movements include slump, creep, rockfalls, rock slides, and mudflows.

8.  When a mass of a material slips down along a curved surface, the mass movement is called slump. ◦ Usually occurs:  Steep hills  Movement of water down hill  Strong rock layers laying on weaker rock layers

9.  A creep is a type of mass movement in which sediments move down-slope very slowly.  It is common in areas of freezing and thawing, and can cause walls trees, to lean downhill.

10.  Signs along mountainous roadways warn people of a mass movement called a rockfall.  Rockfalls occur when blocks of rock break loose from a steep slope and tumble through the air.  As the rock fall, they hit other rocks and break them loose.  Rock slides occur when layers of rock, usually steep layers, slip downslope suddenly.

11.  A mudflow is a thick mixture of sediment and water flowing down a slope.  They often occur: ◦ When vegetation has been removed by a fire ◦ Thick layers of loose sediment ◦ Areas of heavy rainfall  Why might mudflows be more dangerous than flood waters?

12.  All types of mass movement occur more often after heavy rain.