Chapter 7 Erosion

What is Erosion and Deposition?

• Erosion – A process that moves the sediments from one location to another, usually by gravity, glaciers, wind, or water.

• Deposition – Final step in an erosional process, sediments are dropped as their energy of motion decreases.

Erosion by Gravity

• Mass Movement – when gravity alone causes loose material to move downslope.

– Slump – one large mass of loose material moves downhill leaving a curved scar.

– Creep – sediments move downhill slowly, causing posts and trees to lean.

Glaciers

• Glaciers are a mass of snow and ice that move slowly downhill due to its weight.

Glacial Erosion

• Plucking – rock fragments are loosened, broken off, and carried away by the freezing of water in rock cracks.

Wind Erosion

• Deflation – removes loose, fine-grained sediments (silt & clay), and leaves behind coarser material.

• Abrasion – wearing/scraping away by sand grains or other particles striking other sand grains and rocks, breaking off small fragments.

Other types of wind erosion

• Sand Storm • Dust Storm