Merrill Earth Science

Chapter 6: Erosion and Deposition

6-1 Gravity

Erosion- is the process that moves weathered sediments from one location to another.

4 major types or agents:

1. Gravity

2. Running water

3. Glaciers

4. Wind

Deposition- the dropping or depositing their load of sediments when their motion decreases.

Gravity: causes materials to move downslope at a variety of speeds.

Slump: is a type of mass movement that takes place on steep slopes. It occurs because the material under the slumped material weakens.

Creep: as the ground freezes, small sediments are pushed up by the expanding water in the soil. Then, when the soil thaws, the sediments fall downslope, often less than a millimeter at a time.

Rockslides: Page 145

Mudflows: occur in dry areas after a heavy rainstorm(s). Steep slopes.

6-2 Running Water:

Water erodes more sediments than any other agent of erosion.

Rill Erosion- begins when a small stream forms during a heavy rain.

Rills may evolve into gullies- thus creating gully erosion.

Sheet erosion- happens when this rainwater flows into lower elevations, carrying sediments with it.

Types of Deposits:

Alluvial Fan: shaped like a triangle, occurs when a stream slows down rapidly due to the leveling of the slope.

Deltas: an area of deposit where streams or rivers flow into lakes or oceans.

6-4 Glaciers

Glaciers: a slowly moving mass of snow-moves downhill. Movement is what separates glaciers from snowfields.

Continental Glaciers: very large cover the earth’s polar regions.

Valley or Mountain Glaciers: smaller, found in mountain regions where the climate is temperate or colder with a high annual snowfall.

Glacial Erosion:

Most powerful type of erosion.

Plucking- movement of rocks fragments by the ice itself. See page 157

Glacial Deposition: Page 159

Moraines:

Till:

Outwash Plain:

6-5 Wind

Wind erodes in 2 ways: by deflation and by abrasion.

Deflation: wind picking up small particles.

Abrasion: a type of sandblasting. The moving air with rock particles acts like sandpaper.

Wind Deposition:

Loess:

Dunes: