4) Waves

the force of waves striking the shoreline break rock into smaller pieces (abrasion). The smaller pieces are then carried away by the waves.

1890 (Watch the lighthouse.)

1910

1920

1970

1990

Features formed from wave erosion:

Sea arches

Sea cliffs

Sea stack

Sea caves

Human Effects on Erosion

Clear cutting – clearing all vegetation; deforestation can increase soil erosion

Human Effects on Erosion

Construction grading

Human Effects on Erosion

Farming (example – if cattle are over grazing, the soil will be eroded more quickly by wind and water)

Human Effects on Erosion

Strip mining – soil and rock overlying mineral or rock deposits are removed

Reducing Erosion

Planting vegetation – ground cover, shrubs, trees; Planting trees on a flat, open plain helps to protect soil from erosion due to wind.

Reducing Erosion

Installing drainage pipes

Reducing Erosion

Silt fencing

Reducing Erosion

Retaining walls

Reducing Erosion

Terracing – a sloped plane that has been cut into a series of flat surfaces or platforms that look like steps

Tying in Social Studies

You will learn about the Incan Empire of South America in your Social Studies class.

One of their greatest achievements was the construction of a “hidden city” high up in the South American Andes mountains called Machu Picchu. The Inca were famous for their use of terrace farming!

In order to survive, the Inca had to figure out a way to farm on the steep mountain sides on which they lived.

Terrace Farming

Reducing Erosion

Contour plowing – rows that act as a series of dams, not river

Reducing Erosion

Crop rotation

Deposition

process of dumping or putting down material eroded away from another place, (Example – If you mixed a sample of soil with water in a jar and let it settle for 24 hours, it would show the deposition of sediment in a lake bed.)

Deposition

Deposition of sediments at the mouth of a river can create a landform such as a delta, a triangle-shaped deposit of sand, clay, or silt. When the velocity of a river changes as it enters a quiet body of water, sediment is deposited and forms a delta.

Deposition by running water– sediments are building up along the side of the river.

Deposition by glaciers– As glaciers melt, large rocks that were frozen in the glacier can be deposited in a completely different area than where they originated.

Huge boulders can be found in NYC central park. The large rocks were deposited there by a retreating glacier during the last ice age!

Large boulders transported great distances by glaciers are called erratics. Yeager Rock, a 400 ton erratic on the Waterville Plateau, Washington.

Deposition by wind- sand dunes

Deposition by waves

Deposition by Mass Movement

Scientifically called Talus, otherwise known as a BIG PILE OF ROCKS AND MUD…

Make it easy:

Weathering- breaking down (making sediments)

Erosion- carrying away (moving those sediments)

Deposition- dump and stack (where the sediments settle)