Erosion And Deposition Chapter 6 Reshaping Earths Surface

Erosion And Deposition Chapter 6

Reshaping Earth’s Surface • Constructive processes build up features on the Earth’s surface. • Destructive processes tear down features on the Earth’s surface.

Continual Process Change • Weathering is the breakdown of rock. • Erosion is the removal of weathered material from one location to another. • Deposition is laying down sediments with gravity, running water, wind and glaciers. • High energy- sediment is transported quickly. • Low energy- small sediments get deposited.

INTERPRETING LANDFORMS • Features such as structure, elevation and rock exposure give clues about how a landforms. • Tall, jagged structures are usually formed by erosion. • Low or flat landforms are often formed by deposition. • At the base of a mountain slope a stream will deposit an apron of sediment called an alluvial fan. • Deposition in a riverbed occurs where the speed of the water decreases. • As glaciers melt, they can create deposits called eskers and moraines.

Shaping the land with water and wind • Destructive processes such as weathering and erosion produce tall jagged landforms. • Constructive processes such as deposition produce flat, low lying landforms. • Water and wind are important agents of weathering, erosion and deposition.

Water, Erosion and Depostion • The speed of water and the depositional environment often affect the shape of the land. • The erosion produced by the stream depend on the streams energy. • Currents and waves constantly produce coastal erosion.

• Acidic water carves out spaces in underground rock, causing caves. • Structures in cave that form by deposition are called stalactites and stalagmites. • Flowing water deposits sediment as the water slows. • A delta is a large deposit of sediment that forms where a stream enters a large body of water.

• Damage caused by water erosion can be affected by the way people use the land. • To reduce beach erosion people build retaining walls, or groins, which trap sediment and reduce erosive effects of longshore currents. • A floodplain is a wide, flat area next to a river that usually remains dry. • A levee- a long, low ridge of soil along a river- can decrease flooding on a floodplain.

Wind erosion and deposition • Abrasion is the grinding away of rock or other surfaces as particles carried by wind, water or ice scrape against them. • A dune is a pile of wind blown sand. • Loess is a crumbly, windblown of silt and clay. • People can slow the affects of wind erosion by planting rows of trees at the edge of farm fields to slow wind.

Mass Wasting • Mass wasting is the downhill movement of a large mass of rocks or soil because of gravity. • Mass wasting usually occurs on the side of a hill when the soil is soaked with rainwater. • Thick vegetation can prevent mass wasting. • A landslide is the rapid downhill movement of soil. Loose rocks, and boulders. • Erosion due to mass wasting continues as long as the force of gravity is greater than other forces holding the rocks and soil in place. • Building on a steep slope, removing vegetation and heavy machinery can increase the chances of mass wasting

Glacial Erosion and Depostion • A glacier is a large mass of ice that formed on land moves slowly across earth’s surface. • Glaciers cause erosion as they move carving grooves in underlying surfaces of Earth. Glacial erosions cause sharp ridges called aretes and U-shaped and hanging valleys. • Glaciers deposit material when they melt. • Till is a mixture of sediment deposited by glaciers. • A mound or ridge of sediment deposited by a glacier is a moraine.

• Global warming is the gradual increase in the Earth’s average temperature. • Human activities contribute to global warming. • Because of global warming, glaciers have been melting, which leads to a rise in sea level.