Wind Water Glacier

Weathering

• Weathering refers to physical and chemical processes that change the characteristics of rock on or near the earth’s surface.

• Weathering occurs slowly over many years and even centuries.

In what ways do you think this rock face has changed over time?

Sediment – a weathering process that creates smaller and smaller pieces of rock. Sediment is mostly identifiable as either mud, sand, or silt, which is very fine particles of rock.

Physical Weathering

• Processes that break rock into smaller pieces are referred to as Physical weathering.

• Physical weathering does not change the composition of the rock – only it’s size.

Sometimes ice crystals can form in the cracks of a rock, forming so much pressure, that they break the rock into smaller pieces.

Chemical weathering

• Occurs when a rock is changed into a new substance as a result of interaction between elements in the air or water and the minerals in the rock.

Erosion

• Erosion occurs when weathered material is moved by action of wind, water, ice, or gravity.

This canyon was cut by water.

This beach has been so eroded away by the ocean that this house will eventually slide off into the ocean.

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How does the wind effect these sand dunes?

Loess

• Wind blown silt and clay sediment that produces very fertile soil.

• In northern China the deposits are several hundred feet deep.

What looks like a road in this picture was actually created by a glacier sliding down through this mountain range.

Moraine – piles of rocks left behind after the glacier melts. They are usually found on the sides, down the center, or at the leading edge of a glacier.

Soil is the loose mixture of weathered rock and organic material.

Parent material – the chemical composition of the original rock before it decomposes.

Humus – the amount of organic material in the soil and the amount of air and water needed in the soil to make it fertile.

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• Rain, rivers, streams, and oceans are the most significant cause of erosion.

• Begins when springwater and rainwater flow off the land downhill into streams.

• As the water flows, it cuts into the land, wearing away soil and rock.