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C6 L3: How Do Weathering and Erosion Affect Rocks?
Terms in this set (11)
Weathering is the breaking down of rock on Earth's surface into smaller pieces. Weathering helps shape landforms. It also helps make soil.
Two types of weathering
1) One type of weathering PHYSICALLY BREAKS rocks into smaller pieces. 2) The other type of weather CHANGES THE CHEMICAL MAKEUP of rock. This softens and weakens the rock, helping water wear it away.
How are sinkholes formed?
Sinkholes are the result of weathering. They form when water slowly dissolves underground rock.
What causes most weathering?
Water causes most weathering. RUNNING WATER in rivers carries sediment. The sediment scrapes against itself and against rocks in the streambed as the water moves. Large ocean waves smash into the bottom of a cliff. The rock that the wave hits cracks and breaks. Rain enters cracks in rock and cement. If the water freezes into ice, it expands. The ice cracks and breaks rock around it.
Living things can cause weathering.
You have probably seen plants grow through cracks in rocks. The root wedges into the rocks, splitting the rock around them as they grow. Animals can cause weathering, too. When animals dig in soil, they move rocks closer to the Earth's surface. Then rainwater can reach them more easily.
Wind causes weathering.
Wind picks up bits of rock and soil and throws them against other rocks. This chips away the rock's surface bit by bit.
After weathering breaks down rock into sediment, EROSION takes over. Erosion is the process of MOVING SEDIMENT from one place to another.
Water in rivers can cause erosion.
Rivers carry sediment downstream. They drop it on their banks or at their mouths.
Ocean waves can cause erosion.
Ocean waves pick up sediment and leave it on the shore as sand.
Wind can cause erosion.
Wind erosion is most common in deserts. With few plants to hold sediment in place, wind picks it up easily. Wind stacks sand into huge mounds called sand dunes.
Glaciers are important causes of erosion.
As these giant sheets of ice move, they scrape the ground. They pick up rocks and soil. During the last Ice Age, glaciers eroded and helped shape the plains and other landforms we see today. As glaciers moved over land, they also formed lakes. When the glaciers melted, they left behind huge ridges of sediment and large amounts of water.