Ms. Leung C1 Review

Changing of the Earth’s surface by breaking it down 2 processes- WEATHERING- the breaking down of the materials of Earth’s crust into smaller pieces. EROSION- the picking up and carrying away the pieces.

2 types of weathering Physical Weathering Chemical Weathering

Physical Weathering- WATER Weathering happens when the crust is exposed to water, air, and changes in temperature. Water - water can dissolve minerals right out of the crust. - Moving water can make pieces of rock bang into each other. - Small chips can break off the surface of the rock- this causes the rock to get smaller and rounder. - The churning (harsh movement) of water streams can wear down big pieces of rock into small round pebbles.

Physical weathering- Wind Wind (moving air) Blows sand and other broken bits of rock over the Earth’s surface (This can also wear away rock)

Physical weathering- Temperature Temperature drops low enough for water to freeze- when the water freezes is expands- gets bigger- take up more spaces. When water freezing in cracks of rocks the force of the expanding water is great enough to split the rock apart. Change in temperature can also cause a rock to expand and contract. (only certain types of rocks) This will eventually cause the rock to break down.

Chemical Weathering Air contains gases that react chemically to form new substances. -Oxygen in the air reacts with iron to form rust - Carbon Dioxide and Sulfur Dioxide in the air react with rain to form acids (eat away limestone rock)

Erosion Carrying away of pieces of weather rock by gravity Think about it over enough time, erosion can carry away a boulder, a hill, or even a mountain. The most important factor of erosion is WATER.

From the moment a drop of water hits the ground, it erodes the land. Once water reaches the ground, it will begin to move downhill. The water moving down hill will pick up things and carry them along in its journey. The faster the water is moving, the bigger the piece of rocks it can move.

Wind and ICE Erosion Wind- picks up small particles and moves them ICE- freezes onto the rock and scrapes away the surfaces. Ice can also tear rocks from the ground as it moves.

Let’s think about what happens to moving water It is eventually going to slow down when it flows into a large body of water (OCEAN or lake) When the water stops moving it also stops carrying the eroded material- these pieces are just dropped. The dropped pieces of eroded material is called deposition. Deposition-The dropping off of bits of eroded rock.