1. Chapter 1 Section 3 Changes on the Earth’s Surface

2. Weathering The breakdown of rock at or near the earth’s surface into smaller and smaller pieces 1. Mechanical 2. Chemical

3. Mechanical Weathering Occurs when rock is actually broken or weakened physically 1. Frost Wedging- water freezes to ice in a crack in the rock 2. Seeds take root in cracks in rocks

4. Chemical Weathering Alters a rock’s chemical makeup by changing the minerals that form the rock or combining them with new chemical elements Can change one kind of rock into a completely different kind

5. Acid Rain Chemicals in the polluted air combine with water vapor and fall back to earth as acid rain

6. Erosion The movement of weathered materials such as gravel, soil, and sand 1. Water 2. Wind 3. Glaciers

7. Water Moving water is the greatest cause of erosion Sediment- small particles of soil, sand, and gravel- act as sandpaper Rivers wash away soil and rocks and change the landforms Ocean waves wash away coastline

8. Wind 2nd major cause of erosion It blows the soil away from farmlands Loess- extremely porous soil that absorbs and holds great amounts of water Sandstorms effect desert areas

9. Glaciers Huge, slow moving sheets of ice Carve a U-shaped path in the earth as it slowly moves