1. Changes on the Earth Weathering and erosion

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

3. Mechanical weathering Is when rock is actually broken or weakened physically –Produces stones, pebbles, sand, silt, dust –Primary process of soil building Caused by water and seeds

4. Frost wedging When water freezes in the cracks of a rock, it expands and widens the crack eventually causing the rock to split

5. Seed wedging When a seed takes root in the crack of a rock it also widens the crack You’ve probably seen a driveway broken by a tree root

6. Chemical weathering Alters a rock’s chemical makeup by changing the minerals that form the rock or combining them with new chemical elements Acid rain is a form of chemical weathering

7. Erosion Is the movement of weathered material such as gravel, soil, and sand 3 main causes –Water –Wind –glaciers

8. Water Is the main cause of erosion Forms canyons and valleys Rocks and soil carried away are deposited somewhere else creating a new landform

9. Wind 2 nd leading cause; especially where there is little water and few plants to hold soil in place sandstorms

10. Glaciers Huge slow moving sheets of ice, slide forward because of their weight