1. Weathering, Erosion & Soil

2. External Forces that Shape Earth: Weathering Weathering: processes that change the characteristics of rock Creates sediment, or small pieces of rock (mud, sand, silt) Sandstone hills on the Utah-Arizona border

3. Types of Weathering Mechanical Changes SIZE or SHAPE Ex. Rocks splitting due to ice or tree roots Chemical Changes COMPOSITION Ex. Iron rusting, damage caused by acid rain

4. External Forces: Erosion Material is moved by wind, water, ice or gravity Reshapes landforms, coastal regions and rivers

5. Water Erosion Can be vertical or horizontal- streams can become deeper & wider Creates V-shaped valleys When a river empties into an ocean, it deposits sediment in a fan-like landform called a delta Examples: waves changing the coastline, Grand Canyon Nile River Delta

6. Wind Erosion Dust storms can carry 6,000 tons of sediment per cubic mile of air May produce new landforms Loess- wind blown silt & clay sediment that becomes fertile soil Arizona

7. Glacier: large, long-lasting mass of ice that moves due to gravity

8. Glacial Erosion Glaciation is the changing of landforms due to glaciers Creates U- shaped valleys

9. Rocks left behind by a glacier may form a ridge or hill called a moraine

10. Building Soil Weathering & erosion help form soil Soil: mixture of weathered rock, organic matter (humus), air and water Soils and climate determine what types of vegetation can grow in a location