Chapter C1: The Changing Earth

1. Chapter C1: The Changing Earth

2. Lesson 1: What are the Earth’s layers? Lesson 2: How does the Earth’s crust move? Lesson 3: What changes the Earth’s surface? Lesson 4: How do rocks reveal changes on the Earth?

3. Lesson 3: What changes the Earth’s surface? Change is good. . . • The surface of the Earth is constantly changing. • Weathering • Erosion • Deposition

4. Air Ice Chemicals Water Living things Lesson 3: What changes the Earth’s surface? Weathering. . . • The process that breaks down and changes rocks • Happens slowly

5. Lesson 3: What changes the Earth’s surface? Two types of weathering. . . • Physical Weathering • Rocks are broken apart. • Size and shape can change. • What they are made of does not change. Water gets into cracks in rocks, freezes, expands, and creates larger cracks.

6. Seeds and roots can find their way into cracks in rocks too. As the plant grows, the cracks become larger. Eventually, the rock splits.

7. The result of acid rain Lesson 3: What changes the Earth’s surface? Two types of weathering. . . • Chemical Weathering • Changes what rocks are made of • A chemical change Pollution often creates chemical weathering because polluted air and water contain chemicals that can make changes in rocks.

8. Chemical weathering creates caves like this one. Water joins with chemicals as it drains down through the soil. It changes the rock into a substance that dissolves and changes shape.

9. Air Ice Water Lesson 3: What changes the Earth’s surface? Erosion. . . • The process of moving weathered rock and soil • Takes place after weathering (obviously) • Happens quicker than weathering

10. Lesson 3: What changes the Earth’s surface? Erosion by water. . . • Flowing water is the main cause of erosion. • Moving water moves soil and rock particles to new places.

11. Waves crashing onto the shore quickly carry away sand and small rocks.

12. Melbourne, Australia 1983 Lesson 3: What changes the Earth’s surface? Erosion by wind. . . • Strong winds carry sand and soil particles.

13. Wind erosion can be a major problem during a drought when there is a great deal of dry, loose soil. The loss of soil can make farmland less fertile and useful.

14. Air Water Lesson 3: What changes the Earth’s surface? Deposition. . . • The dropping of materials moved by erosion • Can make the land better • Can create new land

15. Lesson 3: What changes the Earth’s surface? When a river floods. . . • It spreads out and slows down. • The soil and rock particles that were being carried along settle to the bottom and are left behind when the flood ends. • This deposited soil often makes great farmland.

16. Lesson 3: What changes the Earth’s surface? When a river enters the sea. . . • It spreads out and slows down. • The soil and rock particles are dropped in a fan-shaped area. • This material piles up and eventually forms new land called a “delta”. • Delta soil makes good farmland.

17. Nile River Delta Egypt These deltas will continue to grow as more and more soil, sand, and rock particles are deposited. Mississippi River Delta

18. Lesson 3: What changes the Earth’s surface? When waves reach the shore. . . • They slow down. • Sand carried by the waves is dropped, and new land is formed.

19. Lesson 3: What changes the Earth’s surface? When the wind blows. . . • It picks up sand, dust, dirt, and rock particles. • These get dropped when the wind slows down, or reaches an obstacle like a wall or a plant. • These dropped particles pile up to create sand dunes.

20. Any Questions?