Changes Within the Earth

1. Changes Within the Earth Chapter 1 Section 2

2. GEOGRAPHY – the study of the earth’s physical structure and history • Physical Characteristics • The Earth’s Layers • Core – center (inner/outer) • Mantle – mostly solid • Crust – rocky surface layer • Natural forces interact with the earth’s crust, creating landforms, or natural features, found on the earths surface

3. Land, Air, and Water • Geographers often talk of the different elements of the earth’s natural environment as a set of related “spheres” dominated by different physical forms • Lithosphere – layer of soil, land, rock, landforms • Atmosphere – layer of air, water, and other substances above the surface • Hydrosphere – consists of water, oceans, lakes and rivers • Biosphere – the world of plants, animals, and other living things that occupy the land and water • 70% water • Continents – large landmasses in the oceans

4. Landforms are commonly classified according to differences in relief – the difference in elevations between the highest and lowest points • Major landforms – mountains, hills, plateaus, and plains

5. Physical Processes – “What forces shaped the landforms here?” • 1st – internal forces that originated in the earth’s interior • Volcanism • Form when magma breaks through the earth’s crust • On the surface, molten rock is called lava

6. Movement in the Crust • Bending and buckling breaks the earth’s crust • Results in a fold • Hardness of rock and strength of movement determines whether a fault or fold

7. Understanding the Past • Plate Tectonics – theory states the earth’s outer shell is not one solid sheet of rock

8. Continental Drift • Continental drift theory – Pangaea • One large continent that broke apart

9. Seafloor Spreading • Using sonar, scientists began to map the floor of the Atlantic Ocean, discovering that it was not flat • Youngest rock was found nearest underwater ridge system

10. Plate Movement/Meeting • Convection - a circular movement caused when a material is heated, expands and rises, then cools and falls • Subduction – when a denser plate slides beneath the other, an arc of volcanic islands may form along the plate boundary • When two oceanic plates collide, neither slides • Buckling, bending, folding

11. Expanding Volcanoes • Ring of Fire – circle of volcanoes surrounding the Pacific Ocean

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

13. Weathering • - the breakdown of rock at or near the earth’s surface into smaller pieces • Physical/Mechanical Weathering – when rock is actually broken or weakened physically • Freezing water • Frost wedging • Seeds taking root in cracks of rock

15. Chemical Weathering – altering a rock’s chemical makeup by changing the minerals that form the rock or combining them with new chemical elements • Water and carbon dioxide • Moisture • Acid Rain – chemicals in polluted air combine with water vapor and fall back to earth

16. Erosion • - movement of weathered material such as gravel, soil, and sand • Water – largest canyons and deepest valleys created by moving water • Sediment – small particles of soil, sand, and gravel • Wind – 2nd major cause • Loess – windblown deposits of mineral-rich dust and silt • Sandstorms

17. Glaciers • - huge, slow-moving sheets of ice • Moraines – ridge like piles of rocks and debris