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. Form when magma breaks through the earth’s crust
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