1. Internal Forces Shaping the Earth Updated 8/21/12

4. Earth’s Structure:
1) Core: solid metallic center of the earth.
2) Mantle: miles thick
3) Crust: thin layer of rock at the surface

5. PANGAEA

6. Pangaea: 200 million years ago there was 1 super continent.
Continental Drift: Theory that supercontinent separated and drifted apart.

7. Evidence of Pangaea Fossils-distribution of ancient plants and animals
Paleoclimatology-sedimentary rocks indicate climate and latitude of original placement
Rock magnetism-rocks, especially volcanic rocks, preserve a record of the orientation of the earth’s magnetic field
Sea floor spreading-formation of the Mid-Atlantic Ridge

8. Fossil Support

10. Plate Movement
Tectonic Plates are enormous pieces of the earth’s lithosphere that are slowly moving
Plates move along 3 boundaries:
Divergent: plates move apart, spreading horizontally
Convergent: Plates collide, causing one plate to go underneath or both edges crumble
Transform: Plates slide past one another

11. Plate Absolute Velocity (cm/yr)*
Antarctic ~2.05
African ~2.15
Arabian ~4.65
Caribbean ~2.45
Cocos ~8.55
Eurasian ~0.95
Indian ~6.00
Nazca ~7.55
North American ~1.15
Pacific ~8.10
Philippine ~6.35
South American ~1.45

12. EXAMPLES
Divergent: between Saudi Arabia and Egypt: plate movement is causing the Red Sea to become wider than ever before.
Convergent: Himalayas are caused by the Indian plate crashing into the Asian plate.
Transform: San Andres Fault, California.

13. Divergent Plate Boundary

14. Convergent Plate Boundary

15. Transform Plate Boundary

16. Plate Boundaries

17. EARTHQUAKES
Earthquakes: as plates grind or slip past each other at a fault, the earth shakes or trembles.
Seismograph: Measures size of waves created by earthquake.
Epicenter: -Location on the earth where earthquake begins.

18. Richter Scale: C. E. Ritchie developed a scale to measure amount of energy.
Tsunami: Earthquake below the ocean and can cause a giant wave.

19. Volcano: An opening in the earth’s crust where Magma and gases escape
Volcano: An opening in the earth’s crust where Magma and gases escape. Most are found near the tectonic plate boundaries.
Magma that reaches the earth’s surface is called lava.

20. Ring of Fire: A zone around the rim of the Pacific Ocean where most active volcanoes are found.