1. Plate Tectonics
A geological theory that states that pieces of Earth’s crust are in constant, slow motion, driven by convection currents in the mantle
The plates of the lithosphere float on the top of the asthenosphere
Convection currents rise in the asthenosphere and spread out beneath the lithosphere
Geologists believe this causes plate movement
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2. Convection Currents: The movement of a fluid, caused by differences in temperature, that transfers heat from one part of the fluid to another
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3. Plates are a section of the lithosphere that slowly moves, carrying pieces of continental and oceanic crust
As plates move, they collide, pull apart, or grind past each other producing spectacular changes in the earth’s surface.
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4. Crust is neither created nor destroyed
Transform Boundary
A plate boundary where two plates move past each other in opposite directions
Crust is neither created nor destroyed
Fault lines are usually created in which earthquakes happen
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5. Figure 1-13 Transform Motion
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6. Geology at a Glance Plate Boundaries (cont'd)
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7. Convergent Boundaries
A plate boundary where two plates move toward each other
Collisions can occur between:
oceanic crust and oceanic crust (subduction)
deep ocean trenches
oceanic crust and continental crust
volcanic eruptions
continental crust and continental crust
mountain ranges
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8. Geology at a Glance Plate Boundaries (cont'd)
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9. Figure 1-12a Continental Collision
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10. Figure 1-12b Continental Collision (cont'd)
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11. Figure 1-11 Plate Subduction
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12. A plate boundary where two plates move away from each other
Divergent Boundaries
A plate boundary where two plates move away from each other
Most divergent boundaries occur at the mid-ocean ridge
Divergent boundaries that occur on land are called rift valleys
Ocean Basins are usually the result of this type of movement
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13. Geology at a Glance Plate Boundaries (cont’d)
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14. Transform Convergent Divergent Summary of Boundaries
Plates slip past each other (grind)
Convergent
Plates come together (collide)
Divergent
Plates move apart (pull apart)
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15. Geology at a Glance Plate Boundaries

16. Major Plates Six major plates: Eurasian African Indo-Australian
Pacific
North American
South American
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