1 Plate Tectonic Theory 1. What are these things called plates? 2. What do plates do? 3. What is the evidence for the existence of plates? 4. How do plates move?

2 What is a Plate? A plate is a large section of crust that shifts position over time. There are typically 7 major plates and several other minor plates The major plates are the north American, South American, Eurasian, Arctic, African, Australian, and Pacific plates.

Plates

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5 What do colliding plates do? They form convergent boundaries and produce mountains, volcanoes, and earthquakes. They pile crust or get rid of it.

6 What do separating plates do? They form divergent boundaries to produce earthquakes, rift valleys, and a few volcanoes. They form new crust.

7 What do sliding plates do? They form transform boundaries that produce earthquakes, They generally do not form new crust or destroy it.

8 Boundary Types Boundaries are the joints between two or more pieces of the crust Divergent Boundaries: Crusts moving away from one another Convergent Boundaries: Crusts moving toward one another Transform Boundaries: Crusts sliding alongside one another

9 How do plates move?

10 Theory of Plate Tectonics Like a broken eggshell States that Earth’s crust is moving around not just the continents Crust is the outermost layer of Earth’s body and is fragmented Crust floats on molten rock Molten rock below upper crust has heat currents that push crustal rock (convection currents) Slab pull and ridge push aid in movement of oceanic plates and some continental plates. Theory is generally accepted