Plate Tectonics Explains: Mountains (Orogeny) Earthquakes Volcanoes

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1 Plate Tectonics Explains: Mountains (Orogeny) Earthquakes Volcanoes
Ocean Trenches

2 Plates Lithosphere is broken into pieces (plates).
New lithosphere is constantly: - being made (by volcanoes and ridges) - being lost (by subduction)

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4 Plate Tectonics Magma = liquid rock underground.
Lava = liquid rock on surface (becomes igneous rock).

5 Plate Boundaries (Edges)
Where plates meet other plates, three things can happen: Diverge – move apart Converge – come together Transform – move past each other

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7 Divergent Plates When plates move apart:
-- youngest rock where plates meet. -- usually under the ocean (mid-ocean ridges), but also on land (rift valleys).

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9 Divergent Plates Convection currents cause upwelling. Move 2.5 cm/yr
Mountains, Volcanoes, and Earthquakes

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11 Converging Plates When plates move toward each other.
Continental into Continental: -- plates have same density -- crumple and fold, making mountains.

12 Himalayas

13 Subduction Oceanic into Continental:
-- oceanic crust is denser than continental crust. -- so, it sinks under continental crust into mantle = subduction

14 Subduction

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17 Thermal Slab

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19 Subduction All subduction zones have: Volcanoes Ocean Trenches
Earthquakes Tsunamis

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21 Transform Plates When plates move past each other.
-- stress builds up, then releases suddenly, causing an earthquake. -- San Andreas Fault

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24 Hot Spots Some volcanoes form far from plate edges.
Hawaiian volcanoes are 4,000 km from a plate boundary. How do they form?

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29 Other Hot Spots Geothermal activity (hot springs, geysers, volcanoes) far from a plate boundary. Yellowstone, Iceland, Galapagos Islands

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