Unit 4.1 ~ Plate Tectonics

• The core is radioactive and hot which drives convection.

  

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• Convection occurs in the upper mantle in a slow, creeping motion. It breaks the lithosphere into plates and moves them

Oceanic - Continental

• Oceanic crust is denser than continental and subducts below

• Subduction creates trenches and cracks

• Magma seeps through cracks and creates volcanoes

• Causes earthquakes and volcanoes

  

Oceanic - Oceanic

• Both crusts are basalt

• Older crust is denser due to more sediments

• Creates volcanic island arcs (Japan and Aleutian Islands in Alaska)

• Causes tsunamis and earthquakes

  

Continental-Continental

• Both crusts are granite

• Same density so push up

• Little subduction

• Happens in

  • Himalaya Mountains between India and Nepal

  

Divergent

• Crusts pull apart and magma rises to fill gap

• Magma hardens when cooled by ocean water

• Creates underwater mountain ranges

• Mid-ocean ridges in

  • Iceland, African Rift Valley

  

Transform

• 2 plates slip past earth other 

• Some called strike-slip faults

• San Andreas fault in California between Pacific and North American plates

  

Hot Spot Volcanoes

• Occur in the middle of plates where crust cracks and magma seeps up

• Hawaiian Islands on Pacific Plate

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• Yellowstone hot spot on N. Amer. plate - flat volcano

  

  Rock Cycle

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