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Plate Tectonics Chapter 3: 2 nd Half. Plate Tectonics . Incorporates the ideas of continental drift and seafloor spreading in a unified model. 7 Major Plates. The Plates are Outlined by the Major Earthquake/Volcanic Belts of the World. Boundary Types. Divergent Boundary.
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Plate Tectonics Chapter 3: 2nd Half
Plate Tectonics • Incorporates the ideas of continental drift and seafloor spreading in a unified model.
The Plates are Outlined by the Major Earthquake/Volcanic Belts of the World
Divergent Boundary • Plates move apart • Ocean basins are created that break apart continental lithosphere • Broke up Pangaea • Mantle upwelling heats the base of the lithosphere, thinning it, causing it to dome upward • Creates faulting and volcanic activity • Rift zone: lithosphere splits, allowing new crustal material to come in to the crack or rift • Made up of 4 layers of the oceanic lithosphere • Divergent boundaries can have transform fault motion
Transform Fault/Boundaries • 2 plates that simply past one another • The San Andreas Fault in Ca. is an example of a transform fault. The Pacific Plate is moving northwest and the North American plate is moving west. • The movement is not uniform. Roughly, every 70 years there is major movement. Last earthquake was 1989.
Convergent Boundary • Plates move toward each other • Caused by subduction of one plate into the mantle beneath another plate • Often occurs along an ocean trench which results in volcanoes and earthquakes • Continental/Ocean boundaries: ocean plate moves downwards • Ocean/Ocean boundaries: oldest, more dense plate moves downwards • Continental/ Continental boundary: one plate does notsubduct under the other plate. Plates buckle upward
Continental/Ocean Boundary • Active volcanoes along this boundary • Explosive eruptions • Includes the Cascade Range of the Pacific Northwest, including Mount St. Helens
Ocean/Ocean Boundary • Produces a line of active volcanoes on the ocean floor of the overriding plate • The volcanoes may grow large enough to reach the surface and form a island arc. • Island arcs most commonly found in the Pacific Ocean • Deep earthquake activity is associated with this boundary
Continental/Continental Boundary • Result of the closing of an ocean basin • Along the edges of the 2 colliding plates, the crust buckles, fractures, and thickens. • Produces great mountain ranges. One classic example is the Alps and Himalayas. • India collided with Asia to produce the Himalayan mountains and they are still being created today.
India Hitting Asia Forming The Alps and The Himalayan Mountains
Old Faithful Yellowstone National Park Old Faithful Geyser, Yellowstone National Park
