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 * Dynamic Earth**

Earth's crust is made of multiple different tectonic plates, major, and minor plates. Some of the major plates include North American, African, Antarctic, and Eurasian plates. Some minor, but still important plates include Juan de Fuca, in the Pacific Northwest (which is responsible for many volcanoes), Scotia Plate, and Coco's Plate. Earth's plates started as one land mass, called Pangaea.



1. __**Convergent Boundaries**__ - Two plates are moving towards each other. The plates push together with great force, sometimes, a plate sliding under the other. Subduction zones are located here. In the ocean, earthquakes cause large tsunamis, such as the tsunami in New Orleans. On continental plates, the plates collide, creating mountains such as the Himalayas, where India slid into Europe.



2. __**Divergent Boundaries**__ - Two plates move away from each other (spreading plates). Once the plates have spread, in the ocean, magma fills the spaces and hardens. This is now called a mid-ocean ridge. On land, rift valleys occur when the plates spread. Volcanoes become very active now.



3. __**Transform Boundaries**__ - Plates grind against each other, back and forth. This back and forth motion forms faults, or cracks and fractures in the Earth's crust. Many earthquakes occur. The San Andreas Fault in California is a strike-slip fault, a fault where the rocks on opposite sides of the fault plane move horizontally. Here, there is no footwall or hanging wall (see examples). The 1857 Fort Tejon earthquake, 1906 San Francisco earthquake and fire, and the 1989 Loma Prieta earthquake (all near San Andreas Fault



Citations: "Slip, Slide, and Collide." //Interactives Dynamic Earth//. Annenberg Media, 1997. Web. 9 Nov. 2009. . "Plate Tectonics." //National Geographic//. National Geographic Society, 1996. Web. 9 Nov. 2009. .