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when two plates move apart. sea floor is spreading. creates mid ocean ridge, rift valley
a plate boundary where two plates move past each other in opposite directions. earthquake activity
a plate boundary where two plates move toward each other. ocean to ocean. deep sea trenches, subduction. ocean to continent, subduction. continent to continent, collision.
sea floor crust
in the process of sea-floor spreading, new ocean floor forms along earth's mid-ocean ridges, slowly moves outward across ocean basins, and finally sinks back into the mantle beneath deep-ocean trenches. made of basalt
The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick
what is the difference between passive and active
active-volcanoes are erupting
passive-dormant volcanoes, sediments
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