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Unit 4, Set 2 - Plate Tectonics

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mid-ocean ridge
chain of underwater mountains at the boundary between two diverging tectonic plates where new ocean floor is produced
seafloor spreading
the formation of new areas of oceanic crust due to magma rising at mid-ocean ridges and moving outward
subduction
process by which one tectonic plate moves under another tectonic plate and sinks into the mantle
tectonic plates
individual sections of the Earth's lithosphere that fit together in a way similar to a jigsaw puzzle, but are always moving very slowly, floating on the asthenosphere
convergent boundary
place where two tectonic plates move toward each other; associated with trenches, island arcs, and folded mountains
divergent boundary
place where two tectonic plates move apart; found primarily on the seafloor; associated with volcanic activity, earthquakes, and high heat flow
rift valley
long, narrow depression that forms when continental crust begins to separate at a divergent boundary
volcanic island arc
chain of volcanoes formed due to subduction of an oceanic plate under another oceanic plate or a continental plate under another continental plate
transform boundary
place where two tectonic plates slide horizontally past each other; characterized by long faults and shallow earthquakes
deep-sea trench
a deep valley along the ocean floor through which oceanic crust slowly sinks toward the mantle