15 terms

Plate Tectonics Quizlet

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Pangaea
the supercontinent that existed millions of years ago
fossil
any trace of an ancient organism that has been preserved in rock
mid-ocean ridge
in sea-floor spreading when molten material rises from the mantle and produces long chains of mountains
sea-floor spreading
the process by which molten material adds new crust to the ocean floor
deep-ocean trenches
deep underwater canyons that form when the ocean floor sinks below continental crust
plate-tectonics
the theory that states that pieces of Earth's lithosphere are in constant slow motion
convection currents
geologist think that the movement of Earth's plates are caused by these currents in the mantle
tectonic plates
a section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust
transform boundary
a plate boundary where two plates move past each other in opposite directions (for example the San Andreas fault in California)
divergent boundary
a plate boundary where two plates move away from each other (mid-ocean ridge or rift valley can form here)
convergent boundary
a plate boundary where two plates move toward each other (subduction or mountain building)
subduction
the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle
rift valley
created by two pieces of continental crust diverging or pulling away from each other
mountain
created by two pieces of continental crust converging or coming together
continental drift
Alfred Wegner's hypothesis that the continents were once joined together and have slowly moved apart