16 terms
Plate Tectonics Quizlet
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
an undersea mountain chain where new ocean floor is produced at a divergent boundary
sea-floor spreading
the process by which molten material adds new crust to the ocean floor
deep-ocean trenches
deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle at a convergent boundary
plate-tectonics
the theory that states that pieces of Earth's lithosphere are in constant slow motion
convection currents
currents in the mantle that cause the movement of Earth's plates
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
a deep valley that forms on land at a divergent boundary where two plates move apart
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 in a single landmass and have slowly moved apart
subduction zone
the area where oceanic crust sinks beneath continental crust