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PLATE TECTONICS
Drifting Continents, Sea-Floor Spreading, The Theory of Plate Tectonics
Term | Definition |
---|---|
Alfred Wegener | a 1910 German scientist |
continental drift | the hypothesis that the continents slowly move across Earth's surface |
Pangaea | the name of the single landmass that began to break apart 200 million years ago and gave rise to today's continents |
fossil | the preserved remains or traces of an organism that lived in the past |
mid-ocean ridge | an undersea mountain chain where new ocean floor is produced; a divergent plate boundary |
sea-floor spreading | the process by which molten material adds new ocean crust to the ocean floor |
deep-ocean trench | a deep valley along the ocean floor beneath which oceanic crust sinks slowly toward the mantle |
subduction | the process by which oceanic crust sinks beneath a deep-ocean trench and back down into the mantle at a convergent boundary |
plate | a section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust |
divergent boundary | a plate boundary where two plates move away from each other |
convergent boundary | a plate boundary where two plates move toward each other |
transform boundary | a plate boundary where two plates move past each other in opposite directions |
plate tectonics | the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle |
fault | a break in Earth's crust along which rocks move |
rift valley | a deep valley that forms when two plates move apart |