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chapter 7 vocab
Term | Definition |
---|---|
Pangaea | all the continents were once part of a supercontinent |
continental drift | continents are in constant motion on the surface of earth |
mid-ocean ridges | the mountain ranges in the middle of the oceans |
seafloor spreading | the process by which new oceanic crust forms along a mid-ocean ridge and older oceanic crust moves away form the ridge |
normal polarity | a state in which magnetized objects, such as compass needles, will orient themselves to point north |
magnetic reversal | occurs and the magnetic field reverses direction |
reversed polarity | a state in which magnetized objects would reverse direction and orient themselves to point north |
plate tectonics | earths surface is made of rigid slabs of rock, or plates, that move with respect to each other |
lithosphere | the cold and rigid outermost rock layer |
divergent plate boundary | forms where two plates separate |
transform plate boundary | forms where two plates slide past each other |
convergent plate boundaries | form where two plates collide |
subduction | the denser plate sinks below the more buoyant plate |
convection | the circulation of material caused by differences in temperature and density |
ridge push | ridge push moves lithosphere in opposite directions away from the mid ridge ocean |
slab pull | as a slab sinks, it pulls on the rest on the plate with a force |