16 terms

Topic 5B Plate Tectonics

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Convergent Boundary
a plate boundary where two plates move into each other.
Divergent Boundary
a plate boundary where two plates move apart from each other
Plate Tectonics
this theory states that the crust is broken into 12-20 slabs of solid rock that are in constant motion
Continental Drift
this theory states that all the continents were once connected as one super continent called Pangaea.
Subduction
this occurs at convergent plate boundaries when one plates is forced beneath the other plate
Transform boundary
a plate boundary where two plates move parallel to each other
Paleomagnetism
the study of the Earth's present and past magnetic field
Normal Polarity
when magnetic North is where geographic North is
Reversed Polarity
when magnetic North is where geographic South is
Plate
a large section of the lithosphere
Hot spot
an area of the Mantle where large amounts of molten material rise to the lithosphere
Seafloor spreading
a divergent plate boundary found on the ocean floor
Trench
the deepest areas in the ocean that form when an oceanic plate subducts beneath a continental plate
Oceanic ridge
the under water mountain range that forms at a divergent plate boundary beneath the ocean
Magma plume
as a subducting plate melts, some magma will rise to the surface in a balloon shape structure
Convective flow
the movement of material in the upper Mantle called the Asthenosphere which is caused by differences in density of molten rock