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22 terms

Vocabulary 9

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Pangaea
The name Wegner gave to the supercontinent.
Transform Fault Boundary
Occur when two plates grind past each other.
Convective flow
Warm, less dense material rises and cooler, more dense material sink.
Rift Valley
Deep faulted structures that occur at a divergent boundary between two landmasses.
Paleomagnetism
Rocks that show the location of the magnetic poles at the time of their formation
Ridge Push
Oceanic lithosphere slides down the sides of the oceanic ridge, pushing the plates apart.
Plate
The segments of the lithosphere.
Trench
The surface feature created at a subduction zone.
Reverse Polarity
When rocks show opposite magnetism as the present magnetic field.
Normal Polarity
When rocks show the same magnetism as the present magnetic field
Plate Tectonics
The theory that the rigid lithosphere of Earth is divided into different sections that "float" along on top of the weaker mantle region.
Convergent boundary
Occur when two plates move toward each other.
Oceanic ridge
The elevated seafloor that develops along a divergent plate boundary.
Hot spot
A rising plume of mantle material is located below the crust, which melts the rock near the surface, allowing magma to move though.
Continental drift
The continents were once connected as a single supercontinent, and slowly moved apart.
Continental volcanic arc
Produced in part by the volcanic activity that is caused by the subduction of oceanic lithosphere under a continental plate.
Slab-pull
Old oceanic crust, which is relatively cool, sinks into the asthenosphere (mantle) and "pulls" the trailing lithosphere (crust) along
Seafloor spreading
The process by which plate tectonics produces new oceanic lithosphere
Mantle Plume
Hot plumes of rock that are the upward flowing arms in mantle convection
Subduction zone
Destructive plate margin where oceanic crust is being pushed down into the mantle by a second plate.
Volcanic island arc
A chain of small volcanic islands created by the subduction of oceanic plates under another oceanic plate.
Divergent boundary
Occur when two plates move apart