Term
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Definition
The Earth's outermost layer of rock
oceanic crust: 5 km deep
continential crust: 35 km deep (50-70km under mountains)
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Term
| Mohorovicic discontinuity |
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Definition
| the boundary between the crust and the mantle; the feldspar disappears at this point and there is an overall change in rock mineralogy and density. |
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Term
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Definition
has a high percentage of iron and magnesium minerals.
ranges from base of crust to 2900km in depth. |
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Term
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Definition
extends from the base of the mantle and reachers to the center of the Earth (6370 km)
Earth's magnetic field is generated by the core, as a result of slightly different rotational velocities between the liquid and solid layers. |
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Term
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Definition
the rigid outer layer of the Earth, including the entire crust and the uppermost mantle.
Brittle fashion when subjected to force.
Thinner under oceanic crust and thicker under continental crust. |
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Term
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Definition
underlies the lithosphere
Sudden drop in seismic wave velocity
Rock behaves in a ductile manner
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Term
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Definition
Below the asthenosphere (225-250 km in depth)
pressures + high temperature= rocks behaving like solids until reaching the liquid outer core.
Zone of solid material. Includes lower mantle down to the boundary of the liquid outer core. |
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Term
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Definition
Plates move toward one another and contact.
Lithosphere is destroyed at these margins by subduction; occurs when one plate sinks below the other.
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Term
| Continent-Ocean convergent boundary |
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Definition
| Oceanic plate generally subducts beneath continental plate. |
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Term
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Definition
| When the oceanic plate is subducted, and as it descends into the asthenosphere, melting occurs. When the melting material rises back into the lithosphere, it may breach the surface and form these. |
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Term
| Ocean-Ocean Convergent Boundary |
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Definition
| the older, colder and denser plate subducts beneath the other. |
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Term
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Definition
| Volcanic island arcs are formed by ocean-ocean convergent plates when the rising melt material forms volcanoes under the surface of the ocean. |
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Term
| Continent-Continent Convergent Boundary |
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Definition
| two continental plates converge and form mountains due to no difference in density. |
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Term
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Definition
| plats move apart relative to one another, and create spreading centers |
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Term
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Definition
| the process of plates separating |
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Term
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Definition
| characterized by faulting and volcanism, this acts as the inital stage of plate separation and often occurs in continents. |
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Term
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Definition
| a rift valley that's covered in seawater |
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Term
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Definition
two plates slide past one another
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Term
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Definition
| the weight of the descending slab pulls the rest of the plate along with the subducting plate. |
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Term
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Definition
| as magma rises at oceanic ridges, its' heat causes the ridges to rise higher than the surrounding oceanic crust. As density increases, gravity pulls rock downhill, away from the ridge. |
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Term
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Definition
formalized in 1912 by Alfred Wegener.
Suggested that continents had once been united, forming a huge supercontinent termed Pangaea and then broke up into smaller continents, etc. |
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