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37 Cards in this Set
- Front
- Back
Pangaea |
The name of the single landmass that began to break apart 200 million years ago |
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Fossil |
The preserved remains or traces of an organism that lived in the past |
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Mid-ocean ridges |
An undersea mountain chain where new ocean floor is produced; a divergent plate boundary |
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Sea-floor spreading |
The process by which molten material adds new oceanic crust to the ocean floor |
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Deep-ocean trenches |
A deep valley along the ocean floor beneath which oceanic crust slowly sinks towards the mantle |
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Subduction |
The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary |
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Plates |
A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust |
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Divergent boundary |
A plate boundary where 2 plates move away from each other |
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Convergent boundary |
A plate boundary where 2 plates move toward each other |
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Transform boundary |
A plate boundary where 2 plates move past each other in opposite directions |
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Faults |
A break in Earth's crust along which rocks move |
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Rift valley |
A deep valley that forms where 2 plates move apart |
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Stress |
A force that acts on rock to change its shape or volume |
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Normal fault |
A type of fault where the hanging wall slides downward; caused by tension in the crust |
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Tension |
Stress that stretches rock so that it becomes thinner in the middle |
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Reverse fault |
A type of fault where the hanging wall slides upward; caused by compression in the crust |
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Compression |
Stress that squeezes rock until it folds or breaks. |
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Strike-slip fault |
A type of fault in which rocks on either side move past each other sideways with little up or down motion |
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Shearing |
Stress that pushes masses of rock in opposite directions, in a sideways movement |
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Plateau |
A large landform that has high elevation and a more or less level surface |
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What was Wegener's hypothesis about the continents? |
Wegener's hypothesis was that all the were once joined in a single landmass and have since drifted apart. |
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Evidence from land features |
Mt. ranges on South America line up, and coal fields in Europe and North America match up |
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Evidence from fossils |
Some of the same Fossils became separated once Pangaea split apart |
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Evidence from climate |
Tropical fossils have been found near the poles; this means that this place was near the equator, but drifted toward the poles |
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Why was Wegener's hypothesis rejected? |
He couldn't identify the cause of continental drift, but we have found that it's from convection currents. |
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What did scientists use to map mid o. r.? |
Sonar- uses sound waves to measure the distance to an object |
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What is sea f. S.? |
S.f.s. adds more crust to the ocean floor. At the same time, older strips of rock move outward from either side of the ridge. |
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Evidence from ocean material |
Pillow lava- when molten material hardens quickly after erupting underwater |
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Evidence from magnetic stripes |
Rock lines up in the direction of Earth's magnetic poles, poles occasionally reverse themselves |
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Evidence from drilling samples |
Rock farther from a ridge: older, vice versa |
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The process of subduction |
As oceanic cools, it gets more dense; when it collides with continental crust, it sinks into the mantle, because it is more dense; sinks into a deep ocean trench |
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Subduction and Earth's Oceans |
Subduction and sea floor spreading can change the size and shape of the oceans; ocean renewed about every 200 mil. yrs. Oceans get bigger when crust forms faster than it can sink into the mantle, vice versa |
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Plate motions over time |
Scientists use satellites to measure plate movement, move 1-12 cm. per year |
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How does stress change Earth's crust? |
Tension, compression, and shearing |
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How do faults form? |
When enough stress builds up in rock, the rock breaks, creating a fault |
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Folding Earth's crust |
Rocks stressed by compression can bend without breaking and can form anticlines and synclines |
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Stretching Earth's crust |
Fault block mts.- when hanging walls slip down, the footwall stays up and forms into a mt. |