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37 Cards in this Set
- Front
- Back
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seismic waves |
reveal its concentric layers |
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seismographs |
record earthquake wave motion, primary, scondary, and surface waves |
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kinds of crusts |
continental and oceanic |
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continental crust |
made of andesitic rocks |
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oceanic crust |
basaltic composotion |
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wegener |
theory of continental drift |
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paleomagnetism |
magnetism frozen in rocks at the time of their formation, evidence of continental displacements and records |
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seismic waves |
messages from the interior |
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primary waves |
speediest, first to arrive at seismograph |
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secondary waves |
secondary to arrive, rock segments vibrate at right angles to travel direction |
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body waves |
p and s waves, penetrate deep in the interior |
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surface waves |
large motion waves that travel through the outer crust |
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discontinuities |
boundaries wehre seismic waves experience an abrupt change in velocity or direction |
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mantle |
upper mantle permit waves to travel faster |
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moho discontinuity |
30 km beneath surface of continents and less deep beneath ocean floors, between crust and mantle |
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Gutenberg discontinuity |
outer boundary of the core |
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shadow zone |
waves do not appear |
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isostasy |
condition of vertical balance, float at different heights in water |
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oceanic crust |
more dense |
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laurasia |
northern part of pangea |
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gondwana |
southern portion of pangea |
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pahthalassa |
universal ocean |
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spreading center |
plate moving away |
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trailning edge |
new oceanic crus is added to the trailing edge of each separating plate |
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guyots |
sea floor volcanoes with flat tops |
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transform plate boundary |
plates move sideways |
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subduction zone |
one slab plunges down when they collide |
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suture zone |
faulting, folding, metamorphism and intrusive activity |
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accretionary prism |
contorted and metamorphosed body of rock, continental oceanic convergence |
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melange |
complexly folded jumble of deformed and transported rocks, continental oceanic convergance |
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ophiolite suite |
distinctive assemblage of rocks composed of deep-sea sediment, continental oceanic convergence |
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blueschists |
metamorphic rock containing blue materials showing convergence of continental and oceanic plates |
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wilson cycle |
opening of new ocean basin along divergent zones and expansion on basin as seafloor spreading |
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inclination |
angel of the magnetic field with respect to he horizontal |
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inclination |
used to determine latitude |
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thermal plumes |
concentrated areas of heat |
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width of magnetic strips |
wide=long time, narrow=short |
