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60 Cards in this Set
- Front
- Back
plate tectonics
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a theory that explains the motions of earth's continents that is driven by sea floor spreading
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lithosphere
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earth's crust
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continental drift
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a theory that says that all of the continents are moving across earths surface (part of plate tectonics)
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evidence of continental drift
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fossil evidence, glacial striations/grooves, rock deposits, jigsaw puzzle fit of modern currents
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pangeaa
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super continent
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Wegener
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proposed the theory of continental drift
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Harry Hess
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convection in the mantle is the driving force behind magma rising to the surface causing sea floor spreading
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hot spots
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long lived source of magma within the asthenosphere and below the moving lithospheric plates. Ex. Hawaii
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active continental margin
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if the coastline of a continent lies along a plate boundary
ex. frequent earthquakes, numerous volcanoes and mountains, oceanic trenches occur (West coasts of US and Africa) |
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passive continental margin
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occur when no plate boundary is near the coastline. Ex - stable areas with alot of shallow water off coasts (East coasts of US and Africa)
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mountains ranges form this way
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when oceanic crust collides with continental crust, the crust wrinkles up forming mt ranges (Rocky Mts, Andes)
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mountain ranges form this way
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continents collide (Swiss Alps, Himalayas)
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faults
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a crack in the earth's crust along which movement occurs
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normal faults
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when one side of a fault drops lower than the other side
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reverse faults
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when one sideof a fault rises higher than the other side (imp in mountain building)
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strike slip faults
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when 2 sides of a fault move horizontally past one another
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folds
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during plate collisions, rock layers that were once horizontal are crumpled into folds
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anticline
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if the fold points upward
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syncline
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if the fold points down
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volcanoes
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friction between colliding plates can generate magman which rises through the crust to form volcanoes
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uplifting
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level layers of rock are raised to a higher elevation in a mountain building event
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tilting
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when level rock layers get pushed upwards, they can be tilted as the form anticlines or synclines
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overturning
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severe tilting causes rock layers to lie bottom side up
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evidence of overturning
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ripple marks in rocks from waves in shallow water, cross bedding from shifting water, mud cracks when wet mud dries up, if shell fossils have their open sides down - no overturning has occurred.
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joints
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cracks or breaks in the bedrock where no apparent movement has occurred
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Dome Mountains
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a huge fold of rock layers that forms a small mountain (Adirondacks are dome mts)
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lithosphere (crust)
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100km thick
much thicker under the continents than it is under the ocean basins |
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lithosphere
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floats on the upper layer of the mantle called the asthenosphere
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lithosphere
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as heated magma rises from the Earth's core, convection currents move the plates of the lithosphere around
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sea floor spreading
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at the center of the Atlantic Ocean the plates are separating
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separation clues
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1-similar mineral compositions and ages of rocks
2-similar mineral alignment of magnetic particles toward normal and reverse polarity) |
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converging (convergent plate boundaries)
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Subduction zones - where old, cool lithosphere sinkds into earth
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diverging (divergent plate boundaries)
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Rift Boundaries - lithospheric plates are moving away from one another
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transform (strike -slip)
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lithospheric plates are sliding against one another
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boundary movement (caused by upper mantle convection currents)
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at diverging boundaries - plates undergo "ridge push"
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boundary movement (caused by upper mantle convection currents)
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at converging boundaries, the plates undergo "slab-pull"
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earths 4 layers
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crust, mantle, outer core, inner core,
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divergent boundaries
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- rift valleys and ridgesm fault block mountains, new crust is formed here
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convergent boundaries
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subduction zones - ocean trenches, folded mountain ranges, volcanic arc mountain ranges,island arcs, fold block mountain ranges
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transform boundaries
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fault block mountains
-many strong earthquakes -no crust is created or destroyed ex - San Andreas fault |
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oceanic - continental
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the denser oceanic crust (basaltic) gets subducted
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oceanic-oceanic
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the older, denser of the two oceanic gets subducted
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continental-continental
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the denser, older of the two may be partially subducted
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fault-block mountains
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the Himalayas and the Appalachian mts
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Alfred Wegener proposed the theory of Continental drift
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True
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the theory of CD was accepted as soon as it was proposed
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false
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the theory of Plate tectonics states that earth's outermost layer, the lithosphere is broken into 10 rigid pieces called plates
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false
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the plates all move in the same direction and at the same speed
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false
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the place where the plates meet is called a plate boundary
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true
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boundaries have different names depending on how the 2 plates are moving in relationship to each other
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true
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boundaries in which the plates are crashing together are called transform boundaries
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true
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earth is divided into 4 chemical layers - core, mantle,the crust and the shell
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false
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the core is divided into solid inner core and a liquid outer core
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true
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the mantle is made of minerals rich in the elements iron, magnesium, silicon and oxygen
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true
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two types of crust are
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oceanic crust and contintental crust
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oceanic crust is made mostly of relatively dense rock called
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basalt
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the outermost layers of the earth can be divided by their physical properties into the
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lithosphere and mantle
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The rigid outermost layer made of crust and uppermost mantle
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lithosphere
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the asthenosphere is part of the mantle that flows, a characteristic called
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plastic behavior
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