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21 Cards in this Set
- Front
- Back
what are fold mountains? |
1000's km long belts. range in height up to 8.8km form at destructive boundaries due to compression. composed of strongly folded and faulted metamorphic rocks. shallow-focus earthquakes are common |
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what is a rift valley/graben? |
a linear strip of crust that has slipped down along two inward dipping normal faults. |
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what is a craton? |
an area of flat,cores of ancient continents. composed of highly deformed rocks called gneiss they are aseismic |
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what is the continental shelf? |
formed of continental crust, and is covered in beds of clastic sediments (sand, and clay). |
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what depth from 0 do the continental shelfs range too? |
200m. |
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what is the continental slope? |
the steeper (4 degree) part of the continental crust extending ffrom the continental shelf. |
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what depth range is the continental slope? |
at 200m and all the way down to the abyssal plane, and the depth from these two points can be 1500m-3500m. |
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what are turbidity currents? |
submarine avalanches which transport sediment down the continental slope. |
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what does the end of the continental slope mark? |
the start of the oceanic crust |
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what is an abyssal plane? |
a 3-5km deep ocean basin. |
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state 3 characteristics of the abyssal plane |
flat and underlain by oceanic crust covered by thin beds of fine grained pelagic sediments asesimic |
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how deep, wide and long are submarine valleys? |
11km deep 150km widde 1000s km long |
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what is a seamount? |
a submarine basalt volcano, rising up to 1000m off the sea floor without reaching the sea level.
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what is a guyot? |
a seamount with a flat, eroded top |
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state 4 characteristics of a Mid Ocean Ridge |
rises 2-3km above the abyssal plane and are around 1000km wide the centre contains a deep rift valley submarine eruptions of basalt occur occur at constructive boundaries and shallow focus earthquakes are common |
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in what year did alfred Wegener propose his hypothesis of continental drift? |
1915 |
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a super continent was formed when? and name this continent |
250 million years ago and its called pangea |
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what were the 2 split up continents called once pangea splt? |
Laurasia and gondwanaland |
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state 3 reason why continents dont fit together perfectly |
erosion sea level change depostion of materials |
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what is the name of the fossil which has been found on all southern continents? |
glossopteris ` |
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why can rocks provide evidence for continental drift? |
because rocks form in different climates, for example sandstone has to be formed in a hot climate where there is sand, so rocks show that the continents have moved because the rocks are no longer in climates that they can form. |