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18 Cards in this Set
- Front
- Back
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what is continental rifting?
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rifting (breaking apart) of a continent
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what can continental rifting result in?
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the formation of a rift valley
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what is an example of continental rifting?
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east african rift valley
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what forms from continental rifting?
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a narrow ocean forms and seafloor spreading occurs
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what is an example of a narrow ocean forming from continental rifting?
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red sea
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what happens over time during continental rifting
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the ocean becomes progressively wider
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Describe the process of continental rifting
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heat builds up, the crust is like a blanket keeping it warm.
the heat weakens the crust and it breaks the magma keeps come up and pushing the plates apart creating oceanic materials |
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how is east african rift basin related to human evolution?
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it created a drastic shift to the climate from rainforest to grasslands ... so humans had to walk erect to conserve energy while gathering scarcer food
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what is variability selection hypothesis?
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it is the hypothesis that rapid changes in climate directly effect/correlate with drastic/rapid changes in human evolution
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what did environmental pressure/stress in the east african rift basin push human towards?
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bidpedalism, brainy, larger jaws
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What is pulsed Climate Variability hypothesis?
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concerning the east african rift basin where the continental rift has created drastic shifts in climate in alternating wet and arid periods. Huge lakes appeared and disappeared. shifts were rapid directly effecting human evolution
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what is the landscape of the east african rift basin over time
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EA went from a relatively flat area with abundant rainforests to a region of extreme topography. as the rift opened, a region of mountains, plateaus and deep rift valleys formed, creating the 'cradle of humanity'
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when was the east african rift basin formed?
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between 10 - 5 million years ago
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what happens to the moisture in the east african rift basin?
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the moisture comes up from the ocean into the mountains were it rises and condenses. then the dry air goes over the other side of the mountains
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how do we know about pulsed climate variability?
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sediments at the bottom of lakes tells us a story from pollen from plants and other organic materials. also the rift valley had volcanoes formed which created volcanic ash and magma which we can date
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what is radiometric dating?
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during one half-life half of the atoms of a radioactive isotope will change from parent to daughter atoms
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what is the link between tectonics and climate variability
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local climate responses to tectonic changes were likely amplified by the onset of walker circulation and modulated by precessionally forced variation is moisture availabilty in EA
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the concept of half life
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the amount of time necessary to reduce the number of parent atoms by 50% from the original number
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