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32 Cards in this Set
- Front
- Back
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What is the evidence for continental drift?
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-Plate tectonics: coasts of Atlantic ocean could fit like a jigsaw puzzle if pushed together (Pangea) -familiar animals in seperate lands (fossil records) -magnetic strips known to exist on in the Atlantic -glacial striations *Wegener |
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explain the difference between divergence, convergence and transform movement
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Divergence: moving apart - causes trenches/rift valleys & upweling of magma in ocean - most in oceans Convergence: coming together - subduction (cont&oceanic) magma is formed in an upwelling & surfaces become hot - volcanoes/earthquakes Transform Movement: sliding past - San andreas fault |
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What is the significance of the magnetic stripes on the sea floor?
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Magnetic banding in the volcanic rocks on the Atlantic floor. Bands occurred in paired sets and trend from youngest (middle) to oldest (outside), suggesting that the ocean basis formed by spreading outward from the middle
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Orogenic belts
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systems of terrestrial mountains
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Continental shelves
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form the shoulders of the continents and in places such as Newfoundland coast or Europe, extend 200km or more seaward from shores (continental slope leads to ocean floor) |
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abyssal plain |
the deep ocean floor; the most extensive part of the ocean basin which lies btwn the mid oceanic ridges & trenches
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Mid Oceanic ridges
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found in the interiors of ocean basins, in the Atlantic basin - ridge runs NS through basin -In the Pacific, multiple ridges cross the basin -volcanic in origin -may form chain of islands |
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Trenches
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found on margins of basins running parallel to mountan chains -most lie among island arcs |
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Seafloor spreading
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plume spreads out in upper mantle - pills lithosphere apart - fractures develop - lithosphere seperates - rocks slip/jar = earthquake - new rock added
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Faults
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fractures along which rock has been displaced |
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What is the difference between plate tectonics and continental drift
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Plate tectonics caused continental drift Plate tectonics: explains inner workings of earth Continental drift: theory that all plates were connected |
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Trech
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result of subduction - as the oceanic plate subducts under neighbour, crust is drawn down to form a trench - depository for sediment
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Divergence
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lithospehre moving apart - causes trenches/rift valleys & upwelling of magma in ocean - most in oceans -Lithospheric plates move apart as new oceanic crust is created |
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Convergence
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Convergence: coming together - may be subduction/collision zones where mountains are formed (cont&oceanic) magma is formed in an upwelling & surfaces become hot - volcanoes/earthquakes - Nazca plate (oceanic&oceanic) pacific under bering, volcanic islands (cont&cont) mountains |
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Transform Movement
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Plates slipping laterally at right angles to a sea floor spreading in centre - no destruction (pacific + north american plates = san andreas fault) or zigzag Usually lots of earthquakes, but no volcanic eruptions |
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Transform Fault
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What is the connection between vertical/horizontal movement and plate tectonics?
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What are Euler poles & why do they occur in plate tectonics
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Fixed points that we must seperate/rotate around -plates rotate clockwise around euler poles |
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why do you get subduction on the west coast of canada?
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because the oceanic crust is more dense
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Why is convergence destructive?
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-because there is nowhere for the continents to go so it will create mountains |
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Magma vs. Lava
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Magma: molten rock stored IN crust Lava: magma that reaches the surface through volcano |
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Why does volcanism occur along mid oceanic ridge?
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because there is a divergent plate boundary which leads to seafloor spreading and an upwelling of magmaa |
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Does volcanism and seismicity always occur in the same place?
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No - volcanoes associated with earthquakes but not all earthquakes associated with volcanoes
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History of plate tectonics?
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why do you get transform faults along mid oceanic ridges??????
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two plates pull apart to form zig zag formations
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why do you get volcanoes independent of plate margins?
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because there are batholiths (hotspots) which cause hotspots that eventually erupt
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what is upwelling of magma?
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the upwelling of magma is when there are plates shifting and magma is forced up to the surface
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what are failed arms in triple point junctions?
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when spreding continues, one branch becomes inactive (failed arm) and turns into a long valley (collection zone) amazon, mississippi, africa |
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what is an orogeny?
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a period of mountain building
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History of the earth?
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1. accumulation of debris in solar system 2. magmatic differentation 3. basalitc/felsic crusts solidified 4. accumulation of continents 5. drifting of continents 6. eroison/deposition |
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How were the Himalays formed?
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collision between indian/eurasian plates
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