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36 Cards in this Set
- Front
- Back
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Alfred Wegner proposed that this super continent was assembled about 250 million years ago.
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Pangaea
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What evidence was used to support Wegner's continental drift hypothesis?
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1. Fit of the continents
2. Mathcing fossils across oceans 3. Matching rock types and mountain ranges 4. Climate data |
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What are the types of lithosphere?
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1. Oceanic lithosphere
2. Continental lithosphere |
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Overall "basaltic" which lithosphere is denser and thinner?
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Oceanic lithosphere
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Overall "granitic" which lithosphere is less dense and thicker?
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Continental lithosphere
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What are the three types of Plate Boundaries?
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1. Divergent
2. Convergent 3. Transform |
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What plate boundaries move apart & new oceanic crust is formed?
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Divergent
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What are the characteristics of Oceanic Ridges?
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underwater mountain chains, basalt cools to produce new oceanic lithosphere & Shallow focus earthquakes occur here.
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In divergent plate boundaries as plates move apart what develops?
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Rift Valleys
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What rises as continents break apart?
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molten rock rises from asthenosphere
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What are the Stages of Formation of Ocean Basins?
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A. Initial Stage - East African Rift Valley
B. Later Stage - Red Sea or Gulf California (Sea Forms between Continents ) C. Late Stage - Ocean Basin Formed - Atlantic Ocean |
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What type of plate boundaries is it when two plates collide?
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Convergent
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What is Oceanic- Continental plate boundary?
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When oceanic lithosphere subducts beneath continental plate
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What is a trench?
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Physical depression on the sea floor.
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What forms at the roots of mountains in a Oceanic- Continental Boundary?
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Igneous intrusions
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What is generated as plates subduct in Oceanic- Continental Boundary?
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Earthquakes
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Examples of Oceanic- Continental Boundary?
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Andes Mountains (South America)
Cascades (North America) |
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What forms the continental volcanic arc that parallels trench?
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Andesitic lava eruptions
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Older denser plate subducts in what plate boundary?
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Oceanic - Oceanic
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What is an Example of Oceanic Oceanic?
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Aleutian Islands & Tongs Islands
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What is Continental- Continental plate boundary?
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When two continents converge, neither will subduct (both are too buoyant).
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Characteristics of folded mountain belts
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-Rocks have been faulted and folded.
-Igneous intrusions (plutons). -Metamorphic Rocks. -Pieces of oceanic crust. |
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Examples of Continental Continental plate boundary.
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Himalayas (Asia) and Appalachian Mountains.
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What are Transform Boundaries?
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Where two plates move past each other.
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What are the characteristics of Transform Boundaries?
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1. Make relative motion of the plates possible.
2. Most transform faults connect segments of oceanic ridges. 3. Some transform faults cut through continental crust. |
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Examples of transform faults that cut through continental crust.
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San Andreas Fault connects the spreading ridge in the Gulf of California and the Cascadia subduction zone (Oregon and Washington)
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What is the evidence for plate tectonics?
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1. Paleomagnetism
2.Ocean drilling 3. Hot spots 4. Earthquake patterns |
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What is Paleomagnetism?
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Study of ancient magnetism & rocks.
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What evidence did Polar wandering have?
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Continents have moved in relation to a "fixed" pole
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What is Magnetic reversals?
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The earth's magnetic field switches polarity; the South pole becomes dominant pole during a time of reverse polarity
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What evidence was offered with Ocean Drilling?
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Indicates that there is no oceanic crust older than 180 million years.
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With Ocean Drilling what was discovered about the ocean crust?
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Ocean crust increases in age with increasing distance from an oceanic ridge.
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What is Benioff Zones?
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Inclined zones of earthquakes trenches
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What evidence was offered with Earthquake patterns?
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Close association between earthquakes and plate boundaries
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What evidence was offered with Hot Spots?
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Volcanoes in the Hawaiian Island-Emperor Seamount chain increase in age in NW direction.
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Where are the only active volcanoes?
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In Hawaii which is located directly over a hot spot
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