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31 Cards in this Set
- Front
- Back
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Who proposed the idea of continental drift? |
Alfred Wegener |
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When was the idea of continental drift proposed? |
1912 |
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What was the idea of continental drift? |
-continents were connected in one land mass called Pangaea that broke apart 200 million years ago -they drifted into the positions they're in now |
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Why was the idea of continental drift not accepted by the scientific community? |
Wegener couldn't explain how the continents moved |
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What are the five pieces of evidence to support continental drift? |
-puzzle like fit of the continents -animal fossils (mesosaurus) -plant fossils (glossopteris) -climate (glacial deposits found in warm continents) -rocks (similar structures in continents that were once connected) |
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Who proposed the idea of seafloor spreading? |
Harry Hess |
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What is seafloor spreading? |
-seafloor separates and magma comes up through crack
-new seafloor moves away from the ridge, cools, and sinks |
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What are the two pieces of evidence that support seafloor spreading? |
-older rocks are farther away from the ridges -rocks track the magnetic field changes |
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When was the idea of plate tectonics proposed? |
1960's |
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What does the idea of plate tectonics explain? |
explains the features and movement of Earth's surface |
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What theory is formed by putting together seafloor spreading and continental drift? |
plate tectonics |
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What are plates made from? |
parts of the crust and upper mantle |
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What layer do plates move on? |
asthenosphere |
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What are the three types of plate boundaries? |
divergent convergent transform |
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What causes the plates to move? Describe how it works. |
convection
Hot fluid rises to the surface, cools, sinks, heats, rises, etc. |
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Describe a divergent boundary |
plates moving apart |
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What forms at a divergent boundary? |
mid-ocean ridges and rift valleys
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Describe a convergent boundary |
-plates moving together -denser plate goes below the other one |
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What can form at a convergent boundary? |
mountains and volcanoes |
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Describe a transform boundary |
-plates slide past each other - different speeds, same direction -different directions |
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What happens at transform boundaries? |
earthquakes |
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How do scientists test the rate of movement of plates? |
satellites and lasers |
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Molten Rock flows onto the seafloor and hardens as it cools ____ Hot, molten rock is forced upward toward the seafloor at a mid-ocean ridge ____ New seafloor moves away from the ridge, cools, becomes denser, and sinks ____ Molten rock pushes sideways in both directions as it rises, moving the mantle with it ____ |
C A D B |
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large, ancient landmass that was composed of all the continents joined together |
Pangaea |
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theory that Earth's crust and upper mantle are broken into plates that float and move around on a plasticlike layer of the mantle
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plate tectonics |
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plasticlike layer of Earth on which the lithospheric plates float and move around
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asthenosphere |
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Wegener's hypothesis that all continents were once connected in a single large landmass that broke apart about 200 million years ago and drifted slowly to their current positions
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continental drift |
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Harry Hess' theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge |
seafloor spreading |
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current in Earth's mantle that transfers heat in Earth's intereior and is the driving force for plate tectonics |
convection current |
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rigid layer of Earth about 100 km thick, made of the crust and part of the upper mantle |
lithosphere |
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a large section of Earth's oceanic or continental crust and rigid, upper mantle that moves around on the asthenosphere |
plate |
