Plate Tectonics and Continental Drift

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  • Created by: HGwizzard
  • Created on: 13-03-16 12:18
Oceanic Crust
Oceanic crust is new and denser than the continental crust. Generally 5km thick. Can sink and subduct and can be renewed and destroyed.
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Continental Crust
Continental crust is older and lighter than oceanic crust. Thickness is variable, 20-100km under large mountain ranges- Alps. Cannot sink or subduct and cannot be renewed or destroyed.
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Mantle
A dense hot layer of semi-solid rock approx 2,900km thick. The upper mate is semi-liquid made up of made of semi-liquid molten rock- magma. This moves due to convection currents which causes the tectonic plates to move.
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Core
Dense metallic composition
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Alfred Wegener
In 1915 proposed the theory of continental drift- which states that parts of the earths crust slowly drifts atop a molten mantle.
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Pangea
A super continent 225 million years ago. Broken up because of processes beneath the Earth's crust.
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Evidence in support of the theory of continental drift
1. Telephone cabes under the Altaic Ocean have been stretched and broken. 2. Similar fossils have been found in Africa and South America. 3. ,Volcanic islands have appeared in the middle of the ocean on plate boundaries.
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Conservative plate boundaries
When two plates try to slide slowly past each other. When they stick, pressure build up, it is released as a severe earthquake. As crust is neither created nor destroyed at conservative margins there are no eruptions.
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Collision plate boundary
When two plates moving towards each other are both continental crust. As continental crust cannot sink or be destroyed the land between them is buckled up and forms high fold mountains. Severe Earthquakes but no eruptions.
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Destructive plate boundary
When oceanic crust moves towards continental crust. the oceanic crust is heavier and is forced downwards pressure increases triggering violent earthquakes. The heat produced turns the descending crust into magma, this rises causing a violent eruption
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Constructive plate boundary
When two plates move apart. A gap appears causing a gentle eruption or lava flow. This creates new oceanic crust and forms a mid ocean ridge.
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Describe the distribution of earthquakes
Take place on most plate boundaries, on long narrow belts, the largest one goes around the entire Pacific Ocean. Also one that runs through the middle of the Atlantic Ocean. Another stretches across the continents of Europe and Asia.
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Describe the distribution of active volcanoes in relation to plate boundaries.
Mostly on plate boundaries. The largest belt goes around the Pacific Ocean 'Ring of Fire'. The second runs through the middle of the Atlantic Ocean.
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The Nazca Plate
A small oceanic plate off the coastline of South America. It has 5 triple junctions where plates come together. Produced largest recorded earthquake. Formation of the Andes.
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Other cards in this set

Card 2

Front

Continental crust is older and lighter than oceanic crust. Thickness is variable, 20-100km under large mountain ranges- Alps. Cannot sink or subduct and cannot be renewed or destroyed.

Back

Continental Crust

Card 3

Front

A dense hot layer of semi-solid rock approx 2,900km thick. The upper mate is semi-liquid made up of made of semi-liquid molten rock- magma. This moves due to convection currents which causes the tectonic plates to move.

Back

Preview of the back of card 3

Card 4

Front

Dense metallic composition

Back

Preview of the back of card 4

Card 5

Front

In 1915 proposed the theory of continental drift- which states that parts of the earths crust slowly drifts atop a molten mantle.

Back

Preview of the back of card 5
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