Tectonics Revision

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The main structure of the Earth consists of 5 main parts and these are:

• Inner core- 1200 km thick

• Outer core- 2300 km thick

• Mantle- 2900 km thick

• Asthenosphere- Above mantle

• Crust- 30-100 km thick

The Earth is about 13,000 km in diameter with a solid metal ball which is the inner core.

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Destructive margin- plates move together

Construction margin- plates move apart

Convection current- plumes of heat that rise and fall in the mantle

Magma- hot molten rock

• How we found out about continental drift is the apparent fit of continents like puzzle pieces, fossil correlation, rock and mountain correlations and finally paleoclimate data.

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Constructive plates are where 2 continental plates move away from each other to cause volcanoes to be made as well as new crust.

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Destructive plates is when an oceanic plate which is denser is pulled down underneath a continental plate to form volcanoes and earthquakes.

~→↓■←

Collision plates is when 2 continental plates collide and both rise upwards towards the sky to create earthquakes and mountains.

■→↑ ↑←■

Conservation plate is when 2 continental plates rub past each other as they go in opposite directions and these cause earthquakes.

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Earthquakes happen because tectonic plates moving in opposite directions sometimes get stuck which means the tension builds up. One plate will eventually jerks past the other plates and the tension is released causing the earthquake and seismic waves travel outwards and the crust shaking is known as the actual earthquake.

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■ Tectonics and the Earth