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Flashcards in The Restless Earth Deck (8)
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How does a fold mountain form?

In a huge gap between plates, sedimentary rocks thousands of metres thick formed from compacted sediment in the huge depression called the geosyncline. These were forced upwards in folds when the two plates moved towards each other. There were upfolds (anticlines), downfolds (synclines) and overfolds.


Tectonic plates?

Crust, made of continental and oceanic crust. They meet at boundaries or plate margins.


Continental plate?

Thicker and less dense.


Oceanic plate?

Thinner and more dense.


Destructive margins?

When two plates are moving towards each other. The oceanic plate is forced under into the mantle and destroyed. This creates volcanos and ocean trenches. When two continental plates meet they smash together but destroy no crust.


Constructive margins?

When two plates are moving away from each other. E.g mid Atlantic ridge. Magma rises from the mantle to fill the gap and cools, creating new crust.


Conservative margins?

When two plates are moving sideways past each other, or moving in the same direction but at different speeds. Crust isn't created or destroyed.



At destructive plate margins the oceanic plate goes under the continental plate because it's more dense forming ocean trenches. The oceanic plate melts and is destroyed forming a pool of magma. The magma rises through the cracks called vents forming a volcano.