Flashcards in The Restless Earth Deck (8)
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.
Crust, made of continental and oceanic crust. They meet at boundaries or plate margins.
Thicker and less dense.
Thinner and more dense.
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.
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.
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.