types of plate margins

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Types of plate Margin

Earthquakes and volcanoes occur at constructive margins

·         Constructive margin = two plates are moving apart (diverging).

·         Mantle under pressure from plates above. When moves apart, pressure released at margin.

·         Release of pressure causes mantle to melt, producing magma.

·         Magma less dense than plate above, so rises and can erupt to form a volcano.

·         Plates don’t move in uniform way (some parts move faster than others – pressure builds up), when pressure becomes too much the plates cracks, creates fault line causing an earthquake. (Further earthquakes occur along fault line once it has been created).

·         Constructive margins create two different landforms:

Mid-Ocean Ridge

Ø  Where diverging plates are underwater mid-ocean ridge forms

Ø  E.g. Mid-Atlantic Ridge where Eurasian plate and North American plate are moving apart

Ø  Underwater volcanoes erupt along mid-ocean ridges and can build up above sea level

Ø  E.g. Iceland formed by build-up of underwater volcanoes along Mid-Atlantic Ridge

Rift Valley

Ø  Plates diverge beneath land, rising magma causes continental crust to bulge and fracture, forming fault lines

Ø  As plates…

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