Volcanoes 0.0 / 5 ? GeographyRestless EarthGCSEAQA Created by: AliceHornerCreated on: 20-09-16 21:16 Destructive plate margins An oceanic plate and a continental plate move towards each other The denser oceanic plate subducts under the continental plate The oceanic plate is melted in the magma under the crust and a pool of magma forms The magma erupts through 'vents' in the surface to form a volcano 1 of 4 Constructive plate margin Two plates move away from each other Magma rises up into the gap that is formed between the two plates, forming new crust or a volcano 2 of 4 Composite volcanoes Found at destructive margins Eruptions may be a pyroclastic flow - hot steam, ash, rock and dust Eruptions infrequent but often violent Steep-sided Made of layers of ash and lava, that have erupted, cooled and hardened The lava is thick, flows slowly and hardens quickly 3 of 4 Shield volcanoes Found at constructive margins Eruptions are frequent but gentle Low and flat Made up of only layers of lava The lava is runny and spreads over a wide area 4 of 4
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