ENVS2003 Lecture Notes - Lecture 9: Oceanic Crust, Subduction, Surface Mining
29 Jun 2016
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Document Summary
Forces inside the earth cause continents to drift, split and crash into each other. A layered sphere -core: interior of the earth, composed of hot metal, solid center, semi fluid outer, 2,900-5,000 km in diameter. Crust: cool, lightweight brittle rock that floats on the mantle. Plates: large pieces of land broken and moved by huge convection currents on the upper layer of the mantle. Magma: molten rock that gets pushed up from the mantle through cracks in the oceanic crust and piles underwater to create ocean ridges. Earthquakes are caused by grinding and jerking as plates slide past each other. When an oceanic plate collides with a continental landmass, the ocean plate will be subducted and move into the magma where it is melted and the continent will be pushed up. More earthquakes and volcanoes occur here than any other place on the planet.
