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Continental Crust 

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Continent continent collision USGS

Continental crust underlies the worlds major landmasses and is composed of high silica granitic composition rocks such as granite or its metamorphic equivalent gneiss. Continental crust sits on its tectonic plate ,surrouded by oceanic crust which move around the globe due to plate tectonics. They can be compared to rafts floating on the mantle.

Continental crust has evolved over the history of the earth through the fractional crystallisation (separation) of Si rich minerals in the process of magma generation in subduction zones.

A tectonic plate can consist of both continental and oceanic crust. Continetal crust is from 25km thickening 70km under mountain ranges. 40% of the earths surface is continental crust. Continental crust takes up 70% of the volumeof the earths crust.

When two pieces of continental crust collide due to plate movements mountain ranges are formed such as The Himalayas.

Himalayan Collision Zone USGS