Earth's crust

The Earth's crust is the Earth's hard outer layer. It is less than 1% of Earth's volume. The crust is made up of different types of rocks: igneous, metamorphic, and sedimentary rocks.

Below the crust is the mantle. The crust and the upper mantle make up the lithosphere. The lithosphere is made of tectonic plates, which move very slowly.

The crust is of two different types. One is the continental crust (under the land) and the other is the oceanic crust (under the ocean).

1. The continental crust is thicker, 30 km (20 mi) to 50 km (30 mi) thick. It is mostly made of less dense, more felsic rocks, such as granite.
2. The oceanic crust is thinner, 5 km (3 mi) to 10 km (6 mi) thick. It is made of denser, more mafic rocks, such as basalt.

The temperature of the crust increases with depth because of geothermal energy. Where the crust meets the mantle the temperatures can be between 200 °C (392 °F) to 400 °C (752 °F).^[1] The crust is the coldest layer because it is exposed to the atmosphere.

1. ↑ http://www.channel4.com/science/microsites/S/science/nature/journey.html Earth