Crust

This site tells the story of the history of the universe. Click Earlier and Later to follow the story.
Note: Many facts have been simplified to make them easier to understand.
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The crust of the Earth is a thin rigid layer of rock. It floats on the mantle.

It is made mostly of a layer of dark rock called basalt 5-10 km thick. The oceans lie above this layer. Trapped in this basalt are lumps of thicker rock similar to granite 30 - 40 km thick. These lumps stick out of the oceans to form the continents.