The continental crust is made up of sedimentary, igneous and metamorphic rock. Sedimentary rocks are rocks that have been formed by atmospheric pressure, living organisms and gravity. They are created when sediments consolidate over eons.
Igneous rocks are formed by the cooling of magma, found deep in the Earth, or lava flows. Intrusive igneous rocks include granite and tonalite. These rocks work their way to the surface over millions of years. Other rocks result when lava cools on the surface of the Earth. These include rocks such as obsidian and basalt.
Metamorphic rock is rock that has transformed, also over a very long time, into another type of rock. These rocks include marble, which is made from the transformation of limestone and gneiss, which forms from schists and muscovite.
The rocks in the continental crust are some of the oldest rocks on Earth; some of them are nearly as old as the planet itself. The continental crust is also made up of 15 tectonic plates that float on the viscous rock at the very top of the Earth's mantle. The movement of these tectonic plates cause continents to come together and split apart over the life of the planet. They create mountain ranges and are responsible for phenomena such as earthquakes and volcanic eruptions.