The Crust

• The crust is Earth’s outermost layer.

• It ranges in thickness from about 5 km to about 80km.

• The crust consists of solid rock which has cooled and hardened since Earth first formed.

• These rocks are composed mostly of silicates – minerals high in silicon and oxygen.

• The crust is made up of continental crust, which comprises Earth’s landmasses, and oceanic crust, which is covered by Earth’s oceans.

• Continental crust is thicker but less dense than oceanic crust.

• Continental crust has an average thickness of 30-50 km and an average density of about 2.7 g/cm³.

• It consists mostly of granite and other similar types of rock.

• Oceanic crust has an average thickness of 5-10 km and an average density of about 3.0 g/cm³.

• It consists mostly of basalt and other similar types of rock.

Earth’s outermost layer consists of continental crust and oceanic crust.

(Image: USGS, Wikimedia Commons)