Crust

Definition

The crust is the outermost solid layer of a planet. It is composed primarily of silicate rocks and varies in thickness.

5 Must Know Facts For Your Next Test

1. The Earth's crust is divided into two types: continental crust and oceanic crust.
2. Continental crust is thicker, ranging from 30 to 50 km, while oceanic crust is thinner, averaging about 7 km.
3. The crust makes up less than 1% of Earth's total volume.
4. Tectonic plates are sections of the Earth's crust that move over the mantle, causing geological activity like earthquakes and volcanic eruptions.
5. The boundary between the Earth's crust and mantle is called the Mohorovičić discontinuity or Moho.

Review Questions

Related terms

Mantle:

The layer beneath the Earth's crust composed mainly of silicate minerals rich in magnesium and iron.

Tectonic Plates: Large sections of Earth's lithosphere that move over the asthenosphere, leading to seismic activity.

Lithosphere:

The rigid outer part of Earth, consisting of the crust and uppermost mantle.