You feel the earth unsteady beneath your feet, shifting and shaking. It is an earthquake! That is what happens when rocks in the lithosphere have been stressed too much and break. The lithosphere is the rocky layer that covers the entire earth, both continents and oceans. It has two parts: the crust and the upper mantle.
The crust varies in thickness. Under the oceans it is only 3 to 5 miles deep, but the continental crust extends about 25 miles. At the surface the crust is air temperature, but at its deepest parts it can reach 1,600 degrees Fahrenheit. The most common elements in the rocky layer are oxygen, silicon and aluminum.
Below the crust, the top layer of the upper mantle is also part of the lithosphere. With the crust and mantle section combined, the lithosphere is about 50 feet deep. In addition to oxygen and silicon, the upper mantle also contains significant amounts of iron and magnesium. This part of the lithosphere is denser than the crust.
- Trinity College: Earthquakes: Material Properties
- Universe Today: What Is Lithosphere
- Georgia State University: Abundances of the Elements in the Earth's Crust
- Windows to the Universe: The Earth's Crust, Lithosphere and Asthenosphere
- Arizona State University: Crust and Mantle vs. Lithosphere and Asthenosphere
- Georgia State University: Structure of the Earth
About the Author
Living in upstate New York, Susan Sherwood is a researcher who has been writing within educational settings for more than 10 years. She has co-authored papers for Horizons Research, Inc. and the Capital Region Science Education Partnership. Sherwood has a Ph.D. in curriculum and instruction from the University at Albany.