Lithosphere vs Crust
The difference between lithosphere and crust finds its base in the formation of the earth. Earth, which is a spheroid, is not a monolithic, uniform structure, but divided into layers having different characteristics. Starting from the center of the earth, it is the core that is encountered first (3400km radius). Then comes the mantle that surrounds this core and has a radius of 2890km. The surface of the earth down to the mantle that literally floats on the mantle is called the crust and is made of basalt and granite. The lithosphere is a layer that includes the crust and the uppermost portion of the asthenosphere. Thus, the lithosphere contains the oceanic crust, continental crust, as well as the uppermost mantle. It confuses many as to why there are two names for the same layer of earth. Well, it has to do with different ways scientists study the earth and its properties. While lithosphereis studied with the mechanical properties of the earth in mind, the crust is studied with a focus on the chemical composition of the earth. There are some more differences that will be explained in this article.
What is the Crust?
Of the many layers of the earth, the crust is the outermost layer and is the skin of the earth. The oceanic floor is a crust. The continental crust, as well as the mountains, is also included in the crust. While the thickness of the crust below the oceans is just 5-10km, it is as much as 60km under some mountain ranges.The crust is not as thick as either the mantle or the core of the earth. However, this is a very important part of the earth’s layers as all that is favorable to life is on this layer of the earth.
What is the Lithosphere?
The word lithosphere comes from lithos, meaning rocks, and sphere. Thus, it is the study of rocks that form the surface of the earth and includes the crust, which is the skin of the earth and the uppermost mantle. This layer goes below the surface of the earth to about 70-100km. It is rigid and a relatively cool section of the earth that is believed to be floating on top of much warmer and molten material that makes the lower mantle.
The region below thelithosphere is made up of asthenosphere (asthenes means weak). These are rocks that are at a high temperature, and are thus, less rigid and at places even flowing because of high pressure. Thus, the crust and the upper mantle that compose lithosphere float on top of the asthenosphere. This asthenosphere remains in a state of continual motion. It is this motion that causes plates of lithosphere to rub against each other. This process is called plate tectonics, and is responsible for many natural disasters such as volcanoes, earthquakes, landslides, and continental drift.
In the lithosphere, there are boundaries that are known by the name subduction zones. The volcanic activity that we get to see happens in these subduction zones. These boundaries between the tectonic plates have a deep effect on the surface shape of the earth.
What is the difference between Lithosphere and Crust?
Crust and lithosphere are both the names of the outermost surface of the earth. However, there are many vital differences between the two.
• Formation:
• The crust is the topmost layer out of the three layers called the core, mantle, and crust that make up the earth.
• The next layer down the crust is the uppermost part of the mantle, and the two together make up the lithosphere.
• Nature:
• Crust consists of the things that are necessary for life.
• Lithosphere is broken into giant plates that fit in like a jigsaw puzzle. There is continuous movement of these tectonic plates on less dense, almost fluid mantle that makes up asthenosphere.
• Effect:
• Crust is the part on earth that supports life.
• Because of the movement of rocks in lithosphere natural disasters like earthquakes, volcanoes, and landslides happen.
• Focus of Study:
• Crust is studied having the chemical composition of the earth in mind.
• Lithosphere is studied having the mechanical properties of the earth in mind.
• Parts:
• Crust can be divided as oceanic crust and continental crust.
• Lithosphere also can be divided as oceanic lithosphere and continental lithosphere.
Images Courtesy: The crust and lithosphere via Wikicommons (Public Domain)
