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Lithosphere

The word “geo” means Earth. This means when we study geology,” we study our Earth. Geologists study the lithosphere.
The lithosphere covers much of the inner layers.

Earth’s lithosphere extends from its surface to the liquid magma way down below.

What is the lithosphere?

The lithosphere is the solid outer layer of the Earth. This is the part that you, and I, and every other person on Earth stands on every day. But it’s not just us! This is the part of Earth that we build our schools, stores and homes upon!
 
Geologists examine the characteristics of the lithosphere and the processes that formed it. These processes are still continuing to shape it today. 

Earth’s ‘Spheres’

The lithosphere is one of the five great characteristics that make Earth what it is! The others are: the biosphere (living things), the cryosphere (frozen regions), the hydrosphere (liquid water), and the atmosphere (air surrounding). These five characteristics work together to make Earth the great planet that it is!
Atmosphere and hydrosphere.

Earth is made of many different ‘spheres.’ This is our atmosphere and part of the hydrosphere.

 
One product from this is pedosphere, which is in the lithosphere and made of dirt and soil. The cryosphere, atmosphere and hydrosphere can grind down the rocks in the lithosphere. Then the plant and animal remains from the biosphere mix with the ground rock to make soil!

What is the Relationship Between the Crust and the Lithosphere?

The crust, as well as the outermost layer of the upper mantle, is what the lithosphere consists of. These are bound together by the atmosphere and the asthenosphere. 

What is it made of?

The lithosphere is the most rigid, and rocky of Earth’s layers. The rocks that make up this layer are considered “elastic”, which means they are able to bend. Yet, they are not considered “viscous”, which is a thick and sticky liquid. But, the magma in the asthenosphere is viscous.
Magma.

Magma is a viscous liquid. Another is syrup, but I wouldn’t interchange the two. You’d melt your pancakes!

Interactions between the Lithosphere and the Mantle

There is a spot where the athenosphere and lithosphere come together. We call it the lithosphere-asthenosphere boundary. We will call it LAB for short. Geologists study the LAB to find the difference in ductility of the two layers. Ductility is a solid material’s ability to stretch under pressure. The asthenosphere is a lot more ductile than the lithosphere.
 
Both the elasticity and ductility of the lithosphere depend on the temperature, stress, and curve of the Earth. It’s separated into about a dozen rigid plates. We call these tectonic plates.
 
Scientists believe that what causes the movement of these plates is slow convection currents. You can find these far into the mantle. The convection currents are created by the interior being radioactively heated. They form columns of magma, called plumes.

Lithospheric Events and Plate Distribution

You’re probably wondering why the continents have not moved all around from this. Well, this is because the movement is so tiny, it almost can go unnoticed. The plates move at a rate of only several inches per year!
 
Some of Earth’s major events happen because of tectonic activity. These are events like earthquakes, volcanoes, mountain-building, and deep ocean trenches. 
 
There are seven major tectonic plates that make up the lithosphere. But there are many other minor plates too.
Map of tectonic plates.

A map of the Earth’s tectonic plates.

Temperature

Despite it being heated, the lithosphere is also the coolest layer of the Earth. Some scientists believe the radioactive heat has to do with the “plastic” mantle below it. It’s called plastic because it’s like the plastic we use every day. When it heats it can be shaped

Thickness

The lithosphere is really thick, sixty miles on average! If you were to drive through it, it would take you about an hour! 
 
There are two different types of lithosphere: oceanic and continental. Oceanic lithosphere is associated with Earth’s oceanic crust. It can be much thinner than the continental type. The continental type can go over 124 miles below Earth’s surface!  
Sand underwater.

Beneath the sand is thick oceanic crust.

 
Yet, at rift valleys and mid-ocean ridges, the lithosphere is as thin as the Earth’s crust. This is because the tectonic plates shift far away from one another. 
 
For more information, watch this video:
 

Other Great Resources: 

 
 
Written by: Lindley Lund.