Understanding lithosphere definition can help you gain a better understanding about the world we are living in. After all, our Earth comprises of different geographical elements having its own significant roles and importance for life and its existence.
Lithosphere Definition and Its Overall Basic Facts
So, what is the definition of lithosphere, anyway? Lithosphere is the rocky and solid part of the Earth, also known as the Earth’s crust. It is called as the Earth’s crust because it is basically the skin of planet Earth. As you are well aware of, the skin is the outer layer so when we are talking about the Earth’s skin, we are talking about the many layers of the lithosphere.
Now that you are well aware of lithosphere definition, do you know the origin of the word? It is taken from Greek words, lithos (rock) and sphere. Lithosphere itself isn’t only consisting of rock formation but also the rigid, dense, and cool part underneath the upper layer. The lithosphere layer usually extends to 44 miles or 61 miles underneath the surface – around 70 km to 100 km. The rigid and cool section is said to float on the non-rid, partially melted, and warmer materials below. So, if you see the series of layers from top to bottom, you will see the rigid and solid layer, followed by the dense and cool layer which is floating right above the melted and warm material. When we are talking about the lithosphere temperature, we are talking from the cooler to warmer areas, from the exterior to the interior.
As it was mentioned before, there are different layers of the lithosphere with different temperature and depth. The outermost one is the crust with different variations of thickness. Under continents or lands, the thickness can reach 35 km or 22 miles, sometimes going deeper to 60 km or 37 miles under the mountainous areas. Under oceans, however, the crust can only have 5 km to 10 km of thickness (it is about 3 miles to 5 miles).
Right under the crust, there is the also rigid and solid layer but it is in between cool and warm. It comes with the thickness of 50 km to 100 km or around 31 miles to 62 miles. This is crucial layer because it combines the rigid rocky materials with crust aspects, making up for the definition of lithosphere itself.
And right beneath this layer, the lithosphere temperature can reach 1,000 degrees Celsius (or around 1,832 degrees Fahrenheit). In geological field, this temperature is considered warm enough for the rocky materials to flow or move when there is enough pressure. In this layer, it would be quite common to find molten material. It may not be much, only around 10%. This area is often called as the asthenosphere.
Now that you are already familiar with lithosphere definition and its description, what can you learn from it? As you can see, the asthenosphere is the warmest layer between the three. Since the lithosphere temperature is the highest, the materials within it are not solid as they all flow and move. The layer above it can’t stay fixed so it looks like the materials are floating. It is only the outermost layer is the most solid one.
Because the second layer isn’t solid or fixed (because of the materials are moving around), the plates are often hitting each other. If you are familiar with the so-called tectonics plates, this is the reason why the plates are jostling against one another. When the tectonics plates happen, you experience continental drift, volcanic activity, and earthquakes. This is the basic explanation about the definition of lithosphere and why the earthquake happens.
As you can see, our planet Earth has a complex structure consisting of many elements, including layers of the lithosphere. Now that you already know about lithosphere definition and the explanation of natural phenomenon, you now understand why those natural events are happening.