Pressure-The force pushing on a surface divided by the area of the surface. (Earth's structure, interactive science book)
Basalt-a rock that is fine and dark.
Granite-a rock that is coarse and light-colored.
The oceanic crust is made of basalt. Almost all of the oceanic crust is basalt.
The continental crust is made of granite. But there a lot of other rocks.
The lithosphere is the first layer. It is 100 kilometers thick. It is a rigid and strong rock.
The asthenosphere is the second layer of the mantle. The rock here is not as rigid and can bend over time. It is also hotter.
The mesosphere is the third layer. It is rigid and very hot. It is also very stiff.
Just below the asthenosphere is the transition zone. The transition zone is part of the mesosphere.
The inner core is the same thing only it is under so much pressure it is solid. Scientist now believe that there might be some silicon, sulfur, and oxygen in the core as well.
How Geologists Learn About Earth's interior.
They also learn about our earths interior by analyzing the seismic waves.