How many layers are in the earth?
Within the mantle, there are also different layers or sub-layers.
The inner mantle (next to the outer core) is semi-rigid, and flows very slowly.
The asthenosphere (lower) part of the upper mantle flows and is where magma comes from in a volcano.
The top portion of the upper mantle (next to the crust) is rigid and rocky.
This rocky top portion of the upper mantle is often grouped with the crust and called the lithosphere.