It's important to note that the mantle is divided into two layers:

* Upper mantle: Extends from the base of the crust to a depth of about 660 kilometers (410 miles). It's mostly solid but behaves like a very viscous fluid over long periods.

* Lower mantle: Extends from 660 kilometers (410 miles) to the outer core at a depth of about 2,890 kilometers (1,795 miles). It's mostly solid and denser than the upper mantle.