The upper mantle and lower mantle together form the mantle, which is the layer of Earth between the crust and the core.

Here's a breakdown:

* Upper Mantle: The uppermost part of the mantle, extending from the base of the crust to a depth of about 410 kilometers (255 miles). It's largely composed of solid rock, but it behaves more like a very viscous fluid over geological time scales. This is where tectonic plates move and earthquakes originate.

* Lower Mantle: The lower part of the mantle, extending from the bottom of the upper mantle to the top of the core at a depth of about 2,890 kilometers (1,800 miles). It's primarily composed of silicate minerals and is much denser than the upper mantle. The extreme pressure at these depths causes the rock to behave more like a solid.

Together, the upper and lower mantle represent the majority of Earth's volume.