The temperature of the asthenosphere begins at a little over 1,600 degrees Fahrenheit but does not rise above 6,700 degrees F. It lies beneath the lithosphere or crust of the earth and the more rigid part of the upper mantle.
The asthenosphere lies between 64 and 124 miles beneath the earth's surface but can plunge to 435 miles deep.
The heat found in the asthenosphere is high, but not high enough to cause the rocks in the asthenosphere to melt. Because of this, they are found in a solid but viscous state, which allows them to flow. Though it moves only centimeters per year, this ability to flow allows the asthenosphere to float the tectonic plates that make up the earth's crust.