Temperatures in the Earth's mantle are as high as 4,000 degrees Fahrenheit at its furthest depth and as low as 1,600 F in its uppermost layer. The Earth's mantle is made up of extremely hot, dense rock that is constantly flowing and stretches 1,800 miles from top to bottom, making it the thickest layer on the planet.
The Earth's mantle sits directly on top of the Earth' hot core, which the mantle borders. It is the thinnest and outermost layer. The four layers that make up the Earth's mantle are the lower mantle, upper mantle, asthenosphere and lithosphere. The lower mantle borders the Earth's core and is hotter and more dense than the upper mantle, which sits below the Earth's crust.