The Mantle.
The Mantle is very thick and hot. It starts 30 KM. down. The upper Mantle is solid rock. It is about 1000C. The Mantle is the largest layer of earth. The mantle is the 2nd layer of our earth. The size of the mantle is about 2,890km and the mantle is the thickest layer of all of the layers of the earth.