There is no soft layer of rock in the mantle. The mantle is the layer of the Earth that lies between the crust and the inner core. It is composed of solid rock, mostly peridotite, that is very hot and under high pressure. The temperature of the mantle ranges from about 1,000 degrees Celsius at the top to about 3,700 degrees Celsius at the bottom. The pressure of the mantle ranges from about 100 MPa at the top to about 140 GPa at the bottom.