Solution :
Crust
In the field of geology, the crust may be defined as the outermost solid shell of a planet. It forms the topmost outer hard layer of the earth surface. Earth has three layers. They are the crust, mantle and the core.
When we go deeper and deeper inside the earth's crust, the temperature rise. In the crust, on the surface of the earth, the temperature is normal and is atmospheric. As we go deep down the core, the temperature rise and it is highest at the core where all the rock and the iron is in the form of the molten lava.
According to the Geologist, beneath the earth's crust, for every mile we go inside the temperature rises by 15 degree Fahrenheit.