A few dumb question about the earth?

Although the surface of the Earth is cool, it gets hotter as you go down. It is unbearably hot in some of our deepest mines and they are only around a mile down. Once you go down far enough, the Earth is made of molten rock - like the stuff that comes out of volcanoes. The centre of the Earth is about 12,000 miles down and it is exceedingly hot.