Why is the temperature hotter the farther down you go in the earth? Is it because of the gravitational pressure?

Edited December 23, 201015 yr by Uri

It is primarlily due to the energy produced by nuclear decay.

Why is the temperature hotter the farther down you go in the earth? Is it because of the gravitational pressure?

 

Kind of. The Earth is hot for several reasons. Primarily, it is because of the energy left over from its formation, as all that gravitational potential energy was converted to kinetic and converted to heat (i.e., giant rocks crashing into one another). There is also leftover heat from friction as the Earth's heavier elements sink to the core and lighter elements rise. Plus, as you say, the pressure heating everything up as it compresses. None of these are a continual sources of heat, though, and in fact the Earth is gradually cooling off as it radiates infrared out into space. This is the main reason it's hotter the farther down you go. The outside cools first, and insulates the parts farther down.

 

Additionally, there is some heat generated from radioactive elements in the core and mantle, as cypress said.