Deuteronomy 32: 21-22
21 They have moved me to jealousy with that which is not God; they have provoked me to anger with their vanities: and I will move them to jealousy with those which are not a people; I will provoke them to anger with a foolish nation.
22 For a fire is kindled in mine anger, and shall burn unto the lowest hell, and shall consume the earth with her increase, and set on fire the foundations of the mountains.
The Holy Bible : King James Version. 1995 (Dt 32:21). Oak Harbor, WA: Logos Research Systems, Inc.

While the chapter progresses in End Time type punishments, hunger, burning, etc, for our purpose I stopped at verse 22. A Fire is kindled in his anger and will consume the earth with her increase and, "WILL SET ON FIRE THE FOUNDATIONS OF THE MOUNTAINS". Now I take Gods word as literally as possible, and I take nothing he says lightly. To my best estimation he is speaking literally of the earth, and the consuming fire, which is in the depths of hell, (scientifically referred to as the molten core of the earth, and notice this was spoken of before modern technology new the center of the earth was on fire), but this consuming fire is burning the foundations of the mountains. The foundations of the mountains, primarily the earths crust and mantle, I believe are continually growing hotter and thinner until a climax is reached where the mountain ranges are no longer supported by them.