Where does heat to form geysers in Yellowstone come from?
The heat comes from a buried magma ( molten rock) chamber less than 2km below the surface. The magma is the source of much of the volcanic rocks in Yellowstone. The major eruption which formed the Yellowstone caldera was about 600,000 years ago and spread wind born ash as far away as Louisiana. The area is considered by some geologists to have potential for additional eruptions, though, there have been none during recorded time.
