The Yellowstone region is one of the most dynamic seismic areas in the world—wracked by earthquakes, cracked by water boiling to the surface, and littered with the detritus of previous volcanic eruptions. Image circa 1985.
Yellowstone National Park is comprised primarily of high, forested, volcanic plateaus that have been eroded over – the millennia by glaciation and stream flow and that are flanked on the north, east, and south by mountains. Image circa 1985.
More than 200 million years ago, flourishing trees and vegetation covered much of this area of Northeastern Arizona. But volcanic lava destroyed the forest, and the remains were embedded into sediment comprised of volcanic ash and water.