Learn about the volcano under Yellowstone National Park in this video from NOVA Digital. Old Faithful—the powerful geyser in Yellowstone that erupts predictably—results from magma superheating water below the ground's surface. In the magma chambers beneath Yellowstone, there is enough partially molten rock to categorize it as a supervolcano. Because of tectonic plate motion, the hot spot that is now under Yellowstone was once under a different part of the North American Plate. About 12 million years ago, the hot spot produced a massive volcanic explosion in what is now Nebraska; the fossilized remains of hundreds of animals have been preserved in ash from that explosion. This video contains segments originally filmed for NOVA: Making North America, but not included in the final broadcast. This resource is part of the NOVA: Making North America Collection.