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Sleeping Giant
Right now, an eruption is brewing in Yellowstone National Park. Sometime during the next two hours, the park’s most famous geyser, Old Faithful, will begin gurgling boiling water and steam.
(46) Old Faithful is not only a spectacular sight; it’s also a constant reminder that Yellowstone sits on one of the largest volcanoes in the world. If you’ve never heard of Yellowstone’s volcano, you’re not alone.
(47) . Yet it has erupted three times during the last 2 million years. And one of those eruptions spewed enough volcanic ash and other debris to blanket half the United States.
Yellowstone’s volcano is sometimes called a "supervolcano," or extremely large and explosive caldera volcano.
(48) . This supervolcano formed over a hot spot, an extremely hot area in Earth’s mantle. John Valley, volcano professor, said that as the crust moves across a hot spot, the hot spot melts a section of the plat