 The Snake River Plain is a volcanic province that was created by a series of cataclysmic caldera @-@ forming eruptions which started about 15 million years ago . A migrating hotspot thought to now exist under Yellowstone Caldera in Yellowstone National Park has been implicated . This hot spot was under the Craters of the Moon area some 10 to 11 million years ago but ' moved ' as the North American Plate migrated southwestward . Pressure from the hot spot heaves the land surface up , creating fault @-@ block mountains . After the hot spot passes the pressure is released and the land subsides . 
