Over the past 18 million years or so, this hotspot has generated a succession of violent eruptions and less violent floods of basaltic lava.
The oldest identified caldera remnant straddles the border near McDermitt, Nevada-Oregon, although there are volcaniclastic piles and arcuate faults that define caldera complexes more than in diameter in the Carmacks Group of southwest-central Yukon, Canada, which are interpreted to have formed 70 million years ago by the Yellowstone hotspot [REF].