The Mesa Falls eruption
Yellowstone erupts a second time, forming the Henry's Fork Caldera.
- When
- Known to
- ± 20 thousand years
- Era
- Early Pleistocene, Quaternary
About 1.3 million years ago the Yellowstone hotspot produces its second major caldera eruption, ejecting roughly 280 cubic kilometres and forming the Henry's Fork Caldera in Idaho. It is the smallest of the three Yellowstone supereruptions, but still an order of magnitude larger than any eruption in recorded human history. The three eruptions are spaced roughly 800,000 and 660,000 years apart, a spacing often misread as a schedule.