Lobby > Exhibits > Why Geysers Erupt > Underlying Geology > Branded by a Volcano

Together the three caldera-forming eruptions at Yellowstone expelled enough ash and lava to fill the Grand Canyon in Arizona.

During the eruptions, volcanic ash covered much of the western half of North America. The ash was likely one foot (.33 m) thick within several hundred miles from Yellowstone and several centimeters thick farther away. Wind carried the lightest ash particles around the planet, probably causing a notable decrease in global temperatures.

Next | 1 > 2 | Next Section: Volcanic Comparison