The second (Mesa Falls) was 800,000 years later. The third, centred on Lava Creek Tuff and dated to some 650,000 years ago, defined much of the region’s terrain as it is known today. But the ...

The second (Mesa Falls) was 800,000 years later. The third, centred on Lava Creek Tuff and dated to some 650,000 years ago, defined much of the region’s terrain as it is known today. But the ...

Map showing extent of ashfall from eruptions. The Yellowstone Caldera formed over 600,000 years ago from the Lava Creek Tuff eruption, which was measured on the Volcanic Explosivity Index as an 8 ...