700,000 year old basalt lava flow

Lava Creek spills over the surface of a basalt lava flow that was emplaced about 700,000 years ago. Named after the falls, the Undine Falls Basalt erupted before Yellowstone's third caldera-forming explosive eruption that ejected the Lava Creek Tuff (named after Lava Creek) about 640,000 years ago. Scientists first distinguished the Lava Creek Tuff from the Huckleberry Tuff about 3 km downstream from the falls in the 1960s. This was the first clue that Yellowstone's history included more than one caldera-forming eruption.