The park’s website said Ledge has “erupted at regular intervals of 14 hours” in the past. “The geyser became inactive between 1979 and late 1993. It erupted on a fairly regular cycle of every four to six days in 1994 and 1995.”

Although studies of the park’s geothermal plumbing system are constantly undertaken by scientists to better understand the park’s subterranean connections, there is still much that is unknown.

“These are dynamic systems,” Hungerford said.

According to the website YellowstoneNationalPark.com, Ledge geyser was named by “J.E. Haynes in 1927 because of its position under a ledge of geyserite. When it is active it erupts from five vents. Before an eruption, one of the small vents fills with water, splashing begins and progresses into a powerful burst of water. The main jet arches at a 40 degree angle and jets out 125 feet. The other vents may also play for up to 30 or 60 feet high. The main eruption lasts 20 minutes and slowly subsides after two hours. There is a rushing sound which accompanies each eruption, and the steam phase roars and rumbles.”

Water near the geyser has been measured at 202 degrees, and drilling in the region has found water near 400 degrees. So it's no wonder Norris is one of the hottest and most acidic places in Yellowstone.