Echinus Geyser in Norris Geyser Basin, YNP.
This geyser exhibits irregular behavior, sometimes erupting regularly for months, and then ceasing altogether. Echinus is a rare acidic geyser, with a mixed water rich in both sulfate and chloride. Temperature is measured in the outlet channel that carries much of the erupted water. Rapid temperature increases in geyser outlet channels typically reflect increases in flow due to eruptions of the nearby thermal feature.