Old Faithful, Wyoming

Old Faithful was named by the Washburn expedition of 1870. They were impressed by its size and frequency. It is not the biggest or most regular geyser in Yellowstone but it is the biggest regular geyser. Furthermore, it has been erupting in nearly the same fashion throughout the recorded history of Yellowstone.  Old Faithful is a cone-type geyser. Its intervals range from 35 to 120 minutes, its duration is 1 1/2 to 5 minutes and its height is 90 to 184 feet.