Yellowstone’s Old Faithful

Historic photo of Old Faithful
Old Faithful in the 1960s
Winter Photo of Old Faithful courtesy of the NPS


One of the main, if not THE main attraction in Yellowstone National Park is the Old Faithful geyser.

It was named Old Faithful by the Washburn Expedition of 1870.  The expedition entered the Upper Geyser Basin after they had traveled down the Firehole River.  They coined the term “Old Faithful” for this particular geyser after having noted the regularity of the eruptions.

It is only under specific conditions that geysers like Old Faithful are formed.  This makes they relatively rare.  Pockets of underground water are superheated by the magma under the surface of the earth.  Pressure builds up and this eventually causes the water t to seek an escape route.  A  tunne l through which the water escapes has a content of volcanic rock which has a high silica content and this is what lines the escape tunnel.  Because of the rhyolite lining the tunnel can withstand the incredible heat and pressure that occurs during an eruption.

Old Faithful was the first geyser named in Yellowstone.  It erupts currently about every 91 minutes on average.  There is an app that you can download which will give you the approximate time of the next eruption.

The water that erupts from the geyser has  been measured at 204 degrees Fahrenheit but the temperature of the escaping steam can be hotter than 305 degrees Fahrenheit.

It has been said that in the early days of Yellowstone people would sometimes use the geysers to do their laundry.  Supposedly they would throw their clothes in to the geyser between eruptions and then wait patiently for their laundry to be shot back out of the geyser.  Reportedly the clothes came out very clean but wool items did not fare too well at those temperatures.

The interval between eruptions appears  to be getting longer.  In the 1960’s there was a 66 minutes average wait time between eruptions.  Today that has changed to approximately 91 minutes.  We can only speculate about the reasons for this change.  It may be due to earthquake activity in the area which can affect the water system structure below ground.  The water tables may have changed over time or perhaps human activity is the reason.  No one knows for sure.

There may well come a time in the future when Old Faithful will be no more than a memory and a  history lesson.  Come and see her while there is still time.