OLD FAITHFUL

most famous, though not the highest, of all North American geysers, at the head of the Upper Geyser Basin in Yellowstone National Park, Wyoming, U.S. It was so named in 1870 by the Washburn-Langford-Doane Expedition because it seemed to spout faithfully every 6370 minutes. Under continuous observation, however, it has been found that the eruptions occur with some irregularity, with intervals varying from as much as 33 to 120 minutes. Between 3,700 and 8,400 gallons (14,000 and 32,000 litres) of hot water (204 F before eruption) plus billowing steam are ejected at one eruption. Its fountainlike columns reach heights of about 170 feet (52 metres) on calm, windless daysaverage height, though, is about 130 feet (40 metres)and stand for approximately four minutes. Geologists place the age of the geyser at 200300 years.