Old Faithful is the name of the world’s most famous geyser. Geysers are springs that spout columns of hot water and steam into the air. Old Faithful lies in northwestern Wyoming, within Yellowstone National Park. The geyser’s name refers to the regular, reliable timing of its eruptions.
Most of Yellowstone’s landscape was created by volcanic eruptions about 600,000 years ago. A large mass of molten rock still lies beneath the surface of the park. This rock, called magma, provides the heat for the park’s geysers and hot springs. Yellowstone has more than 300 active geysers and thousands of hot springs.
In most years, Old Faithful erupts, on average, about every 90 minutes. The actual intervals between eruptions vary from about 30 to 120 minutes. Most eruptions are 120 to 150 feet (37 to 46 meters) high. Each eruption usually lasts from 1 1/2 to 5 minutes. Observers began documenting the geyser’s activity in the late 1800’s. Since that time, Old Faithful has rarely missed an eruption.
Old Faithful is not the largest geyser at Yellowstone. But among the park’s large geysers, it has the most predictable eruptions. Predictions are based mainly on the duration and volume of previous eruptions.
Fur trappers explored the Yellowstone area beginning in the 1830’s. They told stories of spouting geysers and hot springs. In 1870, members of an expedition led by General Henry Washburn gave Old Faithful its name. The geyser has also been called “Eternity’s Timepiece” because of the predictable nature of its eruptions.
See also Geyser ; Yellowstone National Park .
