Upper Geyser Basin

The Upper Geyser Basin, approximately two square miles in area, contains the largest concentration and nearly one-quarter of all of the geysers in the world. A variety of thermal features exist here: spouting geysers, colorful hot springs, and steaming fumaroles. The Upper Geyser Basin is the home of Old Faithful, the most famous and celebrated geyser in the world. The 1870 Washburn Expedition camped near Old Faithful and discovered the geyser had frequent and regular eruptions over 100 feet. They dubbed the geyser Old Faithful. It erupts once approximately every 45 to 90 minutes, depending on the duration of the previous eruption. To be able to predict your own eruption of Old Faithful refer to appendix A on page 115