An eruption of Grand Geyser, the tallest predictable geyser in the world, occurs every 7 - 15 hours. A classic fountain geyser, Grand erupts from a large pool with powerful bursts rather than a steady column like Old Faithful. An average eruption lasts 9 - 12 minutes and consists of 1 - 4 bursts, sometimes reaching 200 feet (60m).
*Adapted from the NPS Old Faithful Area Trail Guide and the Old Faithful Area Interactive Map
Survey Date: March 8, 1999
Geographic Area: Firehole River Drainage
Thermal Region: Upper Geyser Basin
Thermal Complex: Grand Group
Ranger District Contact: Old Faithful District, Colleen Rawlings (307) 344-2701
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