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Castle Geyser is a cone geyser in the Upper Geyser Basin of Yellowstone National Park. It has the largest cone, formed by large geyserite sinter deposits, and may be the oldest of all geysers in the basin. Many eruptions of Castle start with little or no warning. A major eruption usually occurs every 9-11 hours.
The water shoots between 60-90 feet (18-27 m) and blasts for about 20 minutes. A noisy steam phase follows which lasts another 30-40 minutes.Image credit: NPS photo by Neal Herbert
