Photographs of Upper Geyser Basin, Yellowstone National Park

Castle Geyser is notable both for its large and relatively frequent eruptions, and the huge sinter cone surrounding its vent. The white cone is about ten feet high, sitting on a wider mound also formed of geyserite, together comprising the largest sinter formation in the Upper Geyser Basin, established over several millennia, if not longer. The geyser was amongst the first in the area to be named, in 1870. Eruptions have changed in nature over the last century but currently consist of a water plume up to 90 feet tall for around 20 minutes, followed by a stream phase of about half an hour. 10 to 12 hours pass between eruptions. Castle is one of five geysers in the basin for which activity is predicted.

Back to map of the Upper Geyser Basin

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