The massive cone is a sign of old age. Eruption
after eruption, probably for thousands of years,
scalding water has deposited this silica mineral
formation. By contrast, Old Faithful's fledgling
cone may be only a few hundred years old.
Castle Geyser has dramatically changed its
surroundings. By flooding the area with hot,
silica-rich water, the geyser has devoured part
of a pine forest and turned it into a thermal
desert. Tree skeletons are entombed within
Castle Geyser's eruptions are predictable; two
per day are typically recorded.
Thomas Moran painted this watercolor in 1872.
Vandalism has since destroyed some of Castle
Geyser's original symmetry.
Walter Trumbull, a member
of the Washburn expedition,
sketched Castle Geyser in 1870.