Volcanic Springs

Geysers, Hot Springs,
Mud Pots, and Fumaroles

Upper Geyser Basin, Castle Group

The Castle Group encompasses only a few features around Castle Geyser. On its west side the old road between Old Faithful Area and Morning Glory Pool intersects the group, to the east Firehole River marks the border with Sawmill Group.

Castle Geyser is exhibiting one of the most massive geyserite cones worldwide. It is 3.7 m (12 feet) tall, 36.5 m (120 feet) in circumference at the base, and 6 m (20 feet) in diameter on top. Radiometric dating of the cone revealed an age of approximately 1000 years, far younger than assumed before, while the surrounding sinter shield turned out to be around 10,000 years old. The early explorers of Yellowstone were not only impressed by Castle's size, but also by the exquisite globular ornamentation all around the cone. Until 1880 visitors chipped off most of the geyserite nodules, leaving behind the plain surfaces we see today.
In contrast to White Dome Geyser or Lone Star Geyser the size of the cone actually goes along with the power of Castle's eruptions. Water jets may reach up to 30 m (100 feet) height. However, Castle's play and intervals are known to vary within broad limits. Most common are major eruptions, followed by a longer steam phase, at an interval of approximately 11 hours.

Castle Geyser, water jet:

Castle Geyser Yellowstone

Castle Geyser

Castle Geyser, steam phase:

Castle Geyser Yellowstone

Castle Geyser
At the base of Castle's huge geyserite cone sits Tortoise Shell Spring. It is constantly boiling and splashing a few feet high.

Tortoise Shell Spring:

Tortoise Shell Spring Yellowstone

Tortoise Shell Spring
Gizmo Geyser is another feature at the base of Castle Geyser. It plays from three major, crack-like vents, a small open pool, and a few minor openings. Intervals seem to be quite variable and it is also known to act as a perpetual spouter or to undergo longer periods of dormancy. The geyser's name sounds rather weird. It is said that around 1990, when geyser activity was new to this feature, somebody in a group of observers called it "little Gizmo", much to amusement of all, and the name stuck.

Gizmo Geyser erupting:

Gizmo Geyser Yellowstone

Gizmo Geyser
The small, unnamed spouter next to Gizmo shows significantly stronger play if Gizmo is not dormant.

Spouter next to Gizmo:

Spouter Yellowstone

Across the road from Castle Geyser the drop-shaped Shield Spring appears.

Shield Spring:

Shield Spring Yellowstone

Shield Spring Yellowstone
Past Castle Geyser a boardwalk branches off downslope to Firehole River and passes Crested Pool, a typical bubble-shower spring. A tragic accident happened at Crested Pool in June 1970, before the turn of the boardwalk in front of it has been secured by a handrail. Blinded by steam, a 9-year-old boy from New York stumbled into the spring, died in the 93 °C (200 °F) hot water, and sank out of sight before the eyes of his parents. His disintegrated body could not be recovered completely.

Crested Pool (roll mouse over picture):

Crested Pool Yellowstone

Crested Pool, Andy Hecht, Yellowstone
Next to the eastern corner of Crested Pool's observation platform Tilt's Baby shows up. Tilt Geyser, located right of it, is dormant since long time and its crater is all but invisible. In contrast, Tilt's Baby erupts every 4 - 6 hours up to 2 m (6 feet) high. Standing on the platform, it is easily possible to look vertically from above into the erupting geyser, but don't do it! You never know, how high the eruption will be (Edit: The observation platform has been relocated several feet away from the geyser in 2016, so the risk is eliminated).

Tilt's Baby, on the far left side. Tilt Geyser's obliterated vent is in center of the picture:

Tilt's Baby and Tilt Geyser Yellowstone

Tilt's Baby and Tilt Geyser Yellowstone

Tilt's Baby erupting on August 18th, 2017:

Tilt's Baby and Tilt Geyser Yellowstone

Tilt's Baby and Tilt Geyser Yellowstone
Near the end of the boardwalk from Crested Pool down to Firehole River little Dungeon Geyser (UNNG-CGG-10) lies almost hidden behind some small trees in downstream (western) direction. It is rather inconspicuous; so to find it for the very first time look for the feature across the river from South Scalloped Spring. The dungeon of Dungeon Geyser undermines a small sinter mound and exits at several openings. One of them faces east, two lie on the west side of the mound, another one towards Firehole River. Even if it would make sense, the name doesn't refer to the branched plumbing system, but to its position on "dungeon level" of Castle Geyser. Spotting one of the frequent eruptions needs sharp eyes since they are only inches high and the geyser is located several feet away from the boardwalk.

Dungeon Geyser, vents on the west side (roll mouse over picture to display vent on the east side):

Dungeon Geyser Yellowstone

Dungeon Geyser Yellowstone
Downslope, on the bank of Firehole River, lies a nice, but quiet and unnamed hot spring cone.

Unnamed cone downslope of Dungeon Geyser:

Unnamed cone near Terra Cotta Geysers Yellowstone

The bridge over the river provides a good view on the Terra Cotta Geysers a little bit farther downstream. They are encompassing at least five different geysers, named consecutively from Terra Cotta "A" to "E". Geyser expert and Xanterra manager Mike Keller even counted 9 geysers here. Most often of all, as to be seen on the first picture, Terra Cotta Geyser A is active at intervals of approximately 2 hours. It is known to erupt sometimes together with Terra Cotta E, to be seen on the far left side on the pictures.

Terra Cotta Geyser A erupting (roll mouse over picture to display eruption together with Terra Cotta E):

Terra Cotta Geysers Yellowstone

Terra Cotta Geysers Yellowstone

Terra Cotta Geyser D erupting on August 19th, 2015. The pool in center is Washtub Spring (Terra Cotta C):

Terra Cotta Geyser D Yellowstone

Terra Cotta Geyser D Yellowstone
Also on the south river bank, but 150 m northwest beyond the Terra Cotta Geysers, the perpetual eruptions of Spanker Geyser can be spotted.

Spanker Geyser:

Spanker Geyser Yellowstone

Spanker Geyser Yellowstone
Just in opposite direction (upstream) from the bridge Sprinkler Geyser is to be found next to the river downslope of Castle Geyser. It is best observed from a spot near Liberty Pool on the trail between Sawmill Geyser and Lion Geyser. Sprinkler is erupting very frequently and up to 3 m (10 feet) high.

Sprinkler Geyser:

Sprinkler Geyser Yellowstone

Sprinkler Geyser Yellowstone

 Back to top



Content and photos on this homepage are protected by law. You may save photos on your Computer, but it is not allowed to use them in any other case without permission of the author. If you want to use photos originated by the author, please ask. Please respect licence conditions of photos of third parties on this homepage.