Volcanic Springs

Geysers, Hot Springs,
Mud Pots, and Fumaroles

Monument Geyser Basin

Monument Geyser Basin is located approximately 600 m (650 yards) beeline west of the road from Madison to Norris, but on an elevation of 180 m (200 yards) above the road. The trailhead, a roadway turnout, is just south of the northernmost roadway bridge over Gibbon River in Gibbon Geyser Basin. Running in parallel to Gibbon River, the first third of the 1.7 km (1 mile) hike features only a gentle rise, but the remaining two-thirds are even steeper to reach the high-lying basin. On arrival you will find a lot of steam vents, acidic hot springs, and the strange elongated sinter cones of former spray geysers. Their spraying activity is mentioned in old reports, and scientists assume that the slender sinter structures have formed on the bottom of an ice-age lake. Since Monument Geyser Basin was significantly more active and quite popular in the late 19th and early 20th century, most cones had names, but these are nearly forgotten. The only names in use today are Monument Geyser, as the official name, and Thermos Bottle Geyser as the unofficial synonym for the last semi-active feature.

The trail leads you to an observation area marked-off by logs, where you have the best overview over the entire basin. Of course, the first look falls on the group of sinter formations for which Monument Geyser Basin is famous.

Sinter cones of Monument Geyser Basin, seen from the observation point:

Monument Geyser Basin Yellowstone

Monument Geyser Basin Yellowstone
Monument Geyser's 2.5 m (8 feet) tall cone stands out (literally!) due to its shape and steam plume. Significant spraying activity has gone for a long time.

Close-up of Monument Geyser / Thermos Bottle Geyser:

Monument Geyser Thermos Bottle Geyser Yellowstone

Monument Geyser / Thermos Bottle Geyser Yellowstone
The other sinter cones farther north seem to stand close together if observed through binoculars or a telephoto lens.

Close-up of sinter cones north of Monument Geyser:

Monument Geyser Basin Yellowstone

Monument Geyser Basin Yellowstone
However, in order to take a closer look on them it is not advisable to cross the basin on a direct route. Many fumaroles, springs, and sinter crust make the ground trappy. If you want to take a look or picture with the rough landscape of Gibbon Geyser Basin in background, you should go counterclockwise around the thermal area through forested land. Seen from north the sinter cones turn out to be well separated from each other.

Northernmost sinter cones: Trip Hammer (left) and unnamed cone seen from north:

Trip Hammer Yellowstone

Trip Hammer Yellowstone
A few feet south two sinter formations, called Sperm Whale (showing dorsal fin and blow) and Sunning Seal, appear.

Sperm Whale (left) and Sunning Seal (center):

Sperm Whale and Sunning Seal Yellowstone

Sperm Whale and Sunning Seal Yellowstone
Most springs are concentrated in center of the area, but the perpetual spouter GMGBNN001 is close to the edge near the northern cones. Already the murky, yellow water indicates that this is an acidic spring.

GMGBNN001:

Monument Geyser Basin Yellowstone

The southern part of the basin exhibits less features. One of them, called Dog's Head, is a further massive sinter cone.

Sinter cone "Dog's Head" south of Monument Geyser:

Monument Geyser Basin Yellowstone

Dog's Head Yellowstone
Even farther south a large fumarole / steam vent catches the eye.

Fumarole GMGBFM006:

Monument Geyser Basin Yellowstone


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