Volcanic Springs

Geysers, Hot Springs,
Mud Pots, and Fumaroles

Fountain Flat Drive, Upper River Group - east side of Firehole River

Between Lower River Group in the north and Upper River Group in the south there is a remarkable gap over a distance of approximately 200 m (220 yards) regarding the appearance of thermal features, especially larger ones. Entering the Upper River Group on the east side of Firehole River, numerous springs of all sizes show up on a belt of approximately 150 m alongside the river. Over 90 % of them are too inconspicuous to be of interest to non-scientific visitors, so only a small selection shall be presented here.

The vent of the northernmost regularly active geyser is so tiny that it is easy to miss if not just spouting. Blurble Geyser, as described by T. Scott Bryan, or Burple Geyser, as archived in the RCN database, lies within a triangle of small pools. It plays up to one foot high at an irregular interval.

Blurble Geyser, the tiny vent between LRNN559 (left), and LRNN560 (right), and beyond the grass patch. The spring in foreground is LRNN561:

Blurble Geyser Yellowstone

Blurble Geyser Yellowstone
LRNN552 is one of the few more striking pools in this section.

LRNN552:

Hot Pool Spring LRNN552 Yellowstone

Concerning the size of the pool and the height of the eruptions Brain Geyser surpasses Blurble Geyser only marginally. It is to be found 25 m upstream of Blurble.

Brain Geyser (left of center), LRNN542 (front), LRNN543 (right):

Brain Geyser Yellowstone

Brain Geyser Yellowstone
The next remarkable feature is Dark Pool (UNNG-RVG-5, LRNN530). Compared to the description by T. Scott Bryan, who mentioned a "blackish-green pool", Dark Pool has heated up and shifted to a blue state. We did not see one of its infrequent eruptions reaching up to 2.5 m (8 feet).

Dark Pool:

Dark Pool Yellowstone

Dark Pool Yellowstone
Armored Spring, a few feet south of Dark Pool, exhibits an extraordinary geyserite cover with bizarrely shaped openings. The pink coloration along the geyserite rim resembles of Ojo Caliente.

Armored Spring:

Armored Spring Yellowstone

Armored Spring Yellowstone
Unquestioned highlight of the Upper River Group is Fortress Geyser. It is officially called Conch Spring, but as with some other features in Yellowstone, the official name is not as catchy as the one in local usage. Fortress Geyser shows near perpetual spouting up to 3 m (9 feet) height.

Fortress Geyser / Conch Spring erupting and quiet (roll mouse over picture):

Fortress Geyser Conch Spring Yellowstone

Fortress Geyser / Conch Spring Yellowstone

Fortress Geyser runoff:

Fortress Geyser Conch Spring Yellowstone

Fortress Geyser / Conch Spring Yellowstone
At some distance upslope of Fortress Geyser two large, shallow pools are located in an area, which is designated as UNNG-RVG-6 by T. Scott Bryan. Obviously we were not lucky to catch a cycle of higher spouting activity.

LRNN431 (foreground) and LRNN425 (right in background):

LRNN431 and LRNN425 Yellowstone

LRNN431 and LRNN425 Yellowstone

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