Fall Fieldwork in the Greater Yellowstone Area

Sheepeater Cliff area, Yellowstone National Park. This area is named in honor of the Shoshones who lived in this area, The name specifically comes from their use the big horn sheep – hence the name “sheepeater”. Note the columnar basalt in the cliff area which has an age of about 0.5 million years.

Doing geology field work in the greater Yellowstone area during the fall is always an adventure. This is the time that animals and birds are on the move, so it’s a good opportunity to have interesting chance encounters. In my quest to understand the Eocene thermal springs of the Gravelly Range in southwestern Montana, I’ve spent time in the Yellowstone area hiking around thermal areas. The Artists Paint Pots, located a few miles southwest of the Norris Geyser Basin, appear to be a likely analogy for the Gravelly Range thermal strata. Of particular interest is the red staining that occurs in many meters of Gravelly Range thermal deposit strata. The red stained rocks are ubiquitous in the Red Hill and Middle Springs areas.

Red Hill in the Gravelly Range, southwestern Montana, contains many meters of red-stained, thermally generated Eocene strata.
The Middle Springs area in the Gravelly Range also contains several meters of Eocene red-stained thermally-generated rocks. It’s extremely easy to confuse these rocks with the underlying red-colored Triassic Woodside Formation strata.
Red-stained thermal deposits at Artist Paint Pots.
Blood Geyser thermal pools at Artist Paint Pots, Yellowstone National Park.

The Artist Paint Pots, especially the Blood Geyser, are well known for red-colored rocks that are produced by iron oxides precipitating out of the thermal waters and staining the surrounding rocks.

As I said earlier in this blog, doing fall field work in the greater Yellowstone area usually means exciting chance encounters with various animals and birds. Some encounters are a bit more exhilarating than others, but I did manage to photo-document some in between finishing up field work for the season:

Young grizzly loading up with food (only caraway roots and mice!) in the Tom Miner Basin, Montana.

Bull moose eating on Cottonwood trees near Ennis, Montana.

Immature bald eagle near the Jefferson River, Montana.
Redtail Hawk on irrigation pipe, near Sheridan, Montana.
Trumpeter swan family resting at – ironically, Swan Lake Flats, Yellowstone National Park.
Great Horned owl giving me the evil eye…
Sandhill cranes in-flight near the Ruby Mountains, southwestern Montana.