Montana’s autumn is my favorite time of the year to do field work. Daytime temperatures are usually cool enough to encourage one to keep moving and the lighting is simply gorgeous. It is also one of the best times to visit areas in and around Yellowstone National Park (YNP) because most of the tourists have gone home. So no huge bear traffic jams or jostling for parking spots at the better known thermal spots in YNP and surrounding environs – it’s just a wonderfully introspective time for field forays. What follows are several photos that chronicle some of my fall wanderings in the greater Yellowstone area, both in terms of wildlife and geology.
Some of my favorite sightings in YNP are bison at any time of the year. But the autumn snows bring on the bison’s technique of using its head to clear snow away from any vegetative food source. The result of their snow-clearing activity is a snow-masked face.
And where the snow hasn’t stacked up much, the YNP bison calmly graze and occasionally congregate on a ridge line to watch what remains of the YNP visitor traffic.
Geological features in YNP take on new dimensions with the golden low and slanting light of autumn. I’ve spent much time re-photographing geologic features at all scales that seem to glow in this season’s light.
The fall staging areas of sandhill cranes in southwestern Montana are mesmerizing. Staging areas are those locations where cranes annually congregate during late September into October, spend several days foraging through fields for food, and eventually continue on their migration southward from Montana to Colorado and the southwestern U.S.. The staging area that I usually go to is near Dillon, Montana, where hundreds of cranes can be viewed.
As I said initially, it’s hard to surpass a Montana/YNP autumn!
Geologic field work is always fun, but especially so when it turns up something unexpected. Working on Eocene to Recent geology and vertebrate paleontology in the Gravelly Range, southwestern Montana promised to be enthralling because the volcanics, sedimentary units, and vertebrate fossils are at elevations of about 9,000 feet. But to come across extensive, unmapped calcareous spring deposits of probable Eocene age is topping off research efforts.
At this point, I’ll just say that our field team is still at work on the Tertiary spring deposits. We’ve found numerous leaf impressions including those of ginkgo, palm, metasequoia, Fagopsis (extinct member of Beech family), and alder – just to name a few. We’ve shown the plant assemblage collected to date to several paleobotanists, and, at least for age, their take is that the assemblage is probably latest Eocene in age, and bears many similarities to Florissant, Colorado fossil plant assemblages.
The spring deposits in the Gravelly Range are extensive, covering an area roughly 2 miles in length with deposits up to 120 feet in thickness. The springs are best characterized as travertine, although the spring systems’ edges contain clastic fluvial units and both the springs’ edges and pools have features such as plant impressions, root systems, and small travertine balls.
Because the Gravelly Range is so close to Yellowstone National Park, it is extremely interesting to compare its Eocene spring deposits to hydrothermal units at both the currently active Mammoth Hot Springs (which probably began its activity about 7,700 years ago), and to the fossil travertine found just north of Gardiner, Montana, that formed about 19.500 to 38,700 years ago (Fouke and Murphy, 2016: The Art of Yellowstone Science: Mammoth Hot Springs as a Window on the Universe).
The Gardiner travertine is fairly well exposed because it has been extensively quarried for several decades. Of interest for comparison are numerous plant impressions that occur within microterracettes. Fouke and Murphy (2016) suggest that these may be impressions of sage brush. A photo of the quarried wall with the plant impressions is shown below.
Other features in the Gardiner travertine, now partly covered by graffiti, include a quarry wall that shows terracettes and microterracettes that are outlined by darker lines within the travertine. These features are probably indicative of a proximal slope facies.
Jumping forward in time to the extensive spring deposits of Mammoth Hot Springs (just within the northeast park boundary of Yellowstone National Park), is mind boggling. As in any comparison with rocks as old as Eocene to active deposition, one realizes how much detail is lost over time. But it is still worthwhile to try to compare spring features, so I’ll show a few photos of the Mammoth Hot Springs that may match up with various features of the fossil springs.
Suffice it to say, that the upcoming field season should be a good one, with more work to be done on the Gravelly Range spring deposits. And – it’s always fun to get a trip in to Yellowstone!
Some winter days in Yellowstone National Park are so amazing with clear blue skies and sparkling snow that they just take your breathe away. Luckily enough, I just experienced several of these kinds of days which I packed full of cross country skiing, snowshoeing, and animal watching.
One of the groomed trails that held a good snow base until about early afternoon is the Blacktail Plateau Loop. The trail follows melt-water channels that are associated with “Retreat Lake”, which was formed by the Beartooth glacial ice mass blocking the lower end of the Grand Canyon of the Yellowstone during the Pleistocene.
The Tower ski trail provides access to the Grand Canyon of the Yellowstone area. A favorite stop of mine is the Calcite Springs overlook where the thermal springs lie south of the overlook, on the west side of the Yellowstone River and Pliocene/Pleistocene sediment and basalt are on the Yellowstone River’s east side.
A groomed ski trail also accesses the Upper Terraces of Mammoth Hot Springs. However, after a few days of spring-like temperatures, the snow was so melted back that I just used my snowshoes to trek through the icy slush. Some thermal features were still covered by snow and slush, but others appeared much more vibrant against the white snow/slush blanket.
Aphrodite Terraces lie a short way north of the White Elephant Back Springs:
My favorite thermal feature of the Upper Terraces is Orange Spring Mound. The spring is supported by a fissure ridge and is intermittently active. Because of its low water discharge and subsequent slow growth, it has built up a characteristic cone shape.
All in all, it was perfect wintertime fun trekking around in Yellowstone. Can’t wait to get back there when the bears come back out from hibernation!