A part of my recent geological field work includes working on high elevation Tertiary strata in the Gravelly Range, southwestern Montana. The Gravelly Range is located in southwest Montana, about 10 miles southwest of Ennis, Montana. For some background on this area and what my field work is about, see an older blog that I posted at Geopostings.
So – now that one field season is done and field data compiled, both my co-worker, Don Lofgren and myself have interpreted some of our data. We recently outlined our work at the Geological Society of America’s (GSA) Rocky Mountain section meeting in Calgary. Alberta. The abstract from our session is given below as well as the poster itself in both a jpeg format and as a link to our GSA presentation.
“Tertiary strata exposed in four high elevation areas in the south-central
Gravelly Range yield significant assemblages of Late Eocene to Oligocene
mammals. The thickest stratigraphic sections of Tertiary strata are in the
Lion Mountain-Black Butte area. The Lion Mountain section age is based
primarily on American Museum of Natural History collections; the lower
part of this section is Duchesnean-Chadronian (39-33 Ma) and the
uppermost beds are Whitneyan (32-31 Ma). Age of the basal part of the
Black Butte section is Duchesnean-Chadronian based on Harvard Museum of Comparative Zoology collections. Recent collections that include Miohippus indicate a probable Orellan age for uppermost exposures. The Tepee Mountain section is notable for abundant brontothere remains and is probably Duchesnean-Chadronian (approx. 39-33 Ma). The Rapamys site is the oldest vertebrate locality and is late Uintan to early Duchesnean (42-38 Ma) based on recently recovered specimens of Rapamys, Protoreodon, and Lycophocyon.
The Tertiary strata in this part of the Gravelly Range include fluvial, aeolian, and tufa deposits that are most likely mainly associated with localized Oligocene volcanism. The Lion Mountain section is about 270 meters in thickness; the lower half of the section is largely aeolian, with fluvial units comprising much of the upper section. Based upon age data, the 140 meter Black Butte section correlates to the lower 50-70 meters of the Lion Mountain section. The basal 20 meters of the Black Butte section contain some fluvial features, but much of the remaining section is largely aeolian in origin. Paleosols and extensive burrowing also occur within the Black Butte section. Stratigraphic section thickness decreases rapidly away from the Black Butte-Lion Mountain area, with section thicknesses of about 20 meters for the largely aeolian Rapamys and Tepee Mountain sections. Tufa deposits are located along the west-central edge of the Gravelly Range where they are associated with previously mapped thrust faults. Leaf imprint assemblages of Eocene-Miocene age are contained within these tufas. Strata previously mapped as Upper Cretaceous-Paleocene Beaverhead Formation are now variously reassigned to the lower Cretaceous Kootenai Formation, southwestern Montana Cenozoic Sequence 2, and diverse Quaternary units.” From: Abstract from Geological Society of America Abstracts with Programs. Vol. 49, No. 5 doi: 10.1130/abs/2017RM-293156.
The poster presented at the 2017 Rocky Mountain GSA is available below as a jpeg and at GSA as a pdf.
The Association for Women Geoscientists (AWG) published their first geology field trip guidebook in late 2016 and it is now available for sale to the general public. This guideboook is a collection of geology road logs, associated geological information, and local cultural history of areas within the Canadian Rockies and the Alberta Badlands. The following text is a brief summary of the guidebook:
“TECTONICS, CLIMATE CHANGE AND EVOLUTION – SOUTHERN CANADIAN CORDILLERA: Road Log and Accompanying Narratives From: Calgary – Lake Louise – Icefields – Field – Revelstoke – Fernie -Dinosaur Provincial Park – Calgary”, published by the Association for Women Geoscientists, 2016.
This field trip guidebook is written by Katherine J.E. Boggs and Debra L. Hanneman, and edited by Janet Wert Crampton and Stephanie Yager. It is the AWG’s first fully published field trip guidebook and is a field-tested guide from their two-week 2014 field trip through the Canadian Rockies and Alberta’s Badlands area.
The guidebook is a 209-page geology tour through many of the well-known parts of the Alberta Canadian Rockies, including the Front and Main Ranges of the Canadian Rockies and the Columbia Icefields. The Burgess Shale’s Walcott Quarry, the Okanagan Valley vineyards, and the Rocky Mountain Trench are trip highlights for geo-tours in British Columbia. The field trip guidebook ends with a geology tour of the Crowsnest Pass area on the British Columbia/Alberta border, and with field stops in Alberta’s Dinosaur Provincial Park and at the Royal Tyrrell Museum, Drumheller, Alberta.
The field guide is printed on double-sided 8.5″ x 11″ pages with the guide cover on 100 lb paper and the text on 80 lb paper. It has black wire-o binding and a clear acetate front and a black acetate backing for improved field durability. The guidebook’s cost is $55 USD (which includes shipping), and can be purchased at the AWG online store or by phoning the AWG main office at 303-412-6219.
I love living in Montana, but some days are just better than other days. This is one of those “better” days. This morning I checked my media feeds to learn that more than forty Montana writers have come together to write about their support for protecting our public lands and to also endorse Montana’s Special Congressional election Democrat candidate Rob Quist’s position on this issue.
The push for the transfer/sale of public lands, particularly federal public lands, has reared its ugly head again in many forms across the western U.S.A.. This is an issue that needs to be met head on by all of us who value our public lands.
The 24-page tabloid writers’ anthology will be part of three Montana state newspapers this Sunday. Copies will also be handed out at this weekend’s Quist events with Sen. Bernie Sanders in Missoula and Bozeman. The anthology is also available as a pdf download at the “We Take Our Stand” website.
A nodosaur, approximately 112-110 million years old, was found in the Alberta oil sands March 21, 2011. The dinosaur is basically a mummy, with fossilized skin and gut contents intact. Luckily, the heavy-equipment operator and his supervisor knew that what was being unearthed at Suncor’s Millennium Mine that amazing day in March was unusual. It was so remarkable a find that they notified the Royal Tyrrell Museum in Drumheller, Alberta, and museum workers quickly came up to the mine to collect it. After 6 years and over 7,000 hours of preparation work, the dinosaur is now on exhibit at the Royal Tyrell Museum in the newly opened Grounds For Discovery exhibit. For more information on the discovery, check out National Geographic’s article – The Amazing Dinosaur Found (Accidentally) by Miners in Canada.
Scientists from the Universities of Bristol and Cambridge used a drone to video an eruption of one of Guatemala’s active stratovolcanoes, Volcan de Fuego. The volcano is part of the Central America volcano arc and is one of three large stratovolcanoes close to Guatemala’s former capital, Antigua. The drone flew 3,700 m over Volcan de Fuego to get the video footage.
I took a break from writing a paper on Tertiary volcanic tuffs in southwestern Montana a few days ago to go on our yearly steelhead fishing trip on the South Fork of the Clearwater River in Idaho. Steelhead are amazing fish in that they are ocean-going rainbow trout that spend two years in the ocean, and then swim back into Idaho rivers like the Clearwater, Snake, and Salmon. Eventually the steelhead reach these rivers’ upper stretches for their spawning grounds. On the South Fork, steelheads are considered as “B-runs”, which are a mix of both native and hatchery fish.
This year’s fishing adventure was marked by extremely high water levels. We usually fish at an area called the Hog Hole, a part of the South Fork that is armored by large boulders – and as an Idaho Fish and Game person told me – is an impressive velocity barrier to upstream fish migration. Fisherman typically occupy many large boulders that are scattered across the river at this location. That wasn’t possible during our fishing trip as the high water limited us to standing on only the rocks along the river’s banks.
The other impressive part of this annual fishing trip is that it takes place basically along the Western Idaho Suture Zone (WISZ). The WISZ, as noted by Fleck and Criss (2004)…
represents the boundary between crust overlying Proterozoic North American lithosphere and Late Paleozoic and Mesozoic intraoceanic crust accreted during Cretaceous time (Fleck and Criss, 2004).
The Digital Atlas of Idaho gives a good overview of the WISZ and accreted terrains. For the South Fork of the Clearwater, the Digital Atlas also breaks down the Idaho geological map by county, with the stretch that we fish lying in Idaho County. According to the Idaho County geological map, the Hog Hole sits on the west side of the suture, in accreted terranes that are partially covered by Tertiary Columbia River basalts (17.5 million to 6 million years in age) and intruded by Jurassic to Cretaceous (160 million to 120 million years in age) felsic plutonic rocks. Glacial sediments overlie these older rocks, particularly in the upper part of the South Fork drainage. The juxtaposing of all the varied geology does add another level of enthusiasm for the annual fishing expedition!
A very large crack is forming in the Larsen C Ice Shelf on the Antarctic Peninsula. The crack is up to 1,500 feet wide and will most likely generate one of the largest icebergs on record. Only 6.4 miles of ice are keeping the ice sheet from calving off an iceberg that is basically the size of Delaware. Researchers who have been studying the ice melt (Project MIDAS) estimate that although the exact timing of the calving event in unclear, it could occur easily within the next few months. In fact, scientists noted that the crack spread another approximately six miles during the second half of December 2016. From January 1st to January 19th, the crack expanded again, and now only 6.4 miles of unbroken ice remains. Once the calving event occurs, scientists are concerned that it will destabilize the Larsen C ice sheet to the point of its disintegration.
British Antarctic Survey (BAS) recently captured the following video footage of the immense crack in the Larsen C Ice Shelf:
Geoawesomeness got my attention today by featuring a You Tube video done by Vox folks a few months ago. The Vox video points out that basically all world maps are wrong in how projections of land masses are variously shown. Aleks Buczkowski from Geoawesomeness gave a lead-in to the Vox video in his posting on it by saying:
Projecting a round surface of the Earth on a flat surface is not an easy task. Scientists are trying to find an optimal way to do it for centuries. In fact the most common map projection that we use almost everyday in Google Maps and other mapping services, has been introduced in 1569 by Gerardus Mercator.
The video from Vox does help to explain the intricacies of map projections and is really worth watching:
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!
Much of my research has been focused on Cenozoic sequence stratigraphy of continental basin-fill in southwestern Montana. This approach to the stratigraphy of continental deposits has facilitated correlation of stratigraphic units both within and among the various basins of this area. I recently gave a talk about my work in this area at Montana Tech of the University of Montana. Here’s the You Tube version of my talk: