The Middle Yellowstone Valley from Livingston to Gardiner, Montana: A Microcosm of Northern Rocky Mountain Geology

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Route

Start point

Bozeman, MT

End point

Gardiner, MT (roadlog returns to Bozeman)

Roads

I-90, U.S. 89, Montana 540, Pine Creek Road, and other minor roads

Total distance

178.7 miles

Geology

Summary

The middle Yellowstone (Paradise) valley, between the Great Plains at Livingston and the edge of the Yellowstone volcanic plateau near Gardiner, is a complex palimpsest of lithology, structure, and surficial processes. It shares basement rocks with the continental interior, largely to the north and east; Paleozoic lithologies with the western interior, compressive tectonics with the Fold and Thrust Belt to the west; extension with the Basin and Range to the west and south; and Cenozoic volcanism and elements of its geomorphic evolution with much of the surrounding region. The geological exploration of this region serves as a microcosm of the evolution of the geological understanding of the American West.

Key Lithologic Features

  • Paleozoic, Mesozoic, and Cenozoic sedimentary rocks
  • Various glacial deposits (Wisconsinan/Pinedale age)
  • landslide deposits in the Yellowstone (Paradise) valley
  • Nelson and Armstrong Springs, northern Paradise Valley
  • several rangefront alluvial fans
  • Metamorphic basement rocks of the North Snowy Block, viewed from near Pine Creek
  • Hydrothermal features at Chico Hot Springs
  • Fossiliferous Miocene lacustrine rocks of the Hepburns Mesa Formation
  • Point of Rocks volcanic/intrusive center (Absaroka Volcanic Field)
  • Glacial deposits in Tom Miner Basin
  • Landslide deposits and lacustrine siltstones related to the Yankee Jim Landslide
  • Hydrothermal features at La Duke Hot Spring
  • Travertine deposits at Gardiner
  • Megaripples in flood bars near Gardiner
  • Devils Slide (steeply-dipping Cambrian through Cretaceous formations)

Structures

  • Various folds, faults, and range-front fault scarps
  • Cenozoic extensional faults on the east side of the Yellowstone Valley

Landforms

  • Yellowstone (Paradise) Valley
  • Gallatin Range
  • Beartooth Range
  • Hepburn Mesa
  • Tom Miner Basin
  • Yankee Jim Canyon

Other Features

Reference

Locke, W.W., Clarke, W.D., Custer, S.G., Elliott, J.E., Lageson, D.R., Mogk, D.W., Montagne, J., Schmitt, J.G., and Smith, M., 1995, The middle Yellowstone Valley from Livingston to Gardiner, Montana: A microcosm of northern Rocky Mountain geology: Field guide to geologic excursions in Southwest Montana , Northwest Geology, v. 24, p. 1-65.

Availability

Order from the Tobacco Root Geological Society. Go to the List of available TRGS publications for ordering information.