Initial Publication Date: January 13, 2025

FIELD GUIDE: Red Lodge to Cooke City, Montana--The Beartooth Highway

David Mogk, Professor Emeritus, Dept. Earth Sciences, Montana State University

(Download to your mobile device or print the PDF of this Field Guide Beartooth Highway (Acrobat (PDF) 5.4MB Dec31 24) for information about Beartooth Country when traveling in areas where there is no cell or wi-fi access).

Overview

The next leg of this field guide is from Red Lodge to Cooke City, MT, on US Highway 212 on the Beartooth Highway. The USFS describes the Beartooth Scenic Byway-All American Road. The US Department of Transportation Federal Highway Administration provides this review of the many challenges in the history of construction and maintenance of this highway: An Orphaned Highway. This field guide is a summary of the geologic stops more completely described in the 2024 Tobacco Root Geological Society Field Conference field guide: Mogk et al., (2024), Precambrian Rocks of the Eastern Beartooth Mountains (Acrobat (PDF) 7.6MB Dec11 24). Additional information on campgrounds and interesting trails to access areas adjacent to the Beartooth Highway are also provided.


Starting in Red Lodge, MT:

  • Intersection Highways MT 78 and US 212, north side of Red Lodge; mileages posted below begin at this point.
  • 2 miles; USFS Red Lodge Ranger District HQ; check here for latest information about road closures, other restrictions (e.g., fire danger), and access to trails, campsites, and day use areas.
    • The USFS South Beartooth Front Motor Vehicle Use Map (Acrobat (PDF) 743kB Dec24 24) identifies authorized motor vehicle use for West Fork Rosebud Creek, East Fork Rosebud Creek, West Fork Rock Creek (numerous campgrounds), and Rock Creek area (south of Red Lodge).
  • ~11 miles; Lake Fork Trail--a popular trail that is 9.5 miles to Sundance Pass with a vertical gain of 3800 feet, and loops back towards Red Lodge on the West Fork (Rock Creek) Trail (11 miles from Sundance Pass). Download the Lake Fork and West Fork Trail Maps. The Lake Fork valley separates the Silver Run Plateau to the north and Hellroaring Plateau to the south--both underlain primarily by the extensive 2.8 Ga magmatic rocks with inliers of older high-grade metamorphic rocks.
  • ~13 miles; Parkside, Limber Pine, and Greenough Lake Campgrounds (pit toilets and water available); Download the Hellroaring Plateau and Glacier Lake Trail Guides
    • Rock Creek--Drive ~ 8 miles to the end of Rock Creek Road through the beautiful glacier-sculpted U-shaped valley.  Hike 2.2 miles to Glacier Lake. This road can be quite rugged with potholes and boulders, so driving street vehicles is not recommended (use high-centered, 4 wheel drive vehicles)
    • Hellroaring Plateau--The Hellroaring Road is accessed ~1 mile past the campgrounds and is an abandoned haul road for the chrome mines that were in operation during WWII.  It is a very primitive road and 4 wheel drive or ATV transit is required to drive to the trailhead at the edge of the Hellroaring Plateau.  The road report as of August 2024 is that the road is now closed due to a washed out culvert due to the 2022 flood event.  A geologic description is included here because of the significance of this site in unraveling the Archean geology of the Beartooth Mountains, and its recognition in the IUGS First 100 Geosites.  Key features of this area are: 1) Km-scale sequences of high-grade metamorphic supracrustal rocks that include quartzites, pelitic schists, banded iron formation, and amphibolite/granulite mafic rocks that are tectonically intermixed with varieties of older "gray gneisses" (3.5-3.2 Ga old; 2) these "old rocks" occur as pendants and screens that have been intruded by voluminous 2.8 Ga granitic rocks that occupy most of the Hellroaring and Silver Run Plateaus; and 3) numerous small chromite deposits are scattered across the Hellroaring Plateau, originally mapped and described by James (1946) in USGS investigations. The sequences of the "old rocks" are well-exposed on the road just above the bridge that crosses Hellroaring Creek and at the edge of the Plateau near the trail head. Quartzites from this location preserve a small population of zircons that have been dated as old as 4.0 Ga. (See view from the  Rock Creek Vista, described below).
  • 15.5 miles; Stop 1 Lower Quad Creek Outcrop.  Park at the pullout (highway right, past the guard rail) and walk back to the outcrop ~300 yards; be extremely careful walking on the side of the road as there is a blind corner for traffic. This outcrop is significant because it includes: a) layers of old gray gneisses of tonalite composition dated at 3.5-3.2 Ga; b) minor layers of high grade pelitic schists (garnet-sillimanite-cordierite-biotite) and amphibolite to granulite grade mafic rocks; c) interlayered 2.8 Ga igneous intrusive rocks related to the Long Lake Magmatic Complex (tonalite to granite in composition); and d) a cross-cutting 2.5 Ga mafic dike.



  • ~21 miles; Stop 2 Upper Quad Creek Outcrop. Park along guard rail or at bend in the road (see truck in picture). This outcrop is another enclave of "old metamorphic rocks" surrounded by younger 2.8 Ga granitic rocks.  Rock types are prominent outcrops of quartzite, banded iron formation, pelitic schist (largely smeared out along ductile shear zones), mafic amphibolite/granulite, and felsic gneisses. The outcrop to the west is the enclosing 2.8 Ga granitic gneiss that has large phenocrysts of plagioclase colloquially referred to as the "popcorn gneiss". 
    • At the bend in the road is a large, funnel-shaped igneous body that is the mafic Quad Creek Metanorite which has large crystals of orthopyroxene and overprinting amphibole and biotite. Crystallization occurred at approximately 2.79 Ga, coinciding with the waning stage of LLMC plutonism. 



  • 22.3 miles; Stop 3: Rock Creek Vista (pit toilets available; large parking area):  This is the classic view of the Rock Creek U-shaped glacially-carved valley. Directly across Rock Creek, the Hellroaring Road is visible. The abandoned chrome mines are visible on the lip of Hellroaring Plateau (dark areas). Outcrops of the layered "old" enclaves of gneisses and metasupracrustal rocks are on the cliffs in the middle ground; the voluminous 2.8 Ga Long Lake Magmatic Complex are the lighter rocks that dominant the bedrock across Hellroaring Plateau, Silver Run Plateau, Mt. Rearguard on the skyline.
  • Line Creek Plateau/Wyoming Creek, east of the Beartooth Highway:  
    • Numerous trails provide access to the Line Creek Plateau area, from just south of Red Lodge near Mt. Maurice to the Wyoming state line. Line Creek Plateau Trails  The underlying bedrock are the granitic gneisses related to the LLMC, and also numerous bodies of the "Laramide Porphyry" areas described by Cunningham et al., (2024).   These trails include: Face of the Mountain Trail (#7), Mt. Maurice Trail (#6), Corrall Creek Trail (#9), and Robertson Draw Trail (#5).
    • Exploratory oil wells were drilled on the Line Creek Plateau in 1985-86 looking for a structural trap created by crystalline rocks thrust over Mesozoic sedimentary rocks on the Beartooth Fault. Omar et al., (1994) used core from these wells  to conduct apatite fission track analysis to determine uplift history on the Laramide fault: "Amoco Beartooth No. 1 well (spudded at 1,904 m a.s.l.), drilled 7 km south of Red Lodge, Montana, in 1985 and 1986, penetrated the following sections: (1) 540 m of crystalline rocks in the upper plate of the Beartooth overthrust, (2) 76 m of deformed rocks in a shear zone representing the thrust surface, and (3) 1,350 m of sedimentary rocks representing the lower plate, primarily in the upper limb of an overturned syncline. These sedimentary rocks range from the Sundance Formation (Jurassic) just below the shear zone to Cody shale Cretaceous) in the axis of the syncline." 
    • Omar et al., (1994) determined there was 7 to 12 km of uplift of the Red Lodge corner of the Beartooth block since early Paleocene time. "This amount of uplift occurred in two stages, with an intervening mid-Tertiary period of tectonic quiescence. The latter was a period of either (1) Oligocene and/or Miocene deposition or (2) tectonic quiescence. Uplift of 4 to 8 km occurred during the first phase of cooling, which lasted from early Paleocene time (61 Ma) to early Eocene time (52 Ma). During the second phase, which began in late Miocene-early Pliocene time and continues to the present day, about 4 km of uplift occurred."
  • ~24 miles, Stop 4 Top of Quad Creek, large turnout along the guardrail has ample parking for multiple vehicles; This stop provides another exceptional view across Rock Creek to the Hellroaring Plateau. Additional points of interest:
    • This is the top of the Quad Creek Metanorite mafic body.
    • On the east side of the road, there is an abandoned, reclaimed ore road to chromite prospect pits. Walk north ~1/4 mile to a series of surficial prospect pits that are largely reclaimed. The tailings have good samples of the host ultramafic rocks (now largely serpentinized, with associated talc and tremolite alteration), and there are still some podiform chromite samples that can be found.
    • Continuing north another quarter mile, there is a big exposure of the Laramide Porphyry, first described by Rouse et al., (1937), mapped by the Columbia group of Poldervaart students across the Beartooth Plateau, and most recently described by Cunningham et al., (2024).  This unit is remarkable for cm-sized phenocrysts of orthoclase (potassium feldspar) crystals with well-developed Carlsbad twins. These crystals weather out of the porphyry and beautifully formed terminated crystals can easily be collected.
    • The next 1-2 miles, on the east side of the road on the cliffs above Wyoming Creek, there is another band of high-grade metasupracrustal rocks including quartzites and sillimanite-garnet schists that were mapped by Rowan (1969).
  • 29 Miles, Stop 5 Beartooth Ski Area, ample safe parking: A premier photo opportunity. Spectacular views of the high Beartooth Pleateau Block, upper Rock Creek towards Glacier Lake, Twin Lakes.  The bedrock geology is the voluminous body of the 2.8 Ga Long Lake Magmatic Complex, felsic igneous rocks of tonalitic (Na-rich) to granitic (K-rich) igneous rock. Does this landscape and rock suites look like modern magmatic rocks of the Sierra Nevada Batholith, e.g., at Yosemite National Park?  
    • 24.5 miles, the Christmas Lake Dike crosses the highway at this south-facing switchback (barrow pit quarry); originally mapped and described by Prinz (1964, 1965). This dike was dated at 774 Ma by Harlan et al., (1997)
    • 30.5 miles Gardner Lake Overlook (south); another photo opportunity and Gardner Lake Trail . The Little Rock Creek Trail (#613) is part of the Beartooth Loop Trail that returns to the Beartooth Highway near Long Lake.
    • 32.5 miles. Beartooth Pass, elevation 10,947 feet.
  • 37.2 miles, Stop 6 Long Lake Magmatic Complex, Park safely off-road on the north side of highway in the open meadow.  This is a good location to look in detail at the complex magmatic relations in the 2.8 Ga Long Lake Magmatic Complex.  Rock types range in composition from intermediate (dioritic/andesitic) to granodiorites and granites with some late-stage cross-cutting granitic pegmatities.  In detail each of these rock types can cut across all of the other rock types, indicating that they have all been intruded at roughly the same time. Some of the rocks have a well-developed foliation defined by planar orientation of micas or lineation defined by preferred orientation of elongate amphiboles, indicating that these rocks were partially intruded during active deformation. Other units may exhibit structures that result from magma mixing  or partial assimilation of earlier rocks by younger intruding rocks.  There are also regions where magmas have been injected along parallel planes, called lit-par-lit (side-by-side) injections. There are some outcrops that contain a dull-brown, cm-scale, prismatic mineral with rusty alteration rims; this mineral is a Rare Earth Element variety of epidote identified as allanite. 
    • Just east of this location, the NW-trending Long Lake Dike is exposed at the surface, and can be traced for miles in Google Earth or air photo images.
  • Houser Lake/Beartooth Lake Trail #629 (trailhead south of Long Lake) intersects with the Gardner Lake Trail.
  • Morrison Jeep Trail (Forest Road #120), south of Long Lake,  gives access to Chain Lakes area, Sawtooth Mountain and Lake, and eventually connects to Canyon Road to Wyoming State Highway 120 to Cody, WY
  • 40 Miles, Island Lake Campground, (pit toilets and water available); This is a great portal to the core of the Beartooth Mountains as Island Lake is at an elevation of 9518 feet and the trails leave from here.  The Island Lake Trail connects to the Beartooth High Lakes Trail (620) and provides access to Becker (in Wyoming), Jasper and Albino Lakes  (in Montana) in the core of the range and loops back to Beartooth Lake on Beartooth Creek Trail 619  and  Beauty Lake Loop (8.5 miles point to point). Additional information from MontanaHikes.com can be found at Island Lake at the Beartooth Plateau.
  • 40.5 Miles Stop 7:  The Great Unconformity, just east of the Top of the World Resort, park near the guard rail on east side of bridge that crosses the unnamed creek. Walk ~50 meters north of bridge, cross the small creek. This is a great exposure of the Great Unconformity. At this location, the 2.8 Ga magmatic rocks of the Long Lake Magmatic Complex are in unconformable contact with the Middle Cambrian (~560 Ma) Flathead Sandstone. At this location you can literally cross 2.3 billion years of missing Earth history in a single step.
  • 43 miles, Stop 8 Beartooth Lake Campground, pit toilet, water, picnic day use areas available; View across the lake to Beartooth Butte which is one of the few erosional remnants of Paleozoic rocks on the plateau. Descriptions of camping and hiking are available from the Shoshone National Forest Beartooth Lake Campground  website and from MontanaHikes.com can be found at Beartooth Lake. Trails from Beartooth Lake connect with trails to Island Lake (Beauty Lake 621 or Beartooth Creek 619) and Clay Butte (Clay Butte Trail 614). Beartooth High Lakes and Beauty Lake Loop .
    •   Beartooth Butte is famous for its occurrences of Devonian fish and terrestrial plant fossils--some of the oldest in the world originally described by Bryant (1933) and Dorf (1933). Collecting is restricted at this site.
    • The low ridge just west of the lake is a mafic dike known as the "Leopard Rock" due to the spotted appearance from cm-scale labradorite phenocrysts (described by Martin Prinz) with an age reported at 2200 Ma (Harlan, 2003).
    • Just west of Beartooth Lake, and starting the descent down the valley, Beartooth Falls is on the south side of the road.
  • 45 Miles, Clay Butte Lookout , provides great scenic overviews of the area, access to Paloeozoic sedimentary rocks around Beartooth Butte, and the Clay Butte Trailhead
  • 45.4 miles, Stop 9: Index and Pilot (Absaroka) Vista:  This site gives a great panoramic view of Pilot and Index peaks, the Clark Fork of the Yellowstone valley, and high plateaus of the Beartooth block north of Cooke City, Montana
    • The bedrock geology of the skyline to the west and south is the rugged Eocene Absaroka Volcanic Group. For an overview, see the USGS Yellowstone Volcano Observatory report: The Other Volcanic Range in the Yellowstone Region: The Absarokas.
    • The white cliffs across the Clark Fork of the Yellowstone are the Ordovician Bighorn Dolomite. This is the footwall of the famous Heart Mountain Detachment gravity slide.
  • 48 miles, Sunlight Basin, Chief Joseph Scenic Highway (Crandall Road, 296 to Cody, WY); This road will take you to key locations to explore the Heart Mountain Detachment in more detail a) 11 miles south provides a panoramic view of the Cathedral Cliffs location; b) continuing south cross Sunlight Creek to access the White Mountain location on Rd 101 west, cross Sunlight Creek and head back east on Rd 104. Details are in this Heart Mountain Road Log (Acrobat (PDF) 5.9MB Dec12 24).
  • 65 Miles, Highway 212 to Cooke City. The road is mostly in forested cover in this stretch, but the bedrock geology is the Eocene Absaroka Volcanics.
  • The Russell Creek Trail (#3), trailhead at Clark's Fork Picnic Area, connects to the East Rosebud Trail (#15) at Fossil Lake to complete "The Beaten Path".  Side trails are Broadwater River Trail, Vernon Lake Trail, Rock Island Lake Trail, Widewater Trail. and Fox Lake Trail. These trails traverse relatively low topography of glacial polished granite outcrops of the 2.8 Ga LLMC suite.
  • Debris flow scars and deposits are evident in many of the streams that flow off the high peaks in this area.
  • Cooke City Mining District is north of the highway in the Crown Butte, Daisy Pass areas.  Access this historic mining district via the Lulu Pass Trail Rd that loops around and connects to the Daisy Pass Trail Road back to Cooke City.  The upper stretches of these roads can be quite rugged, and street vehicles are not recommended.  Mine development areas are located proximal to Henderson Mountain and Scotch Bonnet Mountain. 

    • Another primitive road branches off to the NW to Lake Abundance and trail head (#398). The Stillwater River Trail (#24) terminates at the Lake Abundance Trail head and after 26 miles connects with the northern trail head at Woodbine Campground near the Stillwater Complex.