Red Dome’s crimson hills a cool trek southeast of Bridger

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Red Dome

Red rock formations southeast of Bridger are part of the Chugwater Formation, where iron minerals in the soil have oxidized turning the soil and sandstone red.

Hiking among the crimson cliffs of Red Dome, located about 10 miles southeast of Bridger, seems like a trip back in time.

The red bluffs on the north and east sides of Pryor Mountain Road are checker-boarded with state and BLM lands. The hunting season provides a great time to explore the country because the private lands are included in Montana Fish, Wildlife and Parks’ Block Management Program. The program pays landowners to provide access to their private property.

Rock block

A large, isolated block of sandstone weathers the wind, rain and snow on BLM land southeast of Bridger.

In FWP’s Region 5, the Block Management Area is No. 115, the JS Morgan Ranch. No motorized vehicles are allowed on the private land, so it’s walk-in only for mule deer. Upland birds are also listed as a possible species in the area.

A photo-illustrated roadside geology tour posted online by the Pryors Coalition that includes Red Dome along the route to the Pryor Mountains. According to geologist Gary Thompson the road cuts through 400 million years of geologic history. That includes Red Dome, which is part of the Triassic period Chugwater Formation, dating back 251 million years ago to when North America was still part of the huge super continent known as Pangaea.

The red sandstone comes from oxidation of iron minerals in the soil.

Livingston trail provides mountain views along Yellowstone River

“One source of the iron oxide is from deeply weathered tropical soils that existed at that time,” Thompson wrote. “There are some gray streaks in these reddish rocks that are impregnated with deposits of tar. The tar is a residue of crude oil that was once trapped under an impermeable layer of gypsum in the dome.”

Portions of the Chugwater Formation can be found farther south along the Pryor Mountains near Crooked Creek, as well.

“The Chugwater Formation comprises about 500 feet of red shale, siltstone, and sandstone likely deposited in ephemeral lakes and small streams during the Early Triassic,” Thompson wrote.

If it is not hunting season, please explore this area only if you have an app or GPS that shows private land ownership to avoid trespassing. The Montana Cadastral website can also provide information on where to access the area, showing where BLM land meets the Pryor Mountain Road.

The easiest access is atop a hill about 11 miles from Bridger where there is a half section of BLM land that meets the road. Taking this route north up a valley connects to a full section of state land. This section of state land includes part of Bridger Creek and also adjoins additional portions of BLM land.

State land is accessible only to those who purchase a State Land Recreation Use Permit, which can be purchased through FWP online. The permits are $10 for adults, $5 for those age 17 and younger and seniors 60 and older. A family permit is available for $20.

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