Mount Sentinel in the Bob Marshall

Ralph Thornton works way up Mount Sentinel in Bob Marshall Wilderness

On top Sentinel

I’m very taken with the Bob Marshall Wilderness Area just west of Swift Reservoir outside Dupuyer and returned for my third trip this season, this time to climb Mount Sentinel, elevation 7,680.
There couldn’t have been a more spectacular fall day to do this trip. The cottonwoods and aspens were in glorious golden, brown and orange. Lots of the groundcover and shrubs covering the mountainsides were brilliant red. There was no wind and the sky was a bright blue.
I like this area because it delivers a quick wilderness experience, it is an extension of the Rocky Mountain Front, and the named mountains are easily accessible.
I had been looking at Sentinel for a number of years and have contemplated a traverse from adjacent Mount Richmond along a knifey ridgeline.
Monday’s trip was intended to spy that ridgeline and see if it is remotely doable.
My conclusion is that it is doable, but one would need ideal conditions and one of the longest days of summer to get the job done.
I had climbed Mount Richmond a year ago and had that perspective to inform me for this trip.
Earlier this summer several partners on the Mount Field trip had started up Mount Sentinel on the Tubby Creek ridge, and one of them, Byron Wallis, made it, racing most of the way so we didn’t have to wait on him.
My partner on this trip was Ralph Thornton of Choteau, the capable Glacier Mountaineering Society climber who has begun moving some of his climbing south from the park in the spring and fall.
We began our climb on the first ridge, west, just beyond the junction of the Middle and South Forks of Birch Creek, immediately encountering limestone scree for nearly 800 feet before accessing the ridgeline above towering limestone faces.
The climb reminded me a lot of Mount Crandell in Waterton Park. Crandell is the large, limestone mountain above the town site of which the Bear’s Hump is a part.
Just like Crandell, Sentinel has dominant limestone ridges, but also offers adjacent easier, treed slopes as an alternative.
Negotiating the limestone layers of Sentinel required some use of hands on easy third class pitches. Occasionally, the ridgeline got a little narrow and hairy to walk, in which case it was easy to descend below it for a less exciting experience.
There are three peaks at the top, the first 104 feet lower than the summit. If you take this route you have to drop down from the end of this peak about 30 feet through an exposed Class 4 pitch that would have been more comfortable with rope.
The views from the top of Sentinel are exceptional. It is a well-named peak because it sits in the middle of the valley with high peaks all around. We could see Silvertip and Pentagon deep within the Bob. There were peaks of the Front including Ear, Rocky, Teton and Baldy. The Badger Two Medicine and Glacier Park were to the north and the Great Plains and Swift Reservoir to the east. The forks of Birch Creek were silver threads winding their way through the valley.
We dropped off the lowest peak and traversed along a timbered ridge to the east with its three cliff bands.
About the only downside of the climb, if you can call it that, was the long walk out around Swift Reservoir.
It makes for a lengthy, if eventful day.