Page Type Page Type: Mountain/Rock
Location Lat/Lon: 44.48491°N / 112.55°W
Additional Information County: Clark,Beaverhead
Activities Activities: Hiking, Bouldering, Scrambling
Seasons Season: Summer, Fall
Additional Information Elevation: 9880 ft / 3011 m
Sign the Climber's Log


From their eastern reaches starting at Monida Pass, the Beaverhead Mountains begin their journey upward along the Continental Divide. As they rise westward, the first real mountain that you encounter on the divide is a 9000' peak with two summits.

The highest summit is The Knuckle which anchors the eastern end and contours out at 9880'. The western summit reaches to 9787' and is anchored on the far western end by The Thumb at 9760'. The Thumb carries the only official name and with good reason as this rocky protusion is the dominant feature.

Images of The Thumb are rare. The best may be a photo taken by 'Hiking Idaho' author Ralph Maughan which can be googled easily enough by searching 'The Thumb Beaverhead Mountains'. He also has it posted on Google Earth.
The ThumbThe Thumb

You can drive quite close to The Thumb from the Idaho side as there are scattered ranches along the well maintained Medicine Lodge Road. CDT thru hikers can see this unique formation from Montana as they make their way along the CDT. You can also pick out The Thumb from I-15 in southwest Montana if you know what to look for.

These Beaverhead peaks aren't the highest or most sought after, but taking a shot at The Thumb might be a prize worth attaining.

Getting There


Access is via Medicine Lodge Road which is located about 5 miles west of Dubois, Idaho on Hwy 22. Travel 26 miles to Irving Creek Road which is signed. Fortunately, the first 21 miles of Medicine Lodge Road is paved and it is excellent gravel for the next 5 miles.

Turn right onto Irving Creek Road and travel 12 miles. Along this 12 mile stretch you will pass by the Angielen Ranch. A couple different road options face you here. Take the one that is straight ahead. Your topo map will show this as The Bull Pen. After 12 miles, there is a sign that says 193. From this point it is about 1/2 mile to the base of the mountain and you can certainly drive the single track that far if you want.

The last couple of miles a high clearance rig is advised. You might need 4WD to plow through a couple of mud holes or to get turned around.


An approach can be made from I-15. Unfortunately, negotiating the private ranches and roads is territory I am unfamiliar with.

Summit Routes

Option 1
The ThumbThe Thumb

Work your way up from the base of the western summit. If you gain the ridge first and then head for The Thumb, there is some Class 3 terrain and a couple of Class 4 down climbs to negotiate. All can be avoided by dropping to the south of the ridge as needed as you work toward the base of The Thumb.

Otherwise, once you gain the ridge, follow it east and pick your best line to the summit of The Knuckle.

Option 2
The KnuckleThe Knuckle

Work your way east aiming for the open slopes above you. Once attained, these slopes offer an easy Class 2 ascent to the summit of The Knuckle. From the summit, drop to the 9600' saddle and pick your best line as you traverse west to The Thumb.

Climbing The Thumb

Although I am not a rock climber, here are some options and you can go from there. I was able to navigate 75% of The Thumb without any difficulty and pick out three possible lines.

EAST SIDE - Class 5
East sideEast side closeup
The Thumb s east sideEast side route

Hand and foot holds looked solid but on the small side. The first impression here was that if you slip up high, it is bounce once, bounce twice, hit the deck. No attempt made.

SOUTH SIDE - Class 4/5
South side diagonalSouth side diagonal

This diagonal cut had a couple of zigs and zags to it and I could not see the upper portions of the route. No attempt made.

Northwest routeNorthwest route

This may be your best choice. The start involves a Class 3 climb through a narrow opening under a tightly lodged rock. No wide bodies allowed. Above the narrow opening a dog leg left leads to a flat staging area where the real climbing begins. At this point you are about 30 feet shy of the summit.

An overhanging rounded rock is the first obstacle that must be solved. The holds are solid but small. Gravity is the biggest problem as it wants to pull you back and off the rock. A short diagonal runs above the rock which leads to a vertical chute. The top of the chute curved and I could not see beyond that. If you can solve the rock, negotiate the diagonal, and climb the chute, you will most likely find yourself on top.

Unable to solve the rock, this is as far as I got. Sorry that there is no picture as the camera and backpack did not make it through the narrow opening. I can pick out the rock and route from Ralph Maughan's photo, although from long distance his photo may not be much help.


Smooth Face PeakSmooth Face Peak

This Idaho peak with its smooth open slopes and Mohawk styled summit ridge, rises about 1.5 miles to the west of The Thumb. If pursuing Smooth Face, dropping directly off The Thumb to the west may not be the best choice for a descent. Otherwise, it is climbers choice on Smooth Face Peak's slopes.


If camping overnight up Irving Creek Road this makes for an easy evening hike. Located roughly 3 miles to the south of The Thumb, these grassy slopes and open summit are the ticket for occupying some down time. Any route is a go here.

Post Hike Amenities

For those of us who are soft city folk and like our modern creature comforts, there is a convenience store in Dubois that has everything. They have first rate shower facilities, a deli that serves hot meals, and a well stocked grocery section.

It is located in the NE corner where Hwy 22 and I-15 intersect. Bad on me for not remembering the name of this place.


There are several informal camping spots along Medicine Lodge Creek, although you may have to do battle with the trailer camper crowd.

Futher up Irving Creek Road, as you get beyond the Angielen Ranch you will find wide open country conducive to camping.



Parents refers to a larger category under which an object falls. For example, theAconcagua mountain page has the 'Aconcagua Group' and the 'Seven Summits' asparents and is a parent itself to many routes, photos, and Trip Reports.

Beaverhead MountainsMountains & Rocks