Southeast Slope

Page Type Page Type: Route
Location Lat/Lon: 37.07156°N / 118.445°W
Additional Information Route Type: Hiking, Mountaineering
Seasons Season: Spring, Summer, Fall, Winter
Additional Information Time Required: One to two days
Additional Information Difficulty: Class 2
Sign the Climber's Log


The southeast slopes of The Thumb offer the easiest route to the summit of this seldom climbed member of the famed Palisades group. The route follows a trail to Birch Lake then heads west and northwest over class 2 terrain to the summit. The Thumb also makes a nice winter hike with snowshoes, crampons, and ice axe required.

Note on Approach

approachPassing the gate you can drive through this section.

The trailhead is somewhat tricky to find and the roads leading to it are poorly marked, the directions posted on the Birch Mountain page are accurate. They suggest, however, that you stop at the barbed-wire gate where the road gets quite rocky. For some there is no option but to stop here, but if you have the vehicle for it you may wish to try and continue farther. The rough rocky section after the gate is very short, and once passed, the road is in good condition for maybe another mile or so. Take a left (west) at the first branch, then park off the road at the right-hand branch. Walk from here, what starts as a faint road dwindles to a trail shortly. If you are able to drive past the gate you will save yourself maybe a mile of frustrating flat walking.

Route Description

The ThumbLooking up Birch Creek to The Thumb

A trail runs to Birch Lake. We hiked this route in the winter but were basically able to follow the route of the trail most of the way through variable snow cover. The parts of the trail we saw were in good condition, though I cannot vouch for the entire length. The trail starts up a small valley immediately north of Birch Creek then runs along the south wall of Birch Creek canyon finally contouring around to reach Birch Lake. The trail route marked on topozone seems accurate.

The Thumb - First LightThe Thumb from Birch Lake

The elevation gain from Birch Lake to The Thumb is approximately 2600 feet. Birch Lake is enclosed by steep moraine and rock walls to the west so pick your poison and ascend to the moraine crest. We ascended the southern portion of this slope adjacent to Birch Mountain and ended up descending the northern side of this small basin back to the lake. The northern side was a bit steeper but more direct. We did this hike in winter so this section was totally snow covered; a use trail may exist.

The Thumb - south rampThe gulley at far left access The Thumb's southeast slope.

After reaching the moraine crest, head west for the steep gulley that accesses The Thumb’s southeast slope. The gulley is short but steep, maybe 35-40 degrees, (class 2 in summer) and faces southeast. In winter be aware of avalanche danger in this section. Once the gentle southeast slope is gained the rest of the route is straight forward. Head for the obvious summit of The Thumb over class 2 terrain, the slope angle increases gradually as you ascend. The summit blocks are large but never harder than class 2.

In summer, this hike could be done as a long day or as an overnighter. There are a few good camp spots at Birch Lake. In winter the same applies, some have skied up and back in a day, while most will probably choose to camp at Birch Lake. Ski ascents seemed common reading through the summit register. Views to north of the Middle Palisade, Norman Clyde Peak, North Palisade and Mount Sill are outstanding!
Middle Palisade BasinSummit view looking north from The Thumb over the Middle Palisade Basin.

Essential Gear

In summer, bring your standard hiking gear. In winter, snowshoes, crampons, and ice axe are required. Avalanche gear (beacon, shovel, probe) is highly recommended in winter and spring.

External Links

A good ski trip report:



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.

The ThumbRoutes