The route description for UN 13,054 (Pyramid Mountain) begins at the trail intersection east and above Rito Alto Lake where trails #747 and 745 meet. Mileage and elevation gain are measured from that point. If beginning this hike from Rito Alto Lake, add an additional .7 mile one way and 340 feet of elevation gain.
From the trail intersection mentioned in the approach, head SE following trail to a pass at 12,220 ft. This is a well-used trail by pack-horses and is steep and rugged toward the crest of the pass. On the other side, it drops steeply as well, especially as it heads into a section in the trees. The trail then crosses San Isabel creek through willows. It could be easy to lose here, but if you watch carefully, a couple of specifically placed cairns mark the trail on the other side of the creek and point the way up to San Isabel Lake. If you will make sure you identify the trail after crossing the creek, there will be no real difficulty following it except for one brief section. It will lead all the way to the lake where it ends at some potentially nice campsites.
This beautiful little San Isabel Lake is situated in a basin, wrapped around by high ridges with steep walls of rock and some tundra. When we arrived here at 8:40 AM, the lake was calm and offered a beautiful reflection. On the south end of the lake, there is a lush and tall growth of a deep green plants that are topped by pure, white flower clusters. From the lake, there are at least four options for climbing the peak which actually lay over a mile distant behind the encircling ridges of this basin. Two of the options would have you swing east up the basin and gain the upper portions below the actual ridgeline and then contour back west to gain the main ridge that leads south to the summit. Another option is to ascend SSW from the lake to a saddle at 12,380 ft. A fourth option is to contour west around the prominent ridge buttress, then turn south and gain the top of the buttress and intersect the aforementioned saddle. We chose the third option, which had the advantage of being the most direct and which did not seem all that bad, even though we knew it would be steep.
Walk up along the east side of the lake and continue south, heading into the lush flowering plants and trying to follow alongside shallow little rivulets, but staying out of the water. Avoiding the running water for us was of little help though because the plants were soaked from previous rains and morning dew. They quickly drenched our boots. As we headed up through all the plants, we began to turn SW and after about 400 feet of gain, came to the real problem of the day. Escaping the tall plants, we found ourselves on tundra slopes with grass, interspersed with rocks and boulders. We began hiking up much steeper terrain heading for the saddle more than another 400 feet up. At first, it was not too difficult to find tundra benches that wove a path in between rocky outcrops. But the higher we went, the steeper it became, and the more narrow the benches. At times, it was almost like rock climbing on tundra. There were places where even though our footing was fairly secure on the tundra, you felt a sense of exposure and continued upward progress seemed to require 3rd class scrambling. The easier sections below had lured us onto more difficult paths. We tried leaving a few cairns behind in case we came back this way, but we found this ascent route so intimidating, it was not difficult, later in the day to choose another route down.
Farther up, the slope angle finally lessens some and we found ourselves scrambling on more small rock and less tundra. Finally, we arrived at the saddle where we saw evidence of elk, but actually spotted none. From this saddle, the remainder of the route is much easier, but not fast as you walk over mostly tundra slopes with the embedded rocks so frequent to this entire range. There were at times, rock outcrops to deal with and talus areas of moderate boulders. The remainder of the route first leads upward to the SE to gain the highest point of the ridge surrounding the lake. Once on the upper ridge, turn south to follow it over the 12,957 marked summit and continue south to UN 13,054, passing another false summit along the way. Most of the ridge is low tundra with embedded rocks.
UN 13,054 "Pyramid Mountain," is the high point of a subset group of peaks on the west side of the main spine of the Sangre de Cristo range. The “Groundhog Basin” below on the east side looks remote and inviting. You can gaze partially down into it through a rugged cleft on the NE face of this peak. From our perspective, you could look either south or north along the range and see the highly tilted, conglomerate, layered rocks in clear relief that so characterize this entire area. If there is any threat of weather, it is best however to not linger too long on this wonderfully isolated summit because the trek back leaves you on exposed ridge for quite a distance.
For the descent, return to the saddle above the lake at 12,380 ft. (As we looked down upon the saddle, we watched a small group of elk cross up to the saddle from the east side, then when they spotted us, they moved off to the north end of the ridge and disappeared from site.) Since elk do not climb cliffs, their descent to the north aroused our interest, so we hiked to the top of the 12,445 marker instead of returning back down the steep slope we had come up from the lake on. From the 12,445 point we headed down the north slope. A photo we had from a friend of this north slope indicated a tundra covered slope that swept down the north side several hundred feet and then a more horizontal tundra bench that would lead us back over to the lake with some willows as you approach the lake. We followed this route as best we could. From the 12,445 point, we headed down following the natural slope of the strata for a while before cutting back east on a minor tundra bench and then hitting the wider tundra slope in the photo. There was a fairly deep gully that guided us down for some distance, but there’s any number of ways you could make your way down this mountainside. You just have to be careful to avoid the rockier outcrops and sloping cliffs. As the contours tightened up, we decided that we needed to begin contouring back to the east, hoping to come out in the vicinity of the lake. We had to cross some more minor gullies and traverse both rock and tundra, but to our relief, we did come out a little above the lake and worked our way down to the NW corner of the lake where the terrain dropped us into a swag a little below the lake. We hiked up out of that and got back to the lake level, where we located the trail back down to San Isabel Creek. Follow the trail back up over the 12,220 foot pass, then back down to the trail intersection or Rito Alto Lake.
Links to other information, routes & trip reports for this peak that may be helpful.