Jasper Mountain is a beautiful peak in the Indian Peaks Wilderness west of Boulder, Colorado, which has no less than five ridges leading up to its summit. It's south east ridge stretches for two miles from Pt. 12,055 to the summit and is composed almost entirely of firm, high quality rock or flower speckled tundra (at least in summer). It makes for a highly recommended route either for an ascent of the peak, or an interesting means to descend after completing on of the other lines!
One note for the record is that I actually traversed this ridge as a descent from Peak 12,660, starting near the summit of Jasper and ending up at Point 12,055. I would strongly recommend this as an engaging means of returning from an ascent of that peak.
Jasper Peak from its South East Ridge.
The Fourth of July Trailhead is the closest one to this route. From the trailhead, ascend the Arapahoe Pass trail for about a mile, then turn left onto the Diamond Trail which crosses the North Fork of Middle Boulder Creek then ascends several hundred feet to Diamond Lake. From here, take the faint trail around the shoulder to the east. Once onto the eastern flanks of Pt. 12,055, one can ascend through thin forest cover, then largely tundra and snowslopes towards Pt. 12,055.
An alternate approach is via the Devil's Thumb Bypass trail from the Hessie Trailhead. Once on the Devil's Thumb trail continue until about 0.6 miles from Jasper Lake, where one can work their way to Pt. 12,055.
If one uses this route as a descent from Pk. 12,660, walk north and west from its summit towards Jasper Peak. Shortly after reaching the low point on the southern ridge of Jasper, traverse east, possibly on snow, to the ridge. If this approach is used, you will actually traverse the ridge in reverse. Once at Pt. 12,055 continue east then either turn north to reach the Fourth of July Trailhead, or South to get back to the Devils Thumb Trail. There are several large cairns marking where the Diamond Lake Trail crosses the broad eastern ridge of Pt. 12,055. One final note is that when I was descending this line, I started going down the Diamond Lake Trail, then grew weary of following the faint trail through many snowdrifts and bailed straight down the slope to the Fourth of July Trailhead. There were bridges across the North Fork of Middle Boulder Creek in the vicinity of the trailhead.
The route is shown in Red, with alternate starts either from the Diamond Lake Trail or the Devil's Thumb Trail. Possible descent lines back to each trail are shown in purple, with the Devil's Thumb descent briefly leaving the left side of the picture.
From Pt. 12,055, walk west on beautiful tundra for several hundred yards to a 12,040 foot ridge point. From here, continue west on the ridge which soon gets narrow. There are two distinct notches in the ridge between here and Pt. 12,294. To reach the first one, descend a narrow tundra filled gully that angles south off of the ridge when it starts to get cliffy. from the notch, one can traverse slightly to the north to regain the ridge. The second notch is technically not difficult but holds about the only portion of the line where the rock is not outstanding. From here it is about a mile along wonderful firm rock to the summit of Jasper. Except for the one notch noted above, the best line is found walking directly on the ridge top. Most of the traverse is second class with a few spots of third class mixed in.
The ridge as seen just before the first notch. From here, descend a tundra filled gully, then walk beneath cliffs to the notch. From there traverse slightly north to regain the ridge crest.
Looking back from near the summit of Pt. 12,294 to Pt. 12,055. This is the most technical portion of the ridge.
The South East Ridge of Jasper. The crest of the ridge is firm rock as shown in a number of sections.
From the top of Jasper, it is frequently possible to descend by a quick glissade into the valley with Diamond Lake and then walk down this to rejoin the Diamond Lake Trail and from there return to the Fourth of July Trailhead. If the line shown on the map is melted or too steep, an easier one would be to cross over the subpeak on the East Ridge, then descend east along this line to the south facing snowfield where a great glissade can be made to the valley bottom. One can also follow the broad ridge south from Jasper's summit over Pk. 12,660 eventually reaching the Devils Thumb Trail which can be followed back to the Hessie Trailhead.
Standard hiking gear is all that is required. This is not a technical route. During most of the year, it would be wise to carry an ice axe for any glissades on the descent.