Follow the approach for the Standard West Ridge route. You can leave the trail anytime past Lake Winnemucca.
The Crescent Moon Couloir is the prominent chute in the center of Round Top's North Face, providing nearly 500ft of exciting snow/ice climbing. In winter it is filled with avalanche-prone snow, consolidating to hard snow/ice into late spring and summer. You can approach the base of the couloir by a variety of routes on the broad lower reaches of the North Face. Either choose a direct line from Lake Winnemucca, or any variation leaving the trail west of the lake.
On the right side of the couloir a small flat platform may be found below just below a huge rock face. This provides a convenient place to switch from skis or snowshoes to crampons. The bottom of the couloir starts at 40 degrees, growing steeper as one climbs higher. One third of the way up, the couloir splits in two. The steeper left fork heads more directly to the higher east summit. The right fork (for which the Crescent Moon name derives) curves to the right before ending just right of the lower west summit. Once past the curve in the right fork, the slope exceeds 50 degrees and may be difficult to exit in soft snow conditions. Neither fork appears to form a cornice at the top, providing a straightforward exit in most conditions.
Though the overall angle of the left fork is steeper, it does not have the extreme steepness at the exit as does the right fork. It also leads more directly to the higher east summit, ending at notch between the two summits. This route seems to be used less used than the right fork, though no less enjoyable.
In general, the snow does not reach hard conditions until late in spring due to its protection from the sun. Conditions can vary within the couloir considerably. The snow in the middle section tends to be the hardest. This can be a real hazard for those considering a descent only. The snow may be soft for kicking steps for the first 50 yards down or so, then get progressively harder. This can be extremely trying on your legs and toes. Consider aborting a descent and retracing your route back up and then down the West Ridge if you get in trouble. Falling is not an option.
The attraction of this route is primarily as a winter ascent/descent. Misha offers this comment for those considering a summer/fall climb: Do not climb up or down this couloir during late summer / early fall months unless you enjoy miserable scree and occasional ice patches on a steep terrain. Rock-fall danger is extremely high, as many parties that pass above the couloir on the summit ridge drop rocks into it. One word to describe its no-snow conditions: NASTY!
Crampons and axe for most conditions. Avalanche transponders are recommended if you are unsure of snow conditions in the chute. As a minimum, you should wait for the snow in the broad lower reaches of the North Face to consolidate before climbing. rhyang adds: In case you decide to rope up, the rock on the couloir walls seems crumbly and crappy. Probably better to use pickets for pro.
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