ApproachFrom the trailhead at Mosquito Flats, take the Mono Pass Trail to Ruby Lake. On the East side of the lake, unmaintained trail follows the drainage past Mills Lake to the glacier below Mt.Abbot and Mt.Mills. The Petit Griffon Spire, is the obvious "Gunsight" tower at the col between these two peaks. Climb the 35-40 degree clouloir to the base of the tower. In later season (from early August on)this might not only require ice axe, but crampons as well. There are really two towers at the col, one hidden behind the other. This route climbs the higher, western summit. The route was first climbed in 1964 by Dave McDonald and David Harvey and was the only documented ascent of the western summit as of 1996, when Miguel Carmona and I climbed it and found the register stashed in an old metal film canister. If you have an extra day in the Rock Creek area, this clean, steep spire is an excellent climb to do. See some great photos of Petit Griffon on Mt.Abbot's photo page, it's as steep as it looks.
Note: This route can also be climbed from Dade Lake, which normally serves as a camp for Bear Creek Spire and Mt.Dade climbs. Skirting the North side of Mt.Dade will soon bring you to the basin in front of the North side of Abbot/Mills.