Mammoth Rock is a notable landmark of the Mammoth Lakes area, overlooking the town of Mammoth Lakes on its southwestern end. Though overshadowed by nearby Mammoth Mountain, visitors to the area find Mammoth Rock has a more aesthetic look, and homes in the area use views of this landmark as an important selling point.
In an area that is dominated by volcanic rock, Mammoth Rock is a limestone and marble formation, giving it a bleached-white look amid a background of brown, purple, and other darker colored rocks. Sitting on the side of a volcanic ridge that lies between the town and Lake Mary, Mammoth Rock has weathered errosion forces better than the surrounding volcanic rock, and over the eons it has emerged as a plug that dominates the upper part of Snowcreek Meadow.
Because of its unusual rock compostion, it attracted the attention of miners over a hundred years ago. Nearby Mill City is the historical site of the first white inhabitants in the area. Remnants of the old mining town still abound, though mostly as lumber lying haphazardly about the forest floor. An abandoned portable stamp mill can be found a short ways from the trailhead, lying on the bed of a rusting trailer. At the base of Mammoth Rock on the northwest side is an abandoned mine, some 100ft deep that bores into the base of the rock formation. It doesn't look like the owners ever got anything valuable out of it, but interesting crystals can be found embedded in the ceiling.
Most sides of Mammoth Rock are steep and difficult to ascend, but the southwest side facing the higher ridge behind it offers several class 3 routes to the summit. Mammoth Rock is less than a mile from the trailhead and can easily be climbed in an hour by the easy routes. More technical routes on three other sides are possible, from two to three pitches each, but I have found no information concerning these. I'll keep looking. If you know of any, please add a note here!
From town, head south on Old Mammoth Road and follow it for about three miles to about a half mile south of the junction with Lake Mary Road. If coming from the vicinity of Mammoth Mountain, take the Lake Mary Road south past Twin Lakes, turn left onto Old Mammoth Road and drive downhill about half a mile.
There are two trailheads one can use, both close together. The lower one, at a major turn in the road, has a sign indicating the Mammoth Rock Trail. The sign is off the road and non-obvious, hidden from view along the road. This trail traverses several hundred feet below Mammoth Rock as it heads down towards town. When below almost below Mammoth Rock, climb loose talus around the north and west sides to the saddle on the southwest side. On the northwest side, near the base of Mammoth Rock is the mine shaft running horizontally into the formation. There is a pile of tailings at the entrance that can be used to help locate it.
The second trailhead is shorter and quicker but less scenic. It starts at the 4WD road just up the road from the first trailhead. Follow the 4WD road up to it's end. The abandoned stamp mill is found along this route. At the very end of the 4WD trail (about a quarter mile off the road) take one of several use trails that take you up to the saddle on the southwest side. This route bypasses the mine shaft, but it can be visited as an easy side trip.
From the saddle, the easiest route to the summit follows the deep groove/chimney cut into the right side of the face here. Downclimb the other side of the saddle a short ways and climb the chimney. A class 3 route with exposure but good holds goes up on the left side of the face. See the picture for the location. I found this the more enjoyable of the two routes.
No red tape. No fees, no permits required. Camping in the surrounding area isn't permitted, but it's doubtful anyone will come after you if you are discrete. The climb of Mammoth Rock is very short, so you won't need to bother camping unless in the area for other objectives.
When To Climb
Climbing can be done any time of year, but usually in April-Oct when the area is mostly free of snow.
Camping is only allowed in designated campgrounds in the areas immediately around the town of Mammoth Lakes and up the road around Mammoth Lakes. There are campgrounds available near town, just west of the ranger station (Shady Rest and Old Shady Rest campgrounds), as well as campgrounds at Lake Mary, Twin Lakes, Lake George, and Lake Mamie. The Campgrounds at Lake George are permanently closed due to dangerous CO2 levels seeping naturally from the underlying rock (a visit to see the dead trees and warning signs at the lake are worth a side visit alone!). All of these are fee campgrounds of course. For those interested in cheaper (free) camp locations, try in the vicinity of the trailhead to Mammoth Rock, far enough from the road to avoid detection. Set up camp at dark and leave at first light.
Mammoth Lakes Visitor Center & Ranger Station can provide the latest information on trail and climbing conditions. When driving into the town of Mammoth Lakes, the ranger station is located on the north (right) side of SR203 about half a mile before the intersection with Old Mammoth Road.
See also the Eastern Sierra - Logisitcal Center