Telegraph Peak, is a peak of the San Gabriel Mountains, in the San Gabriel Mountains National Monument and San Bernardino County, California.
With an elevation of , it is highest point in the Cucamonga Wilderness of the San Bernardino National Forest.
Most of the bedrock, including that of the summit, is cataclastic gneiss. Granodiorite underlies much of the southern portion.https://ngmdb.usgs.gov/Prodesc/proddesc_71733.htm Dibblee, T.W., and Minch, J.A., 2003. Geologic map of the Telegraph Peak and Phelan quadrangles, San Bernardino County, California
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