California

Mt. Whitney
       7 ½’ quadrangle: Mt. Whitney, CA
       Inyo and Tulare Counties
       On the divide between Sequoia National Park and Inyo National Forest
       John Muir Wilderness. Hiking permit required, by lottery.        Sierra Nevada Range.

Intrusive Igneous
14,494 ft (4,418 m)
Bedrock: Mount Whitney granodiorite Cretaceous (83 Ma)

Light gray hornblende-biotite-plagioclase-quartz granodiorite. The Mount Whitney pluton, the youngest member of the Mount Whitney Intrusive Suite, is zoned from granodiorite near the margins to granite at the center. It is part of the huge Sierra Nevada batholith, which includes ten other peaks over 14,000 feet. Their great height is due largely to about 11,000 feet of uplift and tilting of the Sierra Nevada block relative to the Owens Valley to the east along the Sierra Nevada normal fault, active during the Miocene and Pleistocene epochs. A major earthquake in 1872 at Lone Pine, directly east of Mt. Whitney, suggests that faulting along the eastern Sierra has not ceased.

Placer gold found in streams along the western foothills of the Sierra Nevada was at first assumed to have washed down from "mother lodes" in the mountains, and the California Geological Survey was in part established to search for gold deposits in bedrock. Eventually it was realized that the sources lay farther east in Nevada, and that gold had been carried by streams flowing westward before the rise of the Sierra Nevada range. Mt. Whitney was named for the first state geologist, Josiah Dwight Whitney.

Surficial Geology: The mountain is embayed by valley glacier cirques with associated arêtes and tarns, especially on the east side, and scarred by avalanche chutes. However, Whitney’s dramatic serrated summit profile is the result of erosion along a system of steep joints. The trail from the east side ascends a steep talus slope through numerous switchbacks. The west slope is more gradual than the sheer 2000-foot drop east of the summit.

Soil Series: No soil survey has been published for this area. Bare rock and loose blocks are at the summit, along with a stone hut built by the Smithsonian Institution for a weather station.

Selected References:

  • Hirt, William H. and G. Hines, 2002, Anatomy of a fossil magma chamber: zoning and closed system fractionation in the Whitney pluton, Sierra Nevada, California: Geological Society of America Abstracts v.34, no.5, p.79.
  • Norris, Robert M. and R.W. Webb, 1990, Geology of California, 2d Ed.: John Wiley & Sons

Other suggested sources of information:


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