El Capitan Granite

El Capitan Granite is a type of granite (also see granodiorite), in a large area near El Capitan, in Yosemite National Park, California, United States. The granite forms part of the Tuolumne Intrusive Suite (also known as Tuolumne Batholith), one of the four major intrusive suites within the Sierra Nevada.

A geologic map of Yosemite National Park

El Capitan granite is mostly unjointed.[1]

Composition

The granite has abundant quartz, plagioclase, crystals of orthoclase, and both feldspars — orthoclase and plagioclase — are white. Hornblende is rare, compared to other Yosemite granites. Most black minerals are biotite.[2]

Granite of Yosemite Valley

Location

It is found west of Half Dome Granodiorite, both north and south, to a western limit near Cookie Cliffs.

All of Turtleback Dome, El Capitan, The Three Brothers, and Cathedral Rocks are made of El Capitan Granite[3] as is Elephant Rock.[4]

El Capitan Granite makes up most of the granite found in the west half of the Yosemite Valley area.[5]

Age

El Capitan Granite intruded older plutonic rocks about 103 Ma,[3] during the Cretaceous Period.

El Capitan

See also

References
  1. N. King Huber and Julie A. Roller from the writings of Frank C. Calkins and other sources (1985). "Relation of Landforms to Rock Composition and Structure". Retrieved 12 May 2016.
  2. Glazner, Allen F, Stock, Greg M. (2010). Geology Underfoot in Yosemite. Mountain Press, p. 45. ISBN 978-0-87842-568-6
  3. N. King Huber and Julie A. Roller from the writings of Frank C. Calkins and other sources (1985). "Rocks of the Yosemite Valley Area". Retrieved 12 May 2016.
  4. s (1 June 1985). "Roadside Geology of Yosemite Valleya". Retrieved 12 May 2016.
  5. N. King Huber (1985). "Yosemite Valley area". Retrieved 12 May 2016.


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