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.
El Capitan granite is mostly unjointed.
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.
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 as is Elephant Rock.
El Capitan Granite makes up most of the granite found in the west half of the Yosemite Valley area.
Age
El Capitan Granite intruded older plutonic rocks about 103 Ma, during the Cretaceous Period.