Geologic Map of Yosemite Valley |

This map was scanned from the Geologic Map of Yosemite
National Park and Vicinity, California, U.S. Geological Survey
Miscellaneous Investigations Series Map I-1874 by N. King Huber,
Paul C. Bateman, and Clyde Wahrhaftig, published in 1989. The entire
map is available from the U.S. Geological Survey:
http://pubs.usgs.gov/imap/i1874/
For a general explanation of plutonic rocks,
click here.
Explanation of Symbols:
Qal: Quaternary Alluvium
Includes stream deposits, meadow deposits, and glacial outwash
(Quaternary)
Qtl: Talus (Holocene)
Rock waste derived from cliffs. Only especially extensive areas
shown
Qti: Tioga Till
Moraines usually sharp crested with abundant boulders at surface
(Pleistocene)
Qta: Tahoe Till
Moraines usually crested, but subdued, with scattered, weathered
boulders at surface.
Qpt: Pre-Tahoe Till
Moraines hummocky and dissected. May include Sherwin tills
(Pleistocene).
Khd: Half Dome granodiorite
Medium grained biotite hornblende granodiorite with conspicuous
crystals of sphene. Locally porphyritic with abundant large
phenocrysts of potassium feldspar. Age 86-88 Ma
Kkc: Granodiorite of Kuna Crest
Dark-colored, fine- to medium-grained, biotite-hornblende
granodiorite. Age 88 Ma
Ks: Sentinel Granodiorite
Coarse-grained, dark-gray, biotite-hornblende granodiorite with
abundant sphene. Age 93 Ma
Kbv: Bridalveil Granodiorite
Fine-grained hornblende-biotite granodiorite and granite.
Kic: Granodiorite of Illilouette Creek
Medium- to coarse-grained mafic hornblende-biotite granodiorite,
tonalite and granite. Age about 100 Ma
Kid: Quartz diorite
Dark fine-grained rock rich in hornblende. Occurs as irregular
intrusive masses cross-cutting El Capitan and Taft Granites on north
side of Yosemite Valley.
Kt: Taft Granite
Fine- to coarse-grained white to gray biotite granite and biotite
granodiorite. Locally porphyritic with phenocrysts of potassium
feldspar. Age 96 Ma
Kec: El Capitan Granite
Coarse-grained, white to light-gray biotite granite and biotite
granodiorite. Commonly porphyritic with blocky phenocrysts of
potassium feldspar and conspicuous quartz grains. Age about 102 Ma
Kga: Tonalite of the Gateway
Also known as Bass Lake Tonalite. Medium-grained
biotite-hornblende tonalite. Varies to granodiorite and quartz
diorite. Age 114 Ma
Kar: Granodiorite of Arch Rock
Medium-grained, biotite granodiorite, commonly with poikilitic
potassium feldspar. Age 116 Ma
KJdg: Diorite and gabbro
Occurs as generally small, irregularly shaped bodies throughout
map area, including the Rockslides adjacent to El Capitan. Age
Jurassic to Cretaceous
Jms: Metasedimentary rock
Hornfels and other metamorphic rocks. Jurassic (?)
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