Decomposed granite of silica sand, silt particles, and clay. Different specific granite types have differing propensities to weather, and so differing likelihoods of producing decomposed granite. The parent granite material is a common type of igneous rock that is granular, with its grains large enough to be distinguished with the unaided eye (i.e., it is phaneritic in texture); it is composed of plagioclase feldspar, orthoclase feldspar, quartz, mica, and possibly other minerals. The chemical transformation of feldspar, one of the primary constituents of granite, into the clay mineral kaolin is one of the important weathering processes. The presence of clay allows water
El Capitan Granite 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 the granite found in the west half of the Yosemite Valley area. El Capitan Granite intruded older plutonic rocks about 103 Ma, during the Cretaceous Period. 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