California Granitic Rock Formation

It forms from the slow crystallization of magma below earth s surface.

California granitic rock formation. The formation was named el capitan by the. Igneous rocks from the greek word for fire form when hot molten rock magma crystallizes and solidifies. Magma that rises to the surface is called lava. Different granites have unique chemical compositions that produce different mineral proportions.

These ancient rocks that formed the earliest vestiges of what is now san diego county. Introduction california s geologic history is very complex most of the state did not exist as a coherent piece of the earth s crust until relatively recently in geologic terms. Hiding in the northern region of the sierra nevada is a rocky outcropping that is not only impressive in itself but boasts the perfect vantage point of the surrounding landscape. Strictly speaking granite is an.

Granite is composed mainly of quartz and feldspar with minor amounts of mica amphiboles and other minerals this mineral composition usually gives granite a red pink gray or white color with dark mineral. Felsic rocks are less dense than mafic and ultramafic rocks and thus they tend to escape subduction whereas basaltic or gabbroic rocks tend to sink into the mantle beneath the granitic rocks of the continental cratons. Granite ˈ ɡ r æ n ɪ t is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Therefore granitic rocks form the basement of all land continents.

Rock formations that are now adjacent often have very different histories. The idaho batholith forms one of the largest areas of massive granitic rock in the united states covering most of the red shaded area in fig. In fact granitic rocks are generally classified by their mineral proportions and given names such as granite granodiorite tonalite and diorite. Photo by eva didonato.

Looking at a granitic rock s composition tells geologists much about its formation. Some of the larger collisions were associated with major episodes of tectonic activity intrusive and extrusive volcanic. Enjoy expansive views from atop a granite batholith at northern california s big bald rock. The first arc exposed along the winding stretches of sunrise highway s 1 in the central part of san diego county is a north northwest trending belt of granitic rocks called the cuyamaca laguna mountain shear zone clmsz.

Granite is a light colored igneous rock with grains large enough to be visible with the unaided eye. Granites can be predominantly white pink or gray in color depending on their mineralogy the word granite comes from the latin granum a grain in reference to the coarse grained structure of such a completely crystalline rock. Magma originates deep within the earth near active plate boundaries or hot spots. The captain or the chief also known as el cap is a vertical rock formation in yosemite national park located on the north side of yosemite valley near its western end the granite monolith is about 3 000 feet 914 m from base to summit along its tallest face and is a popular objective for rock climbers.