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The Franciscan Assemblage is a geological term for a heterogeneous assemblage of rocks found on and near the San Francisco Peninsula. The Blue Marble: The famous photo of the Earth taken en route to the Moon by Apollo 17s Harrison Schmitt on December 7, 1972. ...
Sedimentary, volcanic, plutonic, metamorphic rock types of North America. ...
USGS Satellite photo of the San Francisco Bay Area. ...
Also known as the "Franciscan Formation," "Franciscan Series," "Franciscan Group," "Franciscan assemblage," or "Franciscan Complex," it includes altered mafic volcanic rocks (greenstones), deep-sea cherts, greywacke sandstones, limestones, serpentinites, shales, and high-pressure metamorphic rocks, all of them faulted and mixed in a seemingly chaotic manner. In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ...
A smoke plume from Mount Ubinas, Peru, the most historically active volcano in that nation. ...
Chert Chert is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. ...
Greywacke (German grauwacke, signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly-sorted, angular grains of quartz, feldspar, and small rock fragments set in a compact, clay-fine matrix. ...
Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ...
Limey shale overlaid by limestone. ...
Serpentinite is a rock comprised of an admixture of serpentine minerals. ...
Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ...
Metamorphic rock is the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means change in form (from the Greek prefix meta, after, and the noun morphe, form). The protolith is subjected to heat (greater than 150 degrees Celsius) and extreme...
Old fault exposed by roadcut near Harrisburg, Pennsylvania. ...
It forms the major component of the Pacific Coast Ranges of California. The Pacific Coast Ranges are the series of mountain ranges that stretch along west coast of North America from Alaska to Mexico. ...
Official language(s) English Capital Sacramento Largest city Los Angeles Area Ranked 3rd - Total 158,302 sq mi (410,000 km²) - Width 250 miles (400 km) - Length 770 miles (1,240 km) - % water 4. ...
Wentworth and others (1984) interpreted the juxtaposition of the Franciscan Assemblage and the section consisting of the Coast Range ophiolite and the Great Valley sequence to have happened through landward movement of the Franciscan Assemblage as a tectonic wedge. Ophiolites are sections of oceanic lithosphere that have been uplifted or emplaced to be exposed within continental crustal rocks. ...
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References
- Wentworth, C. M., Blake, M. C. Jr., Jones, D. L., Walter, A. W., and Zoback, M. D. 1984. Tectonic wedging associated with emplacement of the Franciscan assemblage, California Coast Ranges. In Blake, M.C., ed., Franciscan geology of northern California. Pacific Section, Society of Economic Paleontologists and Mineralogists, Field Trip Guidebook 43, p. 163-173.
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