Sisquoc Formation at the stairs to More Mesa Beach, Santa Barbara, California
Type
Sedimentary
Underlies
Pico Formation, Santa Barbara Formation, others
Overlies
Monterey Formation
Thickness
Up to 1000 feet in Santa Barbara area; 1100 feet at type locality; up to 5000 feet south of Lompoc.[1][2][3]
Lithology
Primary
mudstone, shale, diatomite
Other
conglomerate
Location
Region
Southern California
Country
United States
Type section
Named for
Sisquoc River, about 10 miles southeast of Santa Maria, California
Named by
Porter (1932)[4]
Wikimedia Commons has media related to Sisquoc Formation.
The Sisquoc Formation is a sedimentary geologic unit widespread in Southern California, both on the coast and in mountains near the coast. Overlying the Monterey Formation, it is of upper Miocene and lower Pliocene age (from about 4 to 6 million years old).[5] The formation consists of claystone, mudstone, siltstone, shale, diatomite, and conglomerates, with considerable regional variation, and was deposited in a moderately deep marine environment at a depth of approximately 500–5,000 feet (150–1,520 m). Since some of its diatomites, along with those of the underlying Monterey Formation, are of unusual purity and extent, they can be mined as diatomaceous earth. France-based Imerys operates a mine in the Sisquoc and Monterey Formations in the hills south of Lompoc, California, the largest such operation in the world.[6][7]
^Minor, S.A., Kellogg, K.S., Stanley, R.G., Gurrola, L.D., Keller, E.A., and Brandt, T.R., 2009, Geologic Map of the Santa Barbara Coastal Plain Area, Santa Barbara County, California: U.S. Geological Survey Scientific Investigations Map 3001, scale 1:25,000, 1 sheet, pamphlet, 38 p.
^Dibblee, Thomas. Geology of the central Santa Ynez Mountains, Santa Barbara County, California. Bulletin 186, California Division of Mines and Geology. San Francisco, 1966. 51.
^Dibblee, Thomas. Geology of Southwestern Santa Barbara County, California. State of California, Department of Natural Resources, Division of Mines, Bulletin 150. 1950. 43.
^Dibblee, 1966. 51.
^Isaacs, Caroline M. and Rullkötter, Jürgen. The Monterey Formation: From Rocks to Molecules. Columbia University Press, 2001. ISBN 0-231-10585-1 p. 211.
^Abramson, Mark (July 23, 2005). "Celite World Minerals sells for 217 million". Lompoc Record. Retrieved October 23, 2010.
^Palmer, Lex. "Post-Chumash History of the Gaviota Coast". Gaviota Coast Conservancy.
Wikimedia Commons has media related to SisquocFormation. The SisquocFormation is a sedimentary geologic unit widespread in Southern California, both...
hundred meters thick in places. Marine deposits have been worked in the SisquocFormation in Santa Barbara County, California near Lompoc and along the Southern...
relationship with other rock formations in Southern California, although Thomas Dibblee has identified it as a member of the SisquocFormation. A small remnant California...
trapping mechanisms. In the West Area, oil is present in the overlying SisquocFormation in several sand units, in stratigraphic traps – pinched out within...
a shallower, neglected reservoir, primarily the contained in the SisquocFormation. When the major oil companies – Union, Conoco, Shell, and others –...
Paso Robles and Careaga formations are Pleistocene sediments. Underneath them is the relatively impermeable SisquocFormation, of Pliocene and Miocene...
Sisquoc is a ridge known as Hurricane Deck, a rugged 15-mile (24 km) slab of upthrust sandstone with a trail snaking along the top. Rock formations in...
units are the Sisquoc, Careaga, and Foxen formations. The Careaga and Foxen are of Pliocene age, while the thicker, diatomaceous Sisquoc is both Pliocene...
700 feet. Above the reservoir are the non-oil-bearing Sisquoc, Foxen, and Paso Robles formations. Oil in the reservoir is in the "extra heavy" range, with...