Temblor Range

The Temblor Range lies at the southwestern end of the San Joaquin Valley in California in the United States. It runs in a northwest-southeasterly direction along the borders of Kern County and San Luis Obispo County. The name of the range is from the Spanish word for earthquake. The San Andreas Fault Zone lies at the western edge of the range on the eastern side of the Carrizo Plain, while the Antelope Plain, location of the enormous Midway Sunset, South Belridge, and Cymric oil fields, lies to the northeast.

Peaks within the Temblor Range average about 3500 ft (1,100 m) above sea level. [ [http://www.britannica.com/eb/article-9099958/Temblor-Range "Temblor Range", Britannica.com] ] The highest point is McKittrick Summit at 4,331 ft (1,320 m), located in the center of the range about 35 mi (56 km) west of Bakersfield. [ [http://www.bartleby.com/69/86/T02386.html "The Columbia Gazetteer of North America"] ] The summit on State Route 58, which crosses the range, is at 3,750 feet above sea level.

Origin and composition

The Temblor Range and surrounding region contains extensive outcrops of the Monterey Formation (Miocene age, about 20 to 9 million years). Rocks from the Monterey formation consist mostly of silicate shales and porcellanite (silica derived from fossil plankton in an intermediate to deep-water marine setting). Fossils and sediments from the Monterey Formation show that the Carrizo Plain region was a marine basin with shallow to intermediate depths (marine waters covered the southern San Joaquin Valley region). Marine sediments younger than about 9 million years are not preserved in the Carrizo Plain National Monument area, but they occur throughout the Kettleman Hills region (about 60 miles north of the park) where the Etchegoin Formation contains marine fossils to about 4 million years old (Pliocene Epoch). Fossils of the Etchegoin Formation are supporting evidence that the Coast Ranges and the Temblor Range are young, having been uplifted mostly during the Pleistocene Epoch (or Quaternary Period) in the past couple million years. Much of that ongoing uplift is is due to tectonics associated with the San Andreas Fault and other fault systems in the region. [ [http://3dparks.wr.usgs.gov/carrizo/html/a093.htm United States Geological Survey] ]

During the Pleistocene, sometime more recently than 1.8 million years ago, an enormous block of the Temblor Range – a swath of Monterey shale more than six miles long, a mile across, and over 2,000 feet thick, about three cubic miles of rock in all – slid down the northeastern side of the range, covering a distance of approximately three miles and descending 2,000 feet. This mass movement completely covered the McKittrick Oil Field, giving it a highly unusual geology for an oil field, as most petroleum deposits are in structural or stratigraphic traps; this field is capped by an enormous mass of rock that moved off of the adjacent mountain range. [J.A. Taff: "Geology of the McKittrick Oil Field and Vicinity, Kern County, California." American Association of Petroleum Geologists Bulletin, 1933 [http://search.datapages.com/data/doi/10.1306/3D932B12-16B1-11D7-8645000102C1865D (abstract available here)] ]

References

*cite book|first=Stuart|last=Allan|title=California Road and Recreation Atlas|year=2005|publisher=Benchmark Maps|pages=p. 92|id=ISBN 0-929591-80-1

Notes

External links

* [http://3dparks.wr.usgs.gov/carrizo/ Carrizo Plain National Monument] - A 3D Photographic Tour Featuring Park Geology