Poway Group
Stratigraphic range: Paleogene
TypeGroup
Sub-unitsStadium Conglomerate, Mission Valley Formation, Pomerado Conglomerate
Location
RegionSan Diego County, California
CountryUnited States

The Poway Group is a geologic group in San Diego County, Southern California. It preserves fossils dating back to the Paleogene period.[1]

Poway clasts

Volcanic clastic rock cobbles of rhyolite, in a sandstone matrix in this area are named Poway clasts.[2]

The ancient Ballena River brought rhyolite-gravel, or “Poway" clasts, from a region in present-day Sonora, Mexico to the Pacific Ocean. Its sediments deposited into alluvial fan-submarine canyon-submarine fan complex extending for miles offshore. Remnants of submarine fan facies outcrops are found as far west as the northern Channel Islands. Inland Ballena River deposits outcrop discontinuously over 16 miles (26 km) in a west-southwest trend from Whale Mountain to San Vicente Reservoir, here the river was up to 2 miles (3.2 km) in width through Peninsular Ranges.[3]

Stratigraphy

Kennedy and Moore (1971) describe a stratigraphy of up to three geologic formations, Stadium Conglomerate, Mission Valley Formation, and the later named Pomerado Conglomerate. The basal unit is the Stadium Conglomerate. The Stadium Conglomerate is overlain by the Mission Valley Formation.[4] The Mission Valley Formation is overlain by the Pomerado Conglomerate.[5]

See also

References

  1. ↑ Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.
  2. ↑ San Diego Mesa College: Tecolote Canyon: A Geologic Overview Archived 2015-07-10 at the Wayback Machine — with Poway Clasts image.
  3. ↑ Geiconsultants.com: "Geologic Formations of Western San Diego County", by Jeffrey D. Brown, R.G., C.E.G., GEI Consultants, Inc. − c.1996.
  4. ↑ Michael P. Kennedy; George W. Moore (1971). "Stratigraphic Relations of Upper Cretaceous and Eocene Formations, San Diego Coastal Area, California". AAPG Bulletin. 55 (5): 709–722, 709–722. doi:10.1306/819A3C5A-16C5-11D7-8645000102C1865D. ISSN 0149-1423. Wikidata Q63565588.
  5. ↑ Gary L. Peterson; Michael P. Kennedy (1974). "Lithostratigraphic variations in the Poway Group near San Diego, California". Transactions of the San Diego Society of Natural History. 17 (18): 251–257. ISSN 0080-5947. Wikidata Q64769086.


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