Pasadena orogeny
File:Digital-elevation-map-so california.svg
Pasadena orogeny is a mountain building event in the Western United States. Conventionally it refers to the formation of mountains in mainly Southern California during the Pleistocene and lasting until the present day; originally it referred to the uplift of the San Gabriel Mountains.
The Pasadena orogeny is a major Late Quaternary-modern event{{sfn|Bohannon|Gardner|2004|p=261}} of mountain formation, which took place in the middle or perhaps late Pleistocene or to the present-day. It is also known as the "Coast Ranges orogeny" or considered to be part of the Cascadian orogeny or Alpide Orogeny.{{sfn|Stille|1936|p=875}} Finally, the term "Pasadena orogeny" is sometimes applied to all very recent orogenies around the Pacific Ocean.{{sfn|Stille|1936|p=849}} The type location is close to Pasadena, California in the Transverse Ranges,{{sfn|Blakey|Ranney|2017|p=186}} and originally referred to the fast rise of the San Gabriel Mountains recorded there.{{sfn|Blakey|Ranney|2017|p=183}}
During this orogeny mountain ranges such as the San Bernardino Mountains, San Gabriel Mountains, San Jacinto Mountains, Santa Monica Mountains, Santa Ynez Mountains{{sfn|Blakey|Ranney|2017|p=31}} and the Transverse Ranges grew, as did the northern Channel Islands{{sfn|Blakey|Ranney|2017|p=31}} such as Catalina Island and San Clemente Island, the Kettleman Hills anticline in the San Joaquin Valley{{sfn|Stille|1936|p=869}} and the Palos Verdes Hills. Sometimes the concept is limited to the uplift of the Transverse Ranges.{{sfn|Blakey|Ranney|2017|p=197}}
The general uplift of mountains over a length of over {{convert|400|km}} is caused by the collision of the North American Plate with other geologic structures that are attached to the Pacific Plate.{{sfn|Blakey|Ranney|2017|p=31}} This orogeny has resulted in the uplift of mostly north-south trending mountain chains, although some east-west trending uplifts are also found such as the Channel Islands and the Transverse Ranges;{{sfn|Stille|1936|p=869}} much of the uplift took place at the edge of basins.{{sfn|Blakey|Ranney|2017|p=181}} The Pasadena orogeny is accompanied by earthquake activity, which includes tsunami hazards.{{sfn|Bohannon|Gardner|2004|p=262}}
Folding accompanying the uplift of the Coast Ranges in Southern California, folding farther north at Morro Bay{{sfn|Blakey|Ranney|2017|p=184}} and the structure of the Santa Barbara Basin and Ventura Basin are consequences of the Pasadena orogeny. The city of Long Beach, California lies within the affected region.{{sfn|Bohannon|Gardner|2004|p=261}}
References
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= Sources =
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- {{Cite book|title=Ancient landscapes of western North America : a geologic history with paleogeographic maps|year=2017|last1=Blakey|first1=Ronald C.|last2=Ranney|first2=Wayne|isbn=9783319596365|location=Cham, Switzerland|oclc=1005353728}}
- {{cite journal |last1=Bohannon |first1=Robert G |last2=Gardner |first2=James V |title=Submarine landslides of San Pedro Escarpment, southwest of Long Beach, California |journal=Marine Geology |date=January 2004 |volume=203 |issue=3–4 |pages=261–268 |doi=10.1016/S0025-3227(03)00309-8 |language=en |issn=0025-3227|bibcode=2004MGeol.203..261B }}
- {{Cite journal|last=Stille|first=Hans|date=1936|title=The Present Tectonic State of the Earth|url=http://archives.datapages.com/data/bulletns/1931-37/data/pg/0020/0007/0800/0849.htm|journal=AAPG Bulletin|language=en-US|volume=20|issue=7|issn=0149-1423}}
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Category:Orogenies of North America
Category:Natural history of California