The Seven Rivers Formation is a
geologic formation in southeastern
New Mexico and west
Texas. It preserves
fossils
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
dating back to the late
Guadalupian Epoch of the
Permian period.
Description
The formation consists of of
anhydrite, with interbeds of
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
,
dolomite Dolomite may refer to:
*Dolomite (mineral), a carbonate mineral
*Dolomite (rock), also known as dolostone, a sedimentary carbonate rock
*Dolomite, Alabama, United States, an unincorporated community
*Dolomite, California, United States, an unincor ...
,
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
, and
sandstone. It rests on the
Queen Formation
The Queen Formation is a geologic formation in southeastern New Mexico and west Texas. It preserves fossils dating back to the late Guadalupian Epoch of the Permian period.
Description
The formation consists of up to of mostly sandstone, with so ...
and is overlain by the
Yates Formation. The Seven Rivers Formation is part of the
Artesia Group, which is interpreted as a sequence of shelf rocks of the
Capitan reef.
History of investigation
The unit was first named as the Seven Rivers Member of the (now abandoned) Chupadera Formation by
Oscar Edward Meinzer
Oscar Edward Meinzer (November 28, 1876 – June 14, 1948) was an American hydrogeologist who has been called the "father of modern groundwater hydrology". He was awarded the William Bowie Medal
The William Bowie Medal is awarded annually by t ...
and coinvestigators in 1927. In 1937, W.B. Lang assigned the Seven Rivers Member to the (now abandoned) Chalk Bluff Formation and removed its upper beds to the Three Twins Member. The unit was promoted to formation rank and assigned to the Whitehorse Group by Ronald K. DeFord and E. Russel Lloyd in 1940.
Norman D. Newell
Norman Dennis Newell (January 27, 1909 – April 18, 2005) was professor of geology at Columbia University, and chairman and curator of invertebrate paleontology at the American Museum of Natural History in New York City.
Personal life
Newell was ...
and coinvestigators assigned the formation to the (now abandoned) Carlsbad Group in 1953, and it was assigned to the
Artesia Group by D.B. Tait and coinvestigators in 1962.
File:7 Rivers Fm.jpg, Shales and gypsum of the Seven Rivers Formation, Bottomless Lakes State Park, New Mexico
File:7 Rivers Gypsum.jpg, Weathered face of gypsum in the Seven Rivers Formation, Bottomless Lakes State Park, NM. Note the dark, irregular reprecipitated gypsum
See also
*
List of fossiliferous stratigraphic units in New Mexico
*
Paleontology in New Mexico
Paleontology in New Mexico refers to paleontological research occurring within or conducted by people from the U.S. state of New Mexico. The fossil record of New Mexico is exceptionally complete and spans almost the entire stratigraphic column. ...
Footnotes
References
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* {{cite journal , last1=Tait , first1=D.B. , last2=Motts , first2=W.S. , last3=Spitler , first3=M.E. , year=1962 , title=Artesia Group of New Mexico and West Texas , journal=American Association of Petroleum Geologists Bulletin , volume=46 , number=4 , pages=504–517 , doi=10.1306/BC74383B-16BE-11D7-8645000102C1865D
Permian formations of New Mexico