Seven Rivers Formation

Seven Rivers Formation
Stratigraphic range: Guadalupian PreꞒ Ꞓ O S D C P T J K Pg N
Cliff of Seven Rivers Formation
Type	Formation
Unit of	Artesia Group
Underlies	Yates Formation
Overlies	Queen Formation
Thickness	400–1,970 feet (120–600 m)
Lithology
Primary	Anhydrite
Other	Shale, siltstone, dolomite (rock), sandstone
Location
Coordinates	32.497°N 104.256°W / 32.497; -104.256
Region	New Mexico
Country	U.S.
Seven Rivers Formation (the United States) Show map of the United States Seven Rivers Formation (New Mexico) Show map of New Mexico

The Seven Rivers 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.[1]

Description

The formation consists of 400–1,970 feet (120–600 m)[2][1] of anhydrite, with interbeds of shale, dolomite, siltstone, and sandstone. It rests on the Queen Formation 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.[1][3]

History of investigation

The unit was first named as the Seven Rivers Member of the (now abandoned) Chupadera Formation by Oscar Edward Meinzer and coinvestigators in 1927.[4] 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.[5] The unit was promoted to formation rank and assigned to the Whitehorse Group by Ronald K. DeFord and E. Russel Lloyd in 1940.[6] Norman D. Newell and coinvestigators assigned the formation to the (now abandoned) Carlsbad Group in 1953,[7] and it was assigned to the Artesia Group by D.B. Tait and coinvestigators in 1962.[1]

• 
  Shales and gypsum of the Seven Rivers Formation, Bottomless Lakes State Park, New Mexico
• 
  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

Footnotes

1. Tait, Motts & Spitler 1962.
2. Hayes & Koogle 1958.
3. Kues 2006.
4. Meinzer, Renick & Bryan 1927.
5. Lang 1937.
6. DeFord & Lloyd 1940.
7. Newell et al. 1953.

References

• DeFord, Ronald K.; Lloyd, E. Russel (1940). "West Texas-New Mexico Symposium: Part I Editorial Introduction". AAPG Bulletin. 24. doi:10.1306/3D933188-16B1-11D7-8645000102C1865D.
• Hayes, P.T.; Koogle, R.L. (1958). "Geology of the Carlsbad Caverns West quadrangle, New Mexico-Texas". U.S. Geological Survey Geologic Quadrangle Map. GQ-112.
• Kues, Barry S. (2006). "Geological studies of the Guadalupe Mountains area, New Mexico and West Texas, to 1928" (PDF). New Mexico Geological Society Field Conference Series. 57: 127–144. Retrieved 20 September 2020.
• Lang, W.B. (1937). "The Permian formations of the Pecos Valley of New Mexico and Texas". American Association of Petroleum Geologists Bulletin. 21 (7): 833–898. doi:10.1306/3D932EDE-16B1-11D7-8645000102C1865D.
• Meinzer, O.E.; Renick, B.C.; Bryan, Kirk (1927). "Geology of No. 3 reservoir site of the Carlsbad Irrigation Project, New Mexico, with respect to water tightness". U.S. Geological Survey Water-Supply Paper. 580-A.
• Newell, N.D.; Rigby, J.K.; Fischer, A.G.; Whiteman, A.J.; Hickox, J.E.; Bradley, J.S. (1953). The Permian reef complex of the Guadalupe Mountains region, Texas and New Mexico; a study in paleoecology. San Francisco: W.H. Freeman and Company. ASIN B001AQT3YC.
• Tait, D.B.; Motts, W.S.; Spitler, M.E. (1962). "Artesia Group of New Mexico and West Texas". American Association of Petroleum Geologists Bulletin. 46 (4): 504–517. doi:10.1306/BC74383B-16BE-11D7-8645000102C1865D.