# Tuerto Formation

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The **Tuerto Formation** is a [geologic formation](/source/Formation_(stratigraphy)) exposed around the [Ortiz Mountains](/source/Ortiz_Mountains) of [New Mexico](/source/New_Mexico). It is estimated to be of [Pliocene](/source/Pliocene) to [Pleistocene](/source/Pleistocene) age, and forms the gravel cap of the Ortiz surface, one of the first [pediment surfaces](/source/Pediment_(geology)) recognized by [geologists](/source/Geologist).

## Description

The Tuerto Formation consists primarily of [conglomerate](/source/Conglomerate_(geology)) with minor [sandstone](/source/Sandstone). The [clasts](/source/Clasts) (rock fragments) making up the conglomerate consist largely of [hornfels](/source/Hornfels) and [Ortiz porphyry](/source/Ortiz_porphyry_belt)[1] [eroded](/source/Eroded) off the [Ortiz Mountains](/source/Ortiz_Mountains) and [Cerrillos Hills](/source/Cerrillos_Hills) and deposited as a thin [alluvial fan](/source/Alluvial_fan) in the Hagan basin.[2] Beds containing [limestone](/source/Limestone) clasts eroded off the east slopes of the [Sandia Mountains](/source/Sandia_Mountains) are sometimes also included in the formation.[3] The formation is informally divided into a lower well-[cemented](/source/Cementation_(geology)) cliff-forming [member](/source/Member_(stratigraphy)) and an upper poorly cemented member.[2]

The formation lies with [angular unconformity](/source/Angular_unconformity) on the [Blackshare Formation](/source/Blackshare_Formation). It is distinguished from the coeval [Ancha Formation](/source/Ancha_Formation) in containing mostly volcanic clasts, while the Ancha Formation is rich in [granite](/source/Granite) clasts.[2]

The unit underlies the Ortiz surface, one of the first [pediment surfaces](/source/Pediment_(geology)) recognized, by I.H. Ogilvie in 1905.[4]

## History

The unit was first named the Tuerto Gravel by C.E. Stearns in 1953 for exposures southwest of [Santa Fe, New Mexico](/source/Santa_Fe,_New_Mexico).[5] Daniel Koning, Sean Connell, Frank Pazzaglia, and William McIntosh described the unit as the Tuerto formation in 2020,[2] and Connell first argued for formalizing it at formation rank in a footnote to a 2002 paper.[1] It was so treated in a draft geologic map of the Hagan area in 2002.[3]

## References

1. Connell et al. 2002.

1. Koning et al. 2001.

1. Cather et al. 2002.

1. Ogilvie 1905.

1. Stearns 1953.

### Bibliography

- Cather, Steven M.; Connell, Sean D.; Lucas, Spencer G.; Picha, Mark G.; Black, Bruce A. (June 2002). ["Geologic Map of the Hagan Quadrangle, Santa Fe County, New Mexico"](https://geoinfo.nmt.edu/publications/maps/geologic/ofgm/downloads/50/HaganReport.pdf). *New Mexico Bureau of Geology and Mineral Resources Open-file Digital Geologic Map*. **OF-GM 050**. Retrieved 17 August 2020.
- Connell, Sean D.; Cather, Steven M.; Dunbar, Nelia W.; McIntosh, William C.; Peters, Lisa (November 2002). ["Stratigraphy of the Tanos and Blackshare Formations (lower Santa Fe Group), Hagan embayment, Rio Grande rift, New Mexico"](https://geoinfo.nmt.edu/publications/periodicals/nmg/24/n4/nmg_v24_n4_p107.pdf). *New Mexico Geology*. **24** (4). Retrieved 9 June 2020.
- Ogilvie, I.H. (1905). "The high-altitude conoplain: a topographic form illustrated in the Ortiz Mountains". *American Geologist*. **22**
- Koning, Daniel; Connell, Sean; Pazzaglia, Frank; Mcintosh, William (2001). ["Stratigraphy of the Tuerto and Ancha Formations (upper Santa Fe Group), Hagan and Santa Fe Embayments, north-central New Mexico"](https://geoinfo.nmt.edu/publications/openfile/downloads/400-499/454/papers/OFR454B_pdf/I-Koning_Ancha-Tuerto_final.pdf). *New Mexico Bureau of Mines and Mineral Resources Open File Report*. **454B**. Retrieved 17 August 2020.
- Stearns, Charles E. (1953). "Tertiary geology of the Galisteo-Tonque area, New Mexico". *Geological Society of America Bulletin*. **64** (4): 459. [Bibcode:1953GSAB...64..459S](https://ui.adsabs.harvard.edu/abs/1953GSAB...64..459S). [doi:10.1130/0016-7606(1953)64\[459:TGOTGA](https://doi.org/10.1130/0016-7606(1953)64%5B459:TGOTGA%5D2.0.CO;2)2.0.CO;2]

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Adapted from the Wikipedia article [Tuerto Formation](https://en.wikipedia.org/wiki/Tuerto_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Tuerto_Formation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.