Ogallala Formation
The Ogallala Formation is a Miocene to early Pliocene geologic formation in the central High Plains of the western United States and the location of the Ogallala Aquifer.[1] In Nebraska and South Dakota it is also classified as the Ogallala Group.[2] Notably, it records the North American Land Mammal Ages (NALMAs) Hemphillian, Clarendonian, and Barstovian.[3] It also includes an excellent record of grass seeds and other plant seeds, which can be used for biostratigraphic dating within the formation. The Ogallala Formation outcrops of Lake Meredith National Recreation Area preserve fish fossils.[4] Similar specimens from the same unit are found at Alibates Flint Quarries National Monument in Texas.[4]
| Ogallala Formation Stratigraphic range: Neogene | |
|---|---|
 Common appearance of the "caprock" caliche beds from the middle of the Ogallala at Ash Hollow, Nebraska | |
| Type | Formation / Group |
| Sub-units | Nebraska only: *Kimball (youngest) *Ash Hollow *Valentine (oldest) |
| Lithology | |
| Primary | sand, gravel, caliche cementation, marl, ash |
| Other | chert, opaline sandstone, limestone |
| Location | |
| Region | central High Plains |
| Country | United States |
| Type section | |
| Named for | Ogallala, Nebraska |
Gallery
East side of Blanco Canyon, TX, showing the locally red-colored Ogallala Formation and the bright white color of the Blanco Formation.
See also
References
- Footnotes
- Rex C. Buchanan, B. Brownie Wilson, Robert R. Buddemeier, and James J. Butler, Jr. "The High Plains Aquifer". Kansas Geological Survey, Public Information Circular (PIC) 18.CS1 maint: uses authors parameter (link)
- "Geologic Unit: Ogallala". National Geologic Database. Geolex — Significant Publications. United States Geological Survey. Retrieved 2020-06-05.
- Greg A. Ludvigson, Robert S. Sawin, Evan K. Franseen, W. Lynn Watney, Ronald R. West, and Jon J. Smith. "A Review of the Stratigraphy of the Ogallala Formation and Revision of Neogene ("Tertiary") Nomenclature in Kansas". Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 256, part 2.CS1 maint: uses authors parameter (link)
- "Lake Meredith National Recreation Area," Hunt, Santucci, and Kenworthy (2006); page 67.
- Sources
- Hunt, ReBecca K., Vincent L. Santucci and Jason Kenworthy. 2006. "A preliminary inventory of fossil fish from National Park Service units." in S.G. Lucas, J.A. Spielmann, P.M. Hester, J.P. Kenworthy, and V.L. Santucci (ed.s), Fossils from Federal Lands. New Mexico Museum of Natural History and Science Bulletin 34, pp. 63–69.
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