Formation · Cretaceous
Niobrara Formation
Late Cretaceous unit, Kansas · Nebraska · Colorado · South Dakota
The Niobrara Chalk of western Kansas is the marine counterpart to the dinosaur beds: mosasaurs, plesiosaurs, Pteranodon, the giant fish Xiphactinus, sharks and the flat inoceramid clams that pave the outcrop. Trade material is mostly shark teeth (Squalicorax, Cretolamna, Ptychodus crusher plates), fish vertebrae, Uintacrinus slabs and mosasaur teeth; complete skeletons are largely museum stock. The chalk is soft, so prepared specimens are usually consolidated and often reset in new matrix.
| Country | United States |
|---|---|
| Region | Kansas, Nebraska, Colorado, South Dakota |
| Age | Santonian, Late Cretaceous |
| Age range | ~87–82 Ma |
| Group | Colorado Group |
| Member | Smoky Hill Chalk Member |
| Macrostrat rank | Fm· Macrostrat |
| Macrostrat age | 93.9–72.2 Ma· Macrostrat |
| PBDB collections | 254 collections, 598 occurrences· Paleobiology Database |
Collecting and legality
The Smoky Hill Chalk badlands of Gove, Logan and Trego counties are almost entirely private ranch land; permission is required and most ranchers now charge or restrict access. Kansas has no state fossil law for private land, but vertebrate material from the few state and federal parcels cannot be sold.
Lithology and setting
Soft yellow-grey chalk and chalky shale laid down in the clear, deep centre of the Western Interior Seaway, with bentonite marker beds.
Commonly recorded taxa (PBDB)
Genera most often recorded from this unit in the Paleobiology Database (first 200 occurrences): Inoceramus (24), Baculites (13), Inoceramus (Cordiceramus) (13), Magadiceramus (13), Clioscaphites (10), Volviceramus (9), Platyceramus (8), Pseudoperna (7), Mytiloides (6), Cladoceramus (5), Cremnoceramus (5), Inoceramus (Volviceramus) (4), Prionocyclus (4), Ichthyornis (3), Niobrarateuthis (3).
Source: Paleobiology Database
Elsewhere
- Macrostrat: 72437
- macrostratConcept: 9529
- PBDB: strata:Niobrara
- Wikidata: Q7039335
- Macrostrat stratigraphic name
- PBDB occurrences for this unit
- Wikipedia: Niobrara Formation
- Mindat: Niobrara Formation
Cite this article
Stratum Study. "Niobrara Formation" (Formation). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/formations/niobrara-formation. Accessed 2026-09-20.
@misc{stratum-niobrara-formation,
title = {Niobrara Formation},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/formations/niobrara-formation}},
year = {2026},
note = {Formation article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, macrostrat, pbdb, wikidata, commons. Accessed 2026-09-20.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.