Brule Formation
| Brule Formation Stratigraphic range: Rupelian | |
|---|---|
| Type | Geological formation |
| Underlies | Sharps Formation, Arikaree Formation |
| Overlies | Chadron Formation |
| Thickness | 6 to 65 m.[1] |
| Lithology | |
| Primary | Fine grained clastic rocks |
| Other | Freshwater limestone, Tuff, Sandstone |
| Location | |
| Region | North Dakota, South Dakota |
| Country | USA |
The Brule Formation was deposited between 34 to 30 million years ago, roughly the Rupelian (Oligocene).[2] It is a sequence of fine grained clastic rocks (claystones, mudstones, siltstones) interbeded with freshwater carbonates, volcanic ash (tuff), and sandstone.[1]
The sandstones layers, which are up to 3 m thick, can contain mammalian fossils (e.g. the Fitterer bed). The most important fossils sites are:[1]
- Fitterer Ranch
- Obritsch Ranch
- Little Badlands in Stark County
- Chalky Buttes (including White Butte) in Slope County
Cat fish and sunfish fossils are known from the Brule Formation in Badlands National Park.[3]
References
- ↑ 1.0 1.1 1.2 "Lithostratigraphy, Paleontology, and Biochronology of the Chadron, Brule, and Arikaree Formations in North Dakota". Retrieved 28 February 2013.
- ↑ "Geologic Formations". nps.gov.
- ↑ 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.