| Valentine Formation | |
|---|---|
| Stratigraphic range: | |
 Looser sand of the Valentine Formation sloping back from its contact with the Rosebud Formation on the Niobrara River at the Valentine, Nebraska, type location. Water from the Ogallala Aquifer seeps from the base of the Valentine down the face of the Rosebud.[1] | |
| Type | Formation / Member |
| Unit of | Ogallala Formation |
| Overlies | Eroded and weathered Miocene units, Pierre Shale (Nebraska), and Niobrara Chalks |
| Location | |
| Region |  South Dakota,  Nebraska,  Kansas |
| Country |  United States |
| Type section | |
| Named for | Valentine Railway Quarries, Valentine, Nebraska |
The Valentine Formation is a geologic unit formation or member within the Ogallala unit in northcentral Nebraska near the South Dakota border. It preserves fossils dating to the Miocene epoch of the Neogene period and is particularly noted for Canid fossils.[2][3] This unit consists of loosely-consolidated sandstone that crumbles easily. These sands carry the water of the Ogallala Aquifer and is the source of much of the water in the Niobrara River.[1] A particular feature of the Valentine is lenticular beds of green-gray opaline sandstone that can be identified in other states, including South Dakota, Nebraska, Kansas, and Colorado. Although three mammalian fauna stages can be mapped throughout the range of the Ogallala, no beddings of the Ogallala are mappable and all attempts of formally applying the Valentine name to any mappable lithology beyond the type location have been abandoned. Even so, opaline sandstone[4] has been used to refer to this green-gray opalized conglomerate sandstone that is widely found in the lower Ogallala Formation.
- ^ a b "Geologic Formations". Niobrara National Scenic River. National Park Service. Retrieved 2024-02-24.
Valentine Formation -- Beneath the Ash Hollow is the Valentine Formation. This loosely-consolidated sandstone crumbles easily, but holds the primary source of the Niobrara River in this area: the Ogallala, or High Plains, aquifer. About 70% of the water in the river comes directly from groundwater.
- ^ Robert L. Evander, Emanuel County Junior College (1986). "Carnivores of the Railway and Quarries Local Fauna". Transactions of the Nebraska Academy of Sciences and Affiliated Societies Nebraska Academy of Sciences. University of Nebraska - Lincoln.
- ^ "Geologic Unit: Valentine". National Geologic Database. Geolex — Significant Publications. United States Geological Survey. Retrieved 2020-06-05.
- ^ Cite error: The named reference
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