Niobrara National Scenic River protects a 120 km (76 mi) stretch of the Niobrara River in Brown, Cherry, Keya Paha and Rock Counties, northern Nebraska. Authorized on May 24, 1991, it covers about 11,776 hectares (29,101 acres), from Borman Bridge near Valentine down the Niobrara River Valley to Mariaville, and is valued for outstanding ecological, scenic, recreational, cultural and scientific resources.
Fort Falls Overlook in the Fort Niobrara National Wildlife Refuge. Image from the National Park Service's page on the river's geodiversity
A river that changes downstream
- Upstream, in the west, the river runs through narrow canyons with steep, eroded bluffs. Going downstream, they progressively widen and round off.
- East of Norden Bridge the river itself changes, becoming more braided and seasonally shallow.
Along the way it supports many biologically diverse ecosystems: tallgrass, sandhills and mixed-grass prairies, and northern boreal, eastern deciduous and western coniferous forests.
The rocks
The river lies in the Nebraska Sand Hills and the Dakota–Nebraska Eroded Tableland of north-central Nebraska — mixed-grass prairie and some of the largest sand dunes in the Western Hemisphere — in the Great Plains Physiographic Province. Its bedrock is Mesozoic and Cenozoic, laid down in ancient seas, rivers and winds.
| Age | Rocks | Where |
|---|---|---|
| Oldest — Cretaceous | Pierre Shale: marine shales, siltstones and sandstones | the dark gray river bluffs in the east |
| Oligocene | sedimentary rocks correlated with the White River Group | the west |
| Miocene | the Ogallala Group (Ash Hollow and Valentine Formations) and the Rosebud Formation | the west |
| Youngest — Quaternary | loose terrace deposits, linear dunes, alluvium and colluvium | mapped across the river corridor |
Bluffs along the Niobrara in autumn. Image from the National Park Service's page on the river's geodiversity
Maps and surveys
The NPS Geologic Resources Inventory, which makes digital geologic maps and reports for more than 270 natural resource parks, has products for Niobrara in the NPS DataStore, and an NPS Soil Resources Inventory of the river has been completed (DataStore).
More from the park: natural features and ecosystems · geologic formations · fossils · waterfalls and springs · Great Plains Province.
Sources
Based on "NPS Geodiversity Atlas—Niobrara National Scenic River, Nebraska," National Park Service, citing National Park Service (2016), Skinner and Johnson (1984), Swinehart and others (1994) and Joeckel and others (2015, 2016); a work of the United States government in the public domain.
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