Unlike other rivers on the Great Plains, the Niobrara is rapidly eroding (on a geologic time scale), cutting down into ancient formations that formerly lay buried beneath the river. The result is that the river is confined to a narrow valley over much of its designated 76-mile length, with high cliffs looming over portions of the river, and rocks and rapids greeting canoers. Ponderosa pine grow next to paper birch, and deep tributary canyons often hide waterfalls and species characteristic of northern climes. Further downstream, the river and valley spread out and provide habitat for endangered birds and nesting bald eagles.
Although the Niobrara National Scenic River is comprised mostly of private land, the Fort Niobrara National Wildlife Refuge and Niobrara Valley Preserve protect much of the area. Additional protection comes from Smith Falls State Park, which holds Nebraska’s highest waterfall at 65 feet, and Borman Bridge and Fred Thomas Wildlife Management Areas, which permit additional public access.
May 24, 1991. From Borman Bridge to State Highway 137. From the western boundary of Knox County to its confluence with the Missouri River. Verdigre Creek from its confluence with the Niobrara to the north boundary of the town of Verdigre.
The permanent water source provided by the Niobrara River and Verdigre Creek segments attracted significant prehistoric and historic use. The water provides a great diversity and abundance of vegetation and animal resources today as it did in the past. Wild food gathering, hunting, trapping, and fishing remain important activities. These same resources made it an attractive homeland for Ponca farmers and the subsequent homesteaders. The historic Ponca Agency and its cemetery are examples of the continuing use of the area by the Ponca community. Mormon Monument near Niobrara State Park commemorates the Mormon emigrants who perished during the winter of 1846 as they traveled west. The grist mill near Verdigre Creek remains an excellent example of early European settlement in the region.
The dynamic Niobrara River is a naturally braided stream in the Great Plains that has outstanding channel complexity and large woody debris. The river is connected to its floodplain and naturally moves across the valley. This reach contains numerous backwaters, chutes, sandbars, islands, and wetlands that support multiple special status species, including the federally endangered interior least tern and the threatened piping plover. The federally endangered pallid sturgeon has also been documented in the lower Niobrara River. This river segment contains some mature cottonwood forests and sandbars that provide potential habitat for cottonwood regeneration and ideal nesting habitat for endangered least tern and threatened piping plover.
The middle Niobrara River Valley has been termed the “biological crossroads of the Great Plains.” Six divergent ecological communities occur in this narrow band of river valley. Western pine forest occurs on the dry south-facing canyon slopes. In contrast, the north-facing slopes are often shaded and are fed by an ample supply of groundwater; this has maintained eastern deciduous forest species. More unusual is the northern boreal forest, found in the deep, cool “spring-branch” canyons on the south side of the river. Here are relicts of the last ice-age, including paper birch and hybrid aspens. South of the river lies the Sandhills, almost exclusively covered by grass and herbs, some uniquely adapted to sand. North of the river is the northern mixed-grass prairie, characterized by finer-textured soils and shorter grasses. Finally, in little slivers on the floodplain, are elements of tallgrass prairie, big bluestem, switchgrass, and Indiangrass. The profusion of habitats and animal species become an outstanding example of Great Plains biological diversity. The river is doubly unique in that it serves as an ecological crossroads for several species of fish, birds, mammals, reptiles, and invertebrates, and a major area for hybridization and evolution. As well, portions of the river are important as potential critical habitat for several threatened or endangered species.
The dynamic and evolved geology of the Niobrara Valley is a delicate mix of well-watered, shady, and cool north-facing gradients; wider, sun-drenched south facing slopes; the diversity of a riverbed flowing variously over rock and sand substrate; and the tumble of water over hard rock. In their abundance and unexpected variety, the waterfalls of the Niobrara alone are unique to both Nebraska and the Great Plains. Most “geology” in the Great Plains lies out of sight, deep beneath the soil. But because this is a deeply entrenched river, its various geologic formations lie exposed in the cliffs flanking the river. The escarpment on the north side of the valley is a good place to view the lateral exposure of the Ash Hollow Formation (6-11 million years old). Below that is the Valentine Formation, largely composed of unconsolidated sand which was deposited 12-13.5 million years ago. Water from the Ogallala Aquifer flows out and over the face of the underlying Rosebud Formation (24-28 million years old) and forms numerous springs and waterfalls. The Rosebud, a pinkish-tan siltstone, is predominately seen from the river in the form of cliffs, but also forms much of the upper riverbed itself. Pierre Shale is the lowest (oldest) formation exposed in the scenic river, usually in the form of cliffs. It was formed in a marine environment 70-76 million years ago.
Fossils were first observed here in the mid-1800s, and paleontologists from the east started coming soon after. The most fossiliferous formation is the Valentine Formation. Mammals and other vertebrates from the Miocene left considerable evidence of their being. Dozens of fossil quarries have been identified, mostly on private land. One holds fossils of more species of mammals than any other in the world. The Ash Hollow also has fossils, such as early camels. Pleistocene-age river terraces also may contain any of the above, but also mastodon and mammoth. Petrified wood and other plant fossils are also common.
Given the unusual nature of the valley, and the river’s relatively rapid flow, tens of thousands of annual visitors come for an experience unique on the Great Plains. Canoes and tubes are the chosen means of enjoying the river. Floaters may supply their own or rent vessels from one of several outfitters. The stretch through the Fort Niobrara National Wildlife Refuge provides a quieter float and permits hiking into a federal wilderness area. Further downriver, one will find more river users and more of a party atmosphere on most summer weekends. Minor rapids may provide a challenge but can usually be avoided if desired. Even further downstream, the river spreads over sandbars, providing a different kind of challenge but with nearly complete seclusion.
The river runs easterly down a narrow, steep-walled valley for much of its length, with views of deciduous forests and ponderosa pine woodlands alternating with vistas of prairies and marshes. Narrow side canyons on the south side of the river invite exploration; most harbor waterfalls. However, some waterfalls plunge directly into the river, adding to the recurrent sound of tumbling and falling water. High cliffs, not typically seen on the Great Plains, lead the eye up to precariously perched pine and birch. Varied habitats support an abundance and diversity of wildlife, adding color and movement. Wildflowers and other plants bend over the riverbank. Wind and birdsongs compliment the scenery. Four full seasons add additional variation in activity, shape, color, and weather.