Representing the largest inland dunefield in the Western Hemi-sphere, the Nebraska Sandhills cover the west-central portion of the State. Viewed from the air, one would expect that they are the remnants of a large lake or sea, their ridges of sand alternating with wetland valleys. In fact, they are a "recent" addition to the landscape, having formed within the last 12,000 years (after the retreat of the Pleistocene Glaciers). Geologists have documented that the dunes were deposited as windblown sand and sit atop rock sediments that can be more accurately dated to the late Tertiary Period. Furthermore, their studies reveal that the dunes have shifted their position a few times; presumably, periods of drought caused the anchoring vegetation to die off and permitted the ever-present wind to move the dunes.
Today, drought-tolerant grasses such as Indian grass, sand love, blowout grass and prairie sand reed stabilize the dunes; cedars also grow on the lower slopes. Any precipitation that falls on the dunes quickly trickles down to their base, feeding the Ogallala Aquifer that lies just below them; in turn, springs from the Aquifer produce chains of wetlands, ponds, riparian woodlands, lakes and wet meadows within the valleys. This rich, wetland ecosystem is home to beaver, muskrat, mink, waterfowl, waders, riparian songbirds and a variety of reptiles and amphibians. Greater prairie chickens favor the tallgrass of the valleys while sharp-tailed grouse hunt across the shortgrass of the dunes. Other prairie residents include long-billed curlews, upland sandpipers, meadowlarks, killdeer, northern harriers and coyotes.
Should you visit the Nebraska Sandhills, plan a visit to the Valentine National Wildlife Refuge, which straddles U.S. 83, 25 miles south of Valentine. In addition to many of the above species, April visitors have a good chance of seeing migrant sandhill cranes, American white pelicans, bald eagles and prairie falcons. This is also the breeding season for the grouse and prairie chickens; the "booming" display of the males is best observed at dawn.