Editor’s Note: Today’s story is the answer to the June Puzzler.
The undulating landscape of north-central Nebraska may be easy to overlook among the iconic dune fields of the world. Far from any coast or desert, the Nebraska Sandhills—comprising the Western Hemisphere’s largest system of sand dunes—bring their own brand of beauty and value. Grasslands blanket the rolling hills, providing grazing grounds for livestock, while lakes and wetlands dot the landscape, supporting diverse plant and animal life.
Much of the sand forming the hills originated in the Rocky Mountains. Rivers carried the eroded material down from the mountains and deposited it across the Great Plains during the Pleistocene. In times of drought, winds blowing predominantly from the north or south lofted sand out of dried riverbeds, gradually building and shaping dunes. About 3,500 years ago, grassland vegetation stabilized the features. Today, the rippled pattern spans about 20,000 square miles (52,000 square kilometers), about one-quarter of the state of Nebraska.
Some of the largest dunes occur in and around the area shown in the detailed image above, near the northern edge of the Sandhills region. These transverse dunes stand as high as 400 feet (120 meters) and extend for several miles. Their northern slopes are gentler than their southern slopes, reflecting the dominant influence of northerly winds. In other areas, dunes are more symmetric, suggesting that winds blew with nearly equal strength from the north and south, alternating with the seasons.
The grasslands that now cover the hills constitute pastureland for grazing livestock. Ranching expanded significantly in the area after passage of the Kinkaid Act in 1904, which allotted 640-acre parcels of land to ranchers who would settle it. Today, far more cattle than humans occupy the region, and half of Nebraska’s nearly 23 million acres of rangeland and pastureland are in the Sandhills. Some ranchers graze their cattle in patterns meant to approximate the large bison herds that once roamed the land.
Though much of the land in the Sandhills is privately owned, some is set aside in protected public lands. One of these areas, Crescent Lake National Wildlife Refuge on the southwestern edge of the Sandhills region, is shown above. Wetlands, including shallow lakes, marshes, and wet meadows, fill some of the valleys between the dunes. The land here is sponge-like, with …