Nebraska’s Mysterious Sand Dunes a Home Where Cattle Roam : Geology: The Sandhills make up one-fourth of the state. Bunch grass keeps the region from blowing away and feeds large herds of valuable livestock.

The radio goes silent as stations drop out of range.

Ghostly sand dunes with cliffs that look like the jagged end of a broken bone whip by the car’s windows.

Grit gets in the mouth, the hair, the eyes. Only bunch grass holds the sand down. There are only a few short evergreens, rolling hills, cattle, telephone wires and highway.

One-quarter of Nebraska, about 19,000 square miles, is made up of this mysterious sand, once thought uninhabitable, now a major source of the state’s cattle revenue.

It’s the largest sand dune area in the Western Hemisphere and one of the world’s largest grass-stabilized dune regions.

The Nebraska Sandhills stretch from South Dakota to North Platte and from Alliance in the Panhandle to Neligh in the east-central part of the state.

There are oases. Small lakes burst out of the Ogallala aquifer, a stretch of underground water that spreads from South Dakota and Wyoming into New Mexico and Texas.

The Niobrara, Snake, Loup and Dismal rivers cut through the land. At the edge of the Sandhills, the state’s largest reservoir--Lake McConaughy--sparkles in the sun.

Stories abound about the sand’s origins.

“I’ve heard everything from they were formed out of a giant lake . . . to they were deposited out of glaciers, out of the Ice Age,” said Jim Swinehart, research geologist at the University of Nebraska-Lincoln.

Recent studies indicate that the dunes formed out of windblown deposits from rivers that moved across Nebraska and then dried up 5,000 to 10,000 years ago, he said.

Precipitation increased and grass stabilized the dunes until about 3,500 years ago, when they dried up once again. About 1,500 years ago precipitation increased and the dunes stabilized again, with minor periods of drought, he said.

There is concern that any warming of the Earth, such as from a heightened greenhouse effect, could return central Nebraska to a desert with moving sand dunes, Swinehart said.

“Some say that in less than 50 years, we might return to dry conditions,” Swinehart said. “Pretty soon, dunes would be over the roads, blocking the rivers.”

U.S. Geological Survey crews are studying areas of the Great Plains, including the Sandhills, that are susceptible to wind erosion. Mapping and soil sampling should help scientists determine how dry it has to get before vegetation begins to die, geologist Chris Schenk said.

For now, there is just enough precipitation in the Sandhills--23 inches a year in the east to 17 inches a year in the west--to keep more than 498,000 head of cattle fed.

Figures compiled for Jan. 1 showed 1.7 million beef cows in Nebraska, fourth in the country behind Texas, Missouri and Oklahoma, said Jack Aschwege, a statistician with the Nebraska Agricultural Statistics Service.

Cash receipts for cattle and calves in Nebraska in 1988 totaled $4.4 billion--55% of the state receipts for agriculture, Aschwege said.

“The Sandhills have been over time renowned for its good cattle grazing capabilities,” said Dennis Findley of the Texas Agricultural Statistics Service.

“It’s real cowboy country, there’s no question about that,” said Charles Flowerday, co-editor of the book “The Atlas of the Sandhills.”

“It’s the kind of place where you see certain hallmarks of the late 19th Century,” Flowerday said. “Rounding up cattle on horseback, separating out calves and branding them.

“But alongside these are harbingers of the 21st Century: satellite dishes, personal computers to manage ranches, electronic marketing.”

Ranchers are largely responsible for keeping the land alive, Flowerday and others said. Measures such as controlling prairie fires and avoiding overgrazing have even improved the land, they said.

“It’s good ranching country--but you have to treat it with respect or the sand will start to roll,” said Chet Paxton, an 81-year-old rancher who lives in Thedford in the heart of the Sandhills.

Paxton’s parents moved to the area when he was 2 and soon learned farming wouldn’t work. The Paxtons now own 1,500 head of cattle on 25,000 acres of land.

“It was rough,” Paxton said of the early days. “Mother was used to Missouri and a lot of timber. She felt real bad about the barren land.”

But Paxton and others persevered.

The Sandhills weren’t always known as good ranch country. Early ranchers and farmers approached the forbidding edge and ventured no farther.