for National Geographic News
The U.S. Department of Interior has designated Nebraska's Ashfall Fossil Beds as a national natural landmark, the first such landmark to be designated in almost two decades.
The site, near the town of Neligh (see Nebraska map), is home to hundreds of skeletons of extinct rhinos, camels, three-toed horses, and other vertebrates that were killed and buried by ash from a huge volcanic eruption some 12 million years ago.
It is the only place on Earth where large numbers of fossil mammals have been found as whole, three-dimensionally preserved skeletons.
"Ashfall has tremendous value for science and education and great inspirational value," said Margi Brooks, the National Natural Landmark (NNL) Program manager, who is based in Tucson, Arizona.
"It clearly qualifies as a natural landmark."
The Ashfall Fossil Beds were uncovered in the early 1970s by Mike Voorhies, the current curator of paleontology at the University of Nebraska State Museum in Lincoln.
In 1971 he found a skull of a rhino calf protruding from an eroding ravine. The skull turned out to be part of a complete skeleton embedded in volcanic ash.
Voorhies led excavations of the site in 1978 and 1979, supported by a grant from the National Geographic Society's Committee for Research and Exploration. (National Geographic News is part of the National Geographic Society.)
About 12 million years ago, a volcano in modern-day Idaho spread a blanket of ash over large parts of what is now the midwestern United States. A layer of this powdered glass one or two feet (one- to two-thirds of a meter) thick covered the grasslands of northeastern Nebraska.
Most of the animals living in the area survived the actual ashfall, but as they continued to graze on the ash-covered grasses, their lungs began to fill with the deadly particles.
(See related news photo: "Peru Volcano Spews Deadly Ash")
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