GARDNERVILLE - More than 2,000 acres of public land near Ruhenstroth was closed to off-road vehicles Tuesday to protect fossils from erosion.
The site, located one-half mile from the east Carson Valley community, covers 2,340 acres in the Pine Nut Mountains.
The closure affects only vehicle traffic, not horseback riders or walkers, according to Chuck Pope, the Bureau of Land Management's assistant field manager for non-renewable resources.
Pope said there are a number of fossil sites in the area just south of Fish Spring Road.
"There are fossil remains, including jaws, bones, teeth, the sort of thing usually deposited in a flood plain," Pope said. "This is not just the mastodon, there are many other vertebrate resources in the area."
Pope said the closure to off-highway vehicle use is immediate and that signs will go up along roads entering the area in the near future.
"There is a road coming through this parcel that will remain open," he said. "So there will still be access to public lands through the parcel."
The emergency closure is designed to prevent off-highway vehicles from riding drainages where they might damage or uncover fossil remains, where they might be destroyed or illegally collected.
Pope said the area has been nominated as the Ruhenstroth Paleontological Area of Critical Environmental Concern in the Pine Nut Resource Management Plan. A draft of the plan will be ready for public review later this year.
Dr. Harold Schorn, a University of California, Berkeley paleontologist, conducted a study of the area.
"There are still areas open to ride off-highway vehicles outside of the area," Pope said. "The main thing is to protect the resources inside the boundaries of the area."
The closure area straddles Pinenut Road just east of the Douglas County Fairgrounds. Pope said the road will remain open.
It was an 18-year-old motorcycle rider who found mastodon bones in the Pine Nuts four years ago.
Derek Prosser was riding his motorcycle when he found the 3 million-year-old fossil bones.
The Pine Nuts were wetter and warmer with lakes and small streams when the mastodon roamed Ruhenstroth.
Contact Kurt Hildebrand at hildebrand@nevadaappeal.com or 881-1215.
