Sculptor Bill Ikler was hiking along the edge of a snowfield near the Continental Divide when a friend picked up a cracked, waterlogged, gray-brown chunk of what looked like driftwood.

"We were probably 3 or 4 feet away from a snowfield, and my friend Janet picked up something and asked if it was wood or if it was bone," Ikler recalled.

Ikler, who had once studied a bison skull while doing research for one of his sculptures, recognized the 8-inch-long object immediately: It was the bone core from a bison horn.

"And then I looked down, and right near my hand was the other core, the other bison horn," he said, recalling the late-summer 2002 hike west of Nederland. "These had just melted out of the snowfield. They were literally pulled from the muck."

Samples were sent to the Lawrence Livermore National Laboratory for radiocarbon dating, and the results were surprising.

The bison-horn cores were 2,090 years old, said University of Colorado archaeologist Craig Lee.

In September 2002, a hunter found another ancient bison horn in the high country south of Rocky Mountain National Park. Once again, the remains were found melting from a perennial snowfield depleted by the multiyear drought.

But this specimen was a bison-horn sheath - the glossy, black exterior part of the horn. Horn sheath is made of keratin, the same fibrous protein found in fingernails.

"It's tough stuff, but it's very much weaker than bone," Lee said. "Once exposed to the elements, it would disintegrate within 10 years, easily, and probably a lot less."

Samples were sent for dating. And once again, the results jolted scientists: The horn sheath was 2,280 years old, Lee said.

In recent years, deer, elk, bighorn sheep and bison remains have been recovered from melting glaciers and snowfields in the Colorado high country. Some were a few centuries old, but none came close to the age of those bison horns recovered in 2002.

To Lee, the discoveries indicate that ice along the Continental Divide has retreated to levels unseen since the time of Christ.

"Skull fragments would not be able to sit out on the surface, unprotected, for two millennia," said Lee, a doctoral candidate in the CU anthropology department.

"They had been protected by the snow and ice for 2,000 years, and now they're melting out," he said.

Around the world, retreating mountain glaciers are creating a windfall for researchers such as Lee and his faculty adviser, CU archaeologist James Dixon. Lee and Dixon spend part of their summers scouring the fringes of retreating Alaskan glaciers, looking for ancient artifacts.

When they return to Colorado at summer's end, Lee heads to the high country to walk the edges of glaciers and snowfields.

What he'd really like to find is evidence - stone projectile points, for example - tying prehistoric hunters to big-game animals that ended up in the snowfields.

Prehistoric game drives and hunting blinds have previously been documented in the high country west of Boulder.

"At this point, we can't say that human beings had anything to do with these bison winding up in the snow and ice patches," he said. "But I think there might be a chance that prehistoric artifacts might be up in those patches, too."

While the discovery of 2,000-year-old bison horns leaves Lee wondering about the past, the find makes Ikler ponder the future of the Front Range.

Ikler, 56, has been hiking along the Continental Divide since the early 1970s.

"These things were very, very old," he said. "So this is a warning that these snowfields are melting fast. It just reinforces my feeling that we need to do something about global warming."

Glacial artifacts

• Bone cores from ancient bison horns: The horn cores are about 8 inches long, found melting from a snowfield by hikers near the Continental Divide west of Nederland in late summer 2002. They were radiocarbon-dated at 2,090 years old.

• Bison horn sheath: The glossy, black exterior part of a horn, the horn sheath is made of keratin, the same fibrous protein found in fingernails. A hunter found it in the high country south of Rocky Mountain National Park in September 2002. It was radiocarbon-dated at 2,280 years old.

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