Snowmass fossils may come from ancient lake | AspenTimes.com

Snowmass fossils may come from ancient lake

Janet Urquhart
The Aspen Times
Aspen, CO Colorado

Janet Urquhart The Aspen Times

SNOWMASS VILLAGE – The Denver Museum of Nature and Science will next week begin excavation of a fossil site near Snowmass Village where the remains of several prehistoric animals have been discovered, after finalizing the details of an agreement with the Snowmass Water and Sanitation District on Friday.

Evidence of more than one mammoth, along with a mastodon tooth, have been unearthed at Ziegler Reservoir, just west of town. The bones will be donated to the museum, which will create a cast model of one of the mammoths for display in Snowmass Village – a process that could take as long as two years.

Dr. Steve Holen, curator of archeology and the museum’s resident mammoth expert, visited the site Wednesday, went back to Denver, and returned Friday for an extended stay. A team is being assembled to exhume the remains of large animals that experts believe walked the earth toward the end of the last ice age, about 12,000 to 16,000 years ago.

The site is shaping up as a possible treasure trove of fossils since a bulldozer first unearthed the bones of a mammoth on Oct. 14. The initial discovery site is enclosed in a chainlink fence and covered by a heated tent. It is an island in a sea of goo. Work this week beyond the perimeter of the original discovery zone revealed additional, large tusks and a mastodon tooth in the mud.

Holen will spend the weekend working on a strategy to expose whatever else might exist at the site. Sifting through dirt, a typical method of exposing finds in an archeological dig, may not work at the soggy reservoir, he conceded.

The first mammoth was found in a deep layer of damp peat, sandwiched between silt below it and clay above it. The encased layer preserved the bones without allowing them fossilize – turn to stone, in other words – though the bones are considered fossils because they are more than 10,000 years old.

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“I was amazed by the peat bed here. That’s incredible for this part of the world,” Holen said.

The dig is not like any site Holen has worked before, he said, but he hypothesized that the area was at one time a glacial lake that attracted the wildlife of that time period.

“It would have been a watering hole for the mammoths and mastodons and other animals that lived in this landscape,” he said. “Obviously, some of them died here.”

If the lake was in existence for thousands of years, it would make sense that the remains of various animals exist at the site, Holen added.

Not including the Snowmass finds, 103 discoveries of mammoth bones and three mastodons have been recorded in Colorado. The discovery of just one bone would count in that tally, Holen said.

What’s unusual about the Snowmass site is its elevation – 8,960 feet. The juvenile mammoth uncovered by the bulldozer operator on Oct. 14 appears to be the most complete mammoth fossil found at high elevation in Colorado, according to the museum. Roughly 25 percent of that animal’s bones have been recovered so far. It was a Columbian mammoth, Holen said. He has seen no evidence, at least not yet, of a woolly mammoth at the site.

The district continues to display both the bones of the mammoth that was found first, and some of the more recent discoveries, including the mastodon tooth. They will be on display Saturday and Sunday from 9 a.m. to 4 p.m. at the district office, located behind the Snowmass Club, at 0177 Clubhouse Drive.

Scientists will be studying not only the bones, but the peat, which they hope will yield clues about the environment in which the animals lived. One of Holen’s first goals is to collect samples of peat for radiocarbon dating, which will help pinpoint the time period in which the animals died, he said.

Radiocarbon dating of the bones themselves and efforts to extract DNA from the fossils will also be done, according to the museum.

Scientists will also be looking for evidence of humans at the site.

“I don’t know if there’s a human association here,” Holen said. “That’s one of the things I hope to learn.”

Under the terms of the agreement between the district and the museum, the museum will take on the responsibility for preservation of the fossils. The bones are wet; if they dry too quickly they will crack and disintegrate, according to Holen, who praised the Water and Sanitation District for its care of the site and the bones since the initial discovery.

Once the archeological dig begins in earnest next week, the museum has said it will provide regular updates on the progress of the operation at http://www.dmns.org. It has also agreed to allow school groups to visit the excavation site during the work, as conditions permit.

janet@aspentimes.com