Dr. Kirk Johnson, recently appointed as director of the National Museum of Natural History, speaks about the mastodon dig and other findings in the Ziegler Reservoir, at the Mountain-Plains Museums Association opening session at the Wheeler on Tuesday morning.
Dr. Kirk Johnson, recently appointed as director of the National Museum of Natural History, speaks about the mastodon dig and other findings in the Ziegler Reservoir, at the Mountain-Plains Museums Association opening session at the Wheeler on Tuesday morning. Credit: Jordan Curet / Aspen Daily News

ASPEN – New information about climate change will be published later this month in the first comprehensive paper detailing the “exquisite finds” at Ziegler Reservoir that were discovered in 2010-11.

Thousands of bones and myriad plant matter covering a 60,000-year span of time have provided scientists with reams of valuable data about climate at high altitude during the ice age, according to Dr. Kirk Johnson, former chief curator with the Denver Museum of Nature and Science.

Speaking Tuesday at the keynote address for the Mountain-Plains Museum Association conference that continues through Oct. 2, Johnson, now the director of the Smithsonian Institution’s National Museum of Natural History, called it “A most phenomenal site about what it tells us about climate.”

Just 12 acres in size, the Snowmass discovery area is unique on this continent because it’s located above 8,000 feet in elevation. Johnson called it both “The best high elevation site in the world” and “the best ice age site of any kind in North America for diversity.”

Following the initial discovery of a large animal’s skeleton by bulldozer operator Jesse Steele on Oct. 14, 2010, “This amazing site began to reveal itself,” Johnson recalled. After just two weeks of digging, volunteer crews had unearthed 28 piles of bones.

“You couldn’t go anywhere without running over a mammoth or a mastodon,” Johnson said to peals of laughter by the Wheeler Opera House audience. “We started calling these things ‘Flintstone moments.’”

The site produced one large bone per cubic meter and at its peak, nearly 300 bones were discovered in a single day.

Fifty mastodons, 12 mammoth, a half-dozen Jefferson sloth and an ice age deer have been identified while more than 26,400 small bones are believed to have come from salamanders, beavers, otters, rabbits and snakes. Close to 70 tusks are being used as markers of time, not unlike tree rings.

“There’s so much data that came out of there,” Johnson reiterated, noting that a decade’s worth of information could still be extrapolated.

Chief among the unanswered questions remains a puzzling find of a huge male mammoth surrounded by large rocks in the middle of the lake. “That’s what a meat cache looks like,” Johnson said.

Heretofore there’s been no physical evidence of human inhabitation on this continent as early as 70,000 years ago, but the question of how these rocks came to be arranged in such a manner remains one of the reservoir’s mysteries.

On multiple occasions during his talk, Johnson took umbrage at a quote and headline in the Sept. 29 Aspen Daily News suggesting the discovery project was moving, locally, at a “glacial pace.” The museum head noted, “every part of this thing has been super fast” including the speed at which local decisions have been made about the find.

Unique ancient lake site

The pristine condition of pollen, bugs and even a huge tree pulled from the reservoir is key to helping scientists “fill in the climate picture locally,” Johnson said. “A local spot point is always going to be different from a global average.”

While the initial finds took place nearly four years ago, property owner Doug Ziegler recognized something special about the area back in 1958, when it was just a meadow. Ziegler paid for its excavation but the small lake never amounted to much as a trout fishing pond. A subsequent study deduced that this was likely the site of an ancient lake as it was surrounded by a ring of hills and had no steams feeding into it.

The Snowmass Water & Sanitation District purchased water rights for the reservoir in 2010 to bolster the community’s anticipated future needs. Shortly after the lake was drained came the discovery of a skeleton that elicited this response from a Water & San representative: “You know, that’s not a cow,” Johnson recalled.

In fact, it was a young Columbian female mammoth. In short order, tusks and leg bones were found.

Winter weather brought an end to the first excavation period and Johnson and his colleagues returned to Denver. There, they planned for a spring return to the site.

He contacted 44 scientists, “a scientific dream team” all of who said they wanted to work on the project.

During the winter closure, Johnson also raised $1 million for the project that spanned May 15-July 1, 2011 and involved 200 volunteer “diggers,” including many local teachers.

Chris Faison, who teaches at the Aspen Community School, was credited with finding the head of a ground sloth who had been nicknamed “Ziggy.” Johnson said that was one of his highlights of the entire experience.

Some 6,000 cubic yards of dirt was moved in 50 working days but that only represented about 10 percent of the entire reservoir. There’s no real rush in reopening the site in the near future, Johnson said, because of the volume of information that has to be studied.

“There are still fossils in the rest of the lake that lie waiting to be dug up,” Johnson said. “You could go back in and take another bite out of that pie.”

A gravel road has been constructed at the bottom of Ziegler Reservoir in anticipation of the next team of explorers and scientists willing to dive into this unique ice age find.

Editor’s note: Aspen Journalism and Aspen Daily News collaborated on this story. The Daily News published the story on Wednesday, Oct. 1, 2014.