Science Updates and Landscape Paintings of the Dig Site

In July 2011, the Denver Museum of Nature & Science completed its largest-ever fossil excavation at Ziegler Reservoir near Snowmass Village. The preserved series of Ice Age fossil ecosystems is one of the most significant fossil discoveries ever made in Colorado. Over the past four months, work on the Snowmastodon Project™ has gone on behind-the-scenes as the Museum continued to preserve and curate the fossils, launched a thorough scientific analysis of the site and commissioned a series of paintings that show the site during various time periods.


A team of international scientists has been hard at work over the past several months to begin analysis of this historic discovery.

"We are in the early stages of scientific study and plan to continue offering updates on our progress," said Dr. Kirk Johnson, vice president of the Research and Collections Division at the Museum. "There are now more than 40 scientists investigating various aspects of the site and new data is pouring in daily."

Individuals from the Snowmastodon Project™ science team revealed the following new information at two recent national science conferences:

  • Growing Animal Species Count-Now 41: The list of different species from the site continues to grow. In addition to seven large mammal species-mammoth, mastodon, Jefferson's ground sloth, camel, deer, horse, and giant bison-the site has yielded an additional 34 species, including trout, salamanders, shrews, bats, weasels, river otters, rabbits, frogs (4 species), snakes (2 species), lizards (2 species), birds (5 species), and rodents (14 species, including beavers, muskrats, voles, lemmings, mice, gophers, chipmunks, and ground squirrels).
  • Mastodon Entrapment Theory: Scientists are testing a hypothesis that the more than 30 mastodons uncovered at the site were trapped there in lake sediments that transformed into quicksand during an earthquake or series of quakes.

"Evidence such as the nature of the debris flow deposits, the condition of the bones, and the distribution of the bones may support this scenario," said Johnson.  "Ultimately we use many types of data to test more than one hypothesis.  This site is really complicated and this work is just beginning."


World-renowned painter and muralist Jan Vriesen has completed a series of five paintings of the Ziegler Reservoir landscape. The paintings are acrylic on canvas, each measures 38" by 57", and they represent five different times:

  • About 130,000 years ago, after the formation of the lake basin by a glacier that spilled out of Snowmass Creek Valley
  • About 120,000 years ago, when the area was dominated by mastodon, giant ground sloths, and bison
  • 60,000 to 45,000 years ago, when the area was dominated by mammoth, camels, and deer
  • November 15, 2011, as the first phase of fossil excavation was concluding
  • Summer 2012, after the dam was completed and Ziegler Reservoir was filled

"Jan was at the site in November and June and we worked together so he could create these amazing landscape paintings that integrate geology, paleobotany, and vertebrate paleontology," said Johnson.  "These visual representations are important tools in helping us show how this site evolved over time.  All of the paintings are made from the same vantage point, from the north side of the lake looking south with the Snowmass ski area visible to the left and the Snowmass Creek Valley and Mount Daly visible to the right."

Project Updates

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Discovery Timeline

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Digging Snowmastodon

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