Museum Concludes Ice Age Fossil Excavation

The Denver Museum of Nature & Science has completed its largest-ever fossil excavation project 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.  Below is a summary of activities related to the seven-week endeavor, which yielded a treasure trove of Ice Age fossils.


In total, 4,826 bones were pulled from the site in 2011, including

  • 74 large specimens in plaster jackets
  • 49 tusks (29 upper jaw tusks and 20 lower jaw tusks)
  • 34 mandibles (jaws)
  • 23 skulls
  • 20 pelvises
  • 82 loose teeth

Additionally, crews recovered

  • 125 logs and numerous samples of peat, wood, leaves, and rocks

26 different vertebrate animals from the site have been identified, and the number of Ice Age species will grow as work continues at the Museum.

7 large mammals:

  • American mastodon, parts of at least 30 individuals; most prevalent large animal at the site
  • giant bison, parts of at least 10 individuals
  • ground sloth, parts of at least 4 individuals
  • Columbian mammoth, parts of at least 3 individuals
  • deer, parts of at least 3 individuals
  • horse, based on a single ankle bone
  • camel, based on a single tooth

19 types of smaller animals:

  • otter
  • muskrat
  • vole
  • mink or weasel
  • chipmunk
  • bat
  • rabbit
  • beaver, known from distinctly chewed sticks
  • mouse
  • salamander
  • frog, 4 species
  • lizard, 2 species
  • snake
  • fish
  • bird, numerous species


15 local educators from the Roaring Fork Valley worked side-by-side with renowned scientists and other Museum staff doing the actual work of the excavation. The volunteer program aimed to give educators real‐world experience with the science happening right in their own backyard so they can inspire their students and neighbors with their knowledge and personal experiences from working on the fossil dig.

6 students from Colorado Mountain College also participated by excavating fossils using shovels, pick axes, trowels, and brushes; screening sediments to look for bone fragments and other material; applying plaster "jackets" to fossils in the field; and washing and cataloging fossils.


55 scientists were onsite to begin intense scientific investigation about the origin of the Ice Age lake and its history. This included most of the scientific team of 37 experts from 18 institutions in the United States, Canada, Spain, and England, who are involved in the project and whose work will make the most of the site's scientific potential, as well as several other affiliated scientists.

Their onsite activities included collecting cores of sediment from the ancient lake bed totaling 56 meters in length, studying the sediment that fills the ancient lake, making high-resolution scans of the fossils in place, and collecting more than 1,100 samples for analysis.


6,000 local elementary students (grades preK-6) experienced "Time Scene Investigation: Snowmass Village," a tech‐savvy assembly program developed and delivered by the Museum. This interactive program allowed students to learn more about the Ice Age fossil discoveries through top‐notch professional science educators, specimens from the Museum collections, props, and multimedia presentations.

400 local middle and high school students experienced "Mammoth of a Find: Live Broadcast from the Dig Site."This 45‐minute live broadcast connected Museum scientists from the Ice Age fossil dig site directly with students via satellite for a two‐way interactive experience. Scientists shared new discoveries, demonstrated field research techniques, and answered questions to give students a window into science careers.

1,600 people attended the Ice Age Spectacular in Snowmass Village. The two-day event, hosted by the Museum in partnership with Snowmass Tourism, allowed participants to see real fossils discovered less than a mile away; watch live broadcasts of Museum scientists at the dig site; play Ice Age games, puzzles, and crafts; meet Snowy the mascot; and enjoy activities for the whole family.


At the site: Construction on Ziegler Reservoir resumes as planned this week and Museum representatives will remain onsite throughout the summer to monitor the site and recover any additional fossils that are uncovered while construction crews excavate clay to build the dam.

At the Museum: After fossils are removed from the ground, they are placed in a process chain designed to maximize their preservation. Due to the moisture content of the bones, which were buried in wet silt and peat for tens of thousands of years, the bones are very fragile and will disintegrate if allowed to dry out too fast. It can take many months for the fossils to properly dry. Some of the fossil bones required a plaster of paris jacket to remove them from the ground and protect them during transport to Denver. In the Museum fossil preparation lab, the jackets are removed, the fossils are cleaned, and the slow drying process begins.


Long-term plans have not been finalized. The Museum is still in the very early stages of analyzing the fossils and has yet to create a long-term plan. The Town of Snowmass Village Ice Age Discovery Committee, the "Tusk Force," is building a separate long‐term strategic plan to capitalize on the educational and economic development opportunities this discovery offers to the Town of Snowmass Village and the Roaring Fork Valley.

Project Updates

Get caught up on everything that happened in the field, learn what scientists are doing to preserve the bones, and find out the latest discoveries from our team of experts.

Learn more

Discovery Timeline

See how this amazing discovery unfolded, from the first fossil to the last day of the dig.


Digging Snowmastodon

Order Digging Snowmastodon: Discovering an Ice Age World in the Colorado Rockies, a first-person account of the historic Ice Age fossil find, today!

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