Winter bringing Snowmass fossil dig site to a close
November 11, 2010
SNOWMASS VILLAGE – Frozen ground is expected to bring an end to the excavation of fossils at Ziegler Reservoir near Snowmass Village by this weekend, according to a Denver Museum of Nature & Science official.Kirk Johnson, vice president of research and collections and chief curator, estimated that the field team that has been working daily at the site for nearly four weeks will be gone by Sunday. Whatever prehistoric treasures the ground still holds – and there’s no reason to believe there aren’t plenty of them – will be left until spring.”Every time we dig, we find stuff,” Johnson said. The third, and possibly most complete, Ice Age bison was unearthed at the site on Tuesday. Even in the process of preparing the site to sit for the winter, more bones have turned up, he said.Light snow fell this week, but more problematic are the dropping temperatures. The ground is beginning to freeze, Johnson said. Even in the heated tent, where a crew is concentrating on removing as much of a Columbian mammoth as possible, conditions are getting difficult, he said.”It’s the freezing ground that’s the issue, really,” Johnson said. “There are plenty of things that are in the ground that you can’t find unless you dig. We’re losing our ability to dig.”Excavation of the reservoir, a project of the Snowmass Water and Sanitation District, has gone beyond what was expected to be accomplished this year in order to facilitate the recovery of prehistoric animals discovered at the site. While bulldozers push away layers of sediment, the museum’s crew of staff and volunteers watches the earth that’s overturned for signs of bones.More than 200 bone pieces have been recovered, Johnson said, but a formal tally and cataloging of what has been collected is yet to be made. This winter, scientists will map out a plan to tackle the site again in the spring, and begin the process of preserving all the bones, which must be slowly dried to prevent them from disintegrating.The push this week is to recover as much as possible of the mammoth in the tent, the first animal discovered at the site. Anything that is exposed will be exhumed, Johnson said.A jumble of bones – a section of the mammoth’s neck is lying in the middle of the pelvis – will be removed one by one. Sketches and three-dimensional images will allow scientists to re-create the jumble in the lab for further analysis, he said.Locales where scientists believe more bones exist will be buried this winter for protection. The museum is discussing ongoing security at the site, until it’s covered by deep snow, with the Snowmass Water and Sanitation District, Johnson added.Work at the site on Wednesday included continued efforts to encase in plaster and remove a 7-foot mastodon tusk and work by U.S. Geological Society paleoecologists to study the sediment layers at the site, an ancient glacial lake bed. Scientists hope to determine the age of the various layers, from which samples of mammoths, mastodons, bison, a Jefferson’s ground sloth and a small deer, among other species, have been recovered.The museum is also awaiting the results of radiocarbon dating of sediment samples, Johnson said.On Wednesday, crews also took a closer look at Tuesday’s bison find. Bones from the hind legs of the animal, along with several ribs and vertebrae, are present.Locals looking for another chance to view some of the bones discovered at the reservoir will find them Saturday from 10 a.m. to 6 p.m. in the Base Village conference center in Snowmass Village. The museum will host a free Mammoth and Snowmastodon Madness event, including an exhibit and other educational fun geared for families.