Fossil hunters return to Snowmass |

Fossil hunters return to Snowmass

Janet UrquhartThe Aspen TimesAspen CO Colorado
Ann Larson Snowmass Sun

SNOWMASS VILLAGE – Armed with shovels, rubber boots and the anticipation of discoveries about to unfold, a crew of scientists will return to Ziegler Reservoir near Snowmass Village Sunday to resume their hunt for Ice Age fossils.The Denver Museum of Nature & Science has seven weeks to recover whatever treasures it can from the stunning cache of prehistoric remains that first came to light late last fall, when a surprised bulldozer operator unearthed the bones of a Columbian mammoth. Six large SUVs, their back seats removed to make room for gear, will hit the road from Denver on Saturday, as will a crew of 25 to 30 fossil hunters. They’ll come prepared for mud, as well as a more methodical approach to the excavation than occurred last year, when they labored alongside big machinery at work on enlarging the reservoir.”Last year, we were working in the same hole. It was a little more of a salvage operation,” said Dr. Ian Miller, the museum’s curator of paleontology.This time, there will be one backhoe, employed by the museum, to move the muck out of the way after it has been combed for fossils. A small crew working on expansion of the reservoir will also be on hand, but off to the side of the fossil dig, not in it.”We’ll have 30 people shoveling all the time,” Miller predicted. “It’s going to be a little bit different than last year.”Scientists and trained volunteers managed to collect some 600 bones and bone pieces last fall, including 15 tusks. Over a two-week period, they uncovered a bumper crop of plant and animal specimens, including parts of eight to 10 American mastodons, four Columbian mammoths, two Ice Age deer, four Ice Age bison and one Jefferson’s ground sloth (the first ever found in Colorado).The dig crew, with people rotating in and out each week, will swell to 35 to 45 people by the middle of next week. As many as 70 people at a time could be plying the reservoir before the intensive search wraps up July 1. In all, 36 scientists from 15 institutions and four countries will help analyze the Ice Age ecosystem preserved in the reservoir sediment, Miller said.There will, for example, be a fossil pollen expert who takes sediment samples at every five centimeters of depth. A sample the size of a sugar cube can contain 10,000 grains of pollen, according to Miller.”It really gives us a picture of that whole ecosystem,” he said.A much larger core sample – a couple of hundred pounds of sediment – will be screened to search for evidence of microvertebrates – things like mice teeth and the vertebrae of tiny fish.Scientists believe Ziegler Reservoir dates from 150,000 years old at its deepest layers, to about 50,000 years at the shallowest layers – a 100,000-year snapshot of the Ice Age as an ancient lake slowly filled in.Because carbon dating can only date material out to about 45,000 years, other methods will be employed this year to date the various levels of the site – tongue-twisting techniques such as optically stimulated luminescence and cosmogenic exposure dating.”All these scientists are coming to get that work done,” Miller said.Their conclusions, however, may be months, or even years in the making.A skeleton museum crew will remain at Ziegler when dam construction begins, July 2, just in case, but with the newly enlarged reservoir expected to be filled with water sometime this fall, the next seven weeks will be crucial to recovering whatever secrets the site might yet yield.The Denver museum is the repository for the specimens collected at Ziegler, and its paleo lab has been busy all winter preserving and cataloging last year’s finds. The lab will be closed during this year’s dig, though, as most of its staff will be in and out of the Snowmass site.Most of the fossils found last fall have been carefully dried; some are still in that process, according to Miller. The horns and skull of an Ice Age bison have been assembled for display in the lab window. “It’s just stunning,” Miller said.The young, female mammoth dubbed Snowy, the first find at Ziegler, was lifted out of the earth en masse last fall, bone and sediment together, as winter closed in. That fossil, each piece now cataloged, is about 60 to 70 percent complete, and this year’s dig will include efforts to find more of her remains, Miller said.One of the deer fossils found last fall is 90 percent complete – a rarity in paleontology, according to Miller.”That is such a stunning specimen,” he said.The museum will create a cast of one of the fossils and turn it over to the Snowmass Water and Sanitation District, owner of the reservoir, for display. Community focus has been on a cast of Snowy, but it could just as easily be the deer, if that’s what is requested, Miller said.At some point, long after Ziegler is again a reservoir, an extensive exhibit of the fossils is probable, though it may not be a permanent feature of the museum, he said.”We want to share them more than anybody,” Miller said. “I want people to see this stuff.”

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