One morning last July, as Colorado Gov. John Hickenlooper looked on,
 scientists supervised the hoisting of a 10,000-pound cast of a Columbia 
mammoth skeleton -- rocks included -- onto a flatbed truck for shipment to the Denver Museum of Nature & Science.

After 60 days of intense digging, the scientists and scores of volunteers
 attracted by the dig near Snowmass Village, Colo., had uncovered nearly
 5,000 bones of all manner of Ice Age species: the tooth of a camel, a bison half as big again as the ones we know today, and the claw of a Jefferson's ground-sloth, a plant-eating animal about the size of today's grizzly bears. The treasure trove was mind-boggling.

The mammoth bones uncovered Oct. 14, 2010, triggered the excitement of what came to be called the "Snowmastodon." Jesse Steele, the bulldozer operator who unearthed the bones from the mud, and project superintendent Kent Olson studied the bones that night, sleuthing the Internet before concluding they'd found a now-extinct species. The next morning, they alerted officials from the water and sanitation district who'd hired them to scoop out the Ziegler Reservoir site. Work was suspended as paleontologists gleefully plucked bone after bone from the pit for 18 days last November, returning last May for six more weeks of mucking.

Working with shovels and aided by the powerful teeth and jaws of the heavy equipment, the scientists probed deeper into the ancient lake deposits, turning up the remains of at least 30 mastodons. Like mammoths, now-extinct relatives of today's elephant, mastodons stood slightly shorter, 11 feet at the shoulder, and had teeth adapted for browsing trees, not munching on grasses. There were dozens of tusks, each with the growth rings that amounted to a Day-Timer's record of that individual's life.

Never in the world have mastodon bones of such quality and quantity, and with such diversity of ages, been found. Even more surprising was the fact that they were found at an elevation of nearly 9,000 feet, said Dr. Kirk Johnson, chief curator at the Denver Museum. "We think it's one of the finest mastodon sites in the world," said Johnson.

How did the mastodons get there? One hypothesis being tested by the 40 scientists studying the find has the animals loitering in the lake one day when an earthquake hit, liquefying the lake sediments into a quicksand from which the beasts could not escape. Slowly, they starved, and then more quakes occurred, causing their bones to descend to the lake's depths. Some bones and theories will be displayed in the ski resort town of Snowmass Village, where town officials hope to boost the non-skiing economy with the allure of the ancient. Learning can be fun -- and perhaps lucrative.

The most interesting detective work focuses less on the giant beasts than on the seeds, pollens and other detritus of the dig. That research aims to help us understand what the climates were like in the last extended period between giant glaciers, and perhaps give us a sense of those changes.

That period of roughly 50,000 to 150,000 years ago was much like our own, scientists think, though herds of elephant-type creatures no longer tromp around the Rockies, and the world back then never experienced squadrons of SUVS, giant smokestacks at coal-fired power plants or other ubiquitous aspects of modern life. That is why the dig at Snowmass may transcend being a curious sideshow about the past and become part of an important yardstick for climate change.

We already have some evidence about natural climate changes. Ice cores from Greenland and Antarctica contain scores of telltale signs from which climates of the past can be inferred. But the heightened sensitivity of higher elevations to climatic shifts has its own value. The giant bones of the mammoths and mastodons that grazed and browsed just a quarter-mile from today's ski lifts may be astonishing, but the big news during the next several years may come from these microscopic proxies of climates past.

If this site does yield important clues about "natural" climate change, that will be an irony. Creation of the reservoir was prompted, in part, by
 concerns about the shifting climate in the Southwest, a fear that even
 communities at the base of ski slopes in Colorado may not be immune to
 tightened water supplies.

As for the bones, more of them undoubtedly lie below the reservoir waters. Paleontologists aren't concerned. The same layer of clay that created what the Denver Museum's curator calls a giant Tupperware lid remains over the ancient lakebed. Armed with new insights and techniques, scientists can return someday and pop the seal of Snowmastodon to see what other treasures lie beneath.

Allen Best is a contributor to Writers on the Range, a service of High
Country News (hcn.org). He lives in Denver and publishes the newsmagazine, Mountain Town News.