News » Mountain News

Mountain News: Snowmass-ive mud yields clues of climate change in the Rockies

Changing climate observed in the Rocky Mountains



Scientists who study prehistoric remains know they have a huge find at Snowmass, probably the biggest of their careers.

Digging furiously for 18 days last fall as winter closed in, they uncovered the remains of eight to 10 American mastodons, four Columbian mammoths and a Jefferson's ground sloth, the first ever found in Colorado and the highest elevation sample anywhere in North America.

Although a herbivore, the ground sloth was the size of a grizzly bear and "capable of ripping your face off if you got too close to it," said Kirk Johnson, chief curator at the Denver Museum of Nature and Science, at a recent press conference.

That's conjectural, as ground sloths and most other species found at the Snowmass site disappeared 10,000 years ago, soon after the last great ice sheets retreated. Other species remain, such as the camel, whose tooth was found at Snowmass. But scientists aren't sure whether the genus of the extinct Camelops, had a hump, as camels today do, or lacked one, like their modern relative the llama.

At a recent press conference in Snowmass, Johnson showed a picture of the horns of an Ice Age bison retrieved from the site. Tip to tip, the horns are close to two metres, explained Johnson, who himself stands that tall. The extinct species also stood eight and 2.6 metres at the shoulder. The bison, said Johnson, was "really the most compelling animal from this whole site."

Picking up where they left off last fall, scientist and volunteers found another 100 bones, including more mastodon remains, in just the first week of digging in May.

"These giant fossils, the skulls and pelvises each the size of a car door, are in one large one bed among massive shoulders," explained Johnson. "We are just baffled as to why they are all in one place."

As captivating as these bones are, the more interesting story yielded by the muck at Snowmass may be of changing climates in the Rocky Mountains. Adding relevance is the location, elevation 2,700 metres. It is, said Johnson, "the best high-elevation site in North America."

Johnson and other scientists have a long way to go. Even after digging ends on July 1, they have probably two years of work ahead as they take the many discoveries to create a broad picture of life and change over what may have been a 100,000-year period.

At the start of digging this spring, 16 tusks had been uncovered, so well preserved that the annual growth rings could be studied, testifying not only to the age of the animals but even to the season of death. "These really start to tell the story," said Johnson.