The Mammoth Site is re-dating its bone bed to be at least 140,000 years old. This is a significant change from the previously estimated age of 26,000 years.
The discovery comes in the wake of a philosophy shift at the site. "We decided to retool what we are doing, make sure we're up to snuff and see what new technology can do," said Mammoth Site Chief Scientist, Dr. Jim Mead. The changes are all part of a three year plan to reevaluate and streamline both the site's research and educational functions.
The new date was established using optically stimulated luminescence (OSL). OSL is a dating technique which measures the time a mineral grain has gone without being exposed to light. The date was verified by multiple independent labs.
Scientists from the University of Nebraska, Lincoln, and the U.S. Geological Survey (USGS) worked alongside individuals from the Mammoth Site: Justin Wilkins, Monica Bugbee, Dr. Steve Holen, Sandy Swift and Dr. Jim Mead.
Holen was a large part of bringing the OSL technique to the Mammoth Site as he had previously worked with the USGS to date other mammoth sites.
The previous date was established with 14C dating. Since the date was originally established, scientists have learned that 14C dating can chronically underestimate the age of sites. The Mammoth Site was no exception to this and staff had expected the new technology to report an older age for the site.
"We figured it would be older, we didn't expect it was that old though," said Mead.
The new date provides a broader context for the site. 140,000 years ago, the Black Hills were in an inter-glacial period. The climate was warmer and than today. The new age may allow scientists to take a new look at climate change.
This information also allows Mammoth Site scientist to get a better understanding on why certain species were found at the site and others weren't. For example, the site has both Colombian and Woolly Mammoth remains but no Bison. Bison would have been present in the area 26,000 years ago, but may not have been 140,000 years ago. The site is also home to a shrub ox, an extinct species thought to live in warmer climates.
Part of the Mammoths Site's retooling process involves broadening research to learn about the Ice Age in the Black Hills, not just at the site. "I view the Mammoth Site as a hub," said Mead, adding that many other Ice Age remains can be found throughout the Black Hills, just not on the scale of the Mammoth Site.
The site is also is revamping it's exhibit hall. The changes are currently underway but promises to improve the educational experience for visitors learning about the Ice Age both globally and in the context of the Black Hills.
"First and foremost the Mammoth Site is an education and research facility," said Preston Gable, Mammoth Site Business Manager and COO. Gable added that the changes will only enhance accuracy of the research and learning taking place at the Mammoth Site.