POCATELLO, Idaho - The Idaho State University archaeological team was merely called to the scene to ensure that a planned outhouse at a new state park wouldn't encroach upon an old homestead. In the late summer of 2006, the researchers dug up pieces of an iron stove, dated 1900,a 1905 nickel and a row of buried fence posts. Curious about the forgotten ranch, they dug deeper, and they serendipitously unearthed the oldest human artifacts ever found in Idaho.
Indeed, the stone tools they extracted from the hole predate the Clovis culture of 13,000 years ago, thought until recent years to mark the advent of humans in North America.
With some of the tools estimated at nearly 16,000 years old,the treasure trove the group found at Castle Rocks State Park, part of City of Rocks National Reserve in south-central Idaho, is among the nation's oldest archaeological discoveries. For the rest of October, it's available for the public to see in a new display at the Idaho Museum of Natural History. Though the final report on the pre-Clovis stone tools is not yet complete and there hasn't been ample time to have the findings peer-reviewed, the museum opted to display them anyway to provide a talking point for the Oct. 24 Idaho Archaeological Society meeting to be hosted at ISU.
Digging at the site continued through the summer of 2007. Coral Moser, now a third-year archaeology student in ISU's master's program, was part of the team and is helping to draft the report. Moser and the others broadened their dig site after finding the remnants of the homestead. As they dug deeper into an underground Pleistocene stream, their findings became gradually more significant. First, they found the base of a white, chert arrowhead, estimated at about 500 to 600 years old.
Park Superintendent Wallace Keck offered the team the chance to finish digging the latrine in order to find more artifacts. They found the oldest specimens in an ancient, sandy stream bank about 7 feet deep. "Every level we dug down, we were finding more human-made artifacts," Moser said. "You're so excited because you know it's man-made, and the other part is, I hope I'm doing it well and taking good notes.' "You always want to make sure you're on your game just in case you find something great, you're reporting is great, too. There are a lot of neat sites out there that don't get as much credit as they deserve because the notes weren't scrupulous enough."
The Clovis culture, one of several Paleoindian groups, persisted for about 500 years. Clovis people were known for making distinct fluted points from easy-to-flake rocks. Skip Lohse, director of the Idaho Museum of Natural History and the lead member of the ISU team that made the discovery, explained the pre-Clovis stone tools he helped findlacked the distinctive flute shape. They were also made of rock types that were harder to shape, including quartzite and granite.
But it was clear to Lohse that the rocks were used as human tools from the moment he saw them. Lohse believes this discovery is one more nail in the coffin for the theory that the Clovis culture marked the arrival of humans in North America. "It's been a hot debate for the last 10 years," Lohse said. "The older sites have generally been questioned for one reason or another. In the last 10 years, more sites have come along that can't be questioned."
In this case, the team found rocks used ashammers to break flakes beside core rocks used to supply them. And the flakes were a consistent size and shape. "It has obvious flakes removed from the outside in a uniform way," Lohse said, pointing to a core rock in the display case of his new exhibit. The collection also includes a teshoa: a woman's rock knife used for scraping hide to make clothing and several woodworking tools.
"This is a big scraping tool. Under a microscope it has wear consistent with scraping wood," Lohse said, pointing to anothersparkling, quartzite rock flake. The samples have been dated by Glenn Thackray, a geosciences professor at ISU, using a relatively new process called luminescence dating.
When the mineral crystals in sediment are buried, radiation in the sediment damages the crystals. When exposed to a special light source in a laboratory, the crystals emit a faint glow, the strength of which can be used to date the age of the crystals. Thackray determined sediments taken from the layer where the tools were found were between 14,000 and 16,000 years old.
"That's in the range I predicted from the nature of the sediments in the archaeological pits," Thackray said. "Theidea that there are archaeological materials in sediment that is 14,000 to16,000 years old is amazing, frankly. When it is published, it will make a lot of people rethink the length of human history in this area."
Lohse is certain the new exhibit will capture the public's imagination, and people from throughout the country will stop at the museum to see it. "People will come from a long way away to see our artifacts," Lohse said. "It will become one of our more important collections."