For thousands of years nomadic tribes made regular trips to Big Southern Butte in Idaho (USA) to mine its deep deposits of obsidian - a black volcanic glass that forms sharp edges when broken. The tribesmen took full advantage of this phenomenon and shaped obsidian into all manner of tools and weapons.
     Through time, eastern Idaho's abundance of obsidian grew famous, and the tribes began to trade tools and weapons formed from it as something of a currency. Evidence of their activity is littered about the Idaho National Laboratory (INL) site in the form of broken obsidian flakes and, sometimes, fully formed spear and arrow tips. But just how old are the oldest artifacts that have been found in the area?
     For the past two summers, an INL archaeologist and a graduate student have been digging - literally - for answers to that question. Their excavation site is a tiered hole on the bank of the Lost River that measures about 8 feet at its deepest. "The INL site is like a treasure trove because, yeah, it's been protected by the government since the 1940s," Texas A&M student Josh Keene said. As Keene and his cohort, Clayton Marler, wrap up this year's work at the dig, Keene suspects some of the artifacts they've unearthed are as old as 10,000 years. That's an impressive number, no doubt, but they have yet to find evidence of human life that predates the so-called Clovis era.
     Archaeological orthodoxy long held that the 13,000-year-old Clovis era - named for a dig near Clovis, New Mexico - represented the earliest appearance of humans in either North or South America. That began to change when archaeologists dug up human artifacts in southern Chile that some believe predate the Clovis era. Since those discoveries, other digs thought to contain pre-Clovis artifacts have begun popping up around the Americas. Keene said the archaeological community's increasing acceptance of the theory that humans could have arrived in the Americas as early as 16,000 years ago has led some to revisit Clovis-era sites.
     At their dig on the banks of the dried-up Lost River, Keene and Marler found thousands of arrow points, animal bones and fire-cracked rocks in the first 3 to 6 feet of excavation. They then hit a layer of stones called a 'cobble layer' that contains artifacts perhaps as old as 10,000 years. They went deeper into older layers, curious of whether they'd find any evidence of pre-Clovis human life at the site. However, "The artifacts stop at the cobble layer," Keene said. "Underneath it is nothing. It's a really stark contrast."
     The fact that Keene and Marler haven't found any pre-Clovis evidence of humans at their dig hasn't dampened their enthusiasm for it. Keene said he eventually wants to return to the Intermountain West to continue with similar digs.

Edited from IdahoStatesman.com (19 September 2011)