22 March 2015
Prehistoric stone tool site discovered in suburban Seattle
Archaeologists surveying the waterways of suburban Seattle (Washington, USA) have discovered an ancient tool-making site dating back more than 10,000 years. The find includes thousands of stone flakes, an array of bifaces, scrapers, and hammerstones, plus several projectile points.
The site was discovered along a creek in Redmond, Washington, under a layer of peat that was radiocarbon dated to about 10,000 years ago. And in the layer with the artifacts were burned bits of willow, poplar, and pine, which were themselves dated between 10,000 and 12,500 years ago. Together, these materials frame a period of prehistory in coastal Washington which archaeologists have not been able to explore before.
"It's the oldest artifact assemblage from western Washington, and the excellent context in which we were able to do our excavations and sampling is now providing a picture, much clearer than ever before, of the environment these people were living in during the transition out of the Ice Age," said Dr. Robert Kopperl, lead researcher of the find.
Kopperl, from the firm SWCA Environmental Consultants, and his colleagues first made the find in 2008 while surveying a waterway known as Bear Creek. Initial work turned up some stone artifacts above the layer of peat, which was carbon dated between 8,000 and 10,000 years old. "when we did our 2009 test excavations, all of the artifacts we found were below that peat instead of above the peat, indicating that they pre-dated 10,000 years before the present," saud Kopperl.
Once they picked up traces of human habitation older than any other found in the region, the researchers hoped to encounter artifacts that had never been found there before. "We found two projectile point fragments that were concave-based - something not seen at any time in the local projectile point sequence," said Kopperl.
In all, six projectile points and base fragments were found at Bear Creek. The two points with concave bases somewhat resembled Clovis points, which have been found elsewhere in the region but without clear archaeological contexts, Kopperl said. But rather conspicuously, both newfound artifacts lacked the distinctive fluting that's typical of the Clovis style. Meanwhile, he added, a third point fragment was 'reminiscent' of a style known as the Western Stemmed Tradition, which is typically found farther inland.
As for the lifeways of the people who made and used these tools ten millennia ago, the clues are scant. Residue analysis of several fragments, for instance, turned up traces of plants like beeweed, and proteins from bear, bison, deer, sheep, and salmon. Beyond that, there's not much context to draw on in western Washington, Kopperl said, because no other artifacts have been found that date this far back in time.
"There are probably other Late Pleistocene-Holocene sites preserved in similar modern settings in the Lowlands, and we should be on the lookout for them. Also, this is confirmation that these kinds of sites do actually still survive in a rapidly developing place such as suburban Seattle," Kopperl concluded.
Edited from Western Digs (18 March 2015)