Obsidian was valued by ancient cultures for its sharpness and durability. Archaeologists commonly find obsidian nodules or worked obsidian in the form of points, knife blades, etc., in archaeological sites throughout the Western Hemisphere and beyond. Because of the particular way obsidian is formed, each source of obsidian has a unique geochemical signature. Thus researchers can identify where the obsidian that was used to make a particular artifact originally came from. The source provides clues about how the humans who made the artifacts interacted with other groups, either via trade or migration. In our own region, artifacts and raw material originating from the obsidian deposits at Mule Creek, New Mexico, have been found at archaeological sites up to 120 miles away.
Recent news has revealed that some ancient humans carried obsidian much further. A team of underwater archaeologists from the University of Michigan recovered two flakes of obsidian from the bottom of Lake Huron under 100 feet of water. The scientists were working along the Alpena-Amberley Ridge, an underwater geologic formation that connects Michigan to Ontario, which more than 10,000 years ago had once been a ridge of dry land flanked by water on each side. The obsidian flakes bore the telltale signs of human modification (knapping). Once the archaeologists tested the obsidian samples, they discovered that the source of the obsidian was in central Oregon, some 2500 miles away. This suggested to the scientists that there may have been a more extensive and more long-lasting network of trade, exchange, or even migration across the North American continent than had been previously assumed.
For details, and to enjoy a 4-minute video about this discovery, click here.
/s/ webmaster [top photo, M.Smith; bottom photo via Scientific American]