The Obsidian Trade in North America

At http://geology.com/press-release/obsidian-artifacts/ is a story with some potential for the future (and like the previous story is also available at Science Daily). Obsidian, or volcanic glass, was prized for making tools, and an archaeologist in Idaho has plotted and catalogued obsidian pieces from his patch as he has devised a clever way of using them to shine a little window on the habits of Native Americans over the last 13,000 years. As each volcano has its own unique chemical signature (in the obsidian) he has been able to trace each piece to its geological source – as far afield as Californian and Nebraska. In other words, he has produced a virtual map of old trade and migration routes.