American underwater archaeologists found at the bottom of Lake Guron unique stone artifacts nine thousand years old. The tools were made of obsidian mined in a quarry in Central Oregon, located approximately four thousand kilometers from the site of the discovery. This is inconsistent with the established pattern of distribution of obsidian artifacts in pre-Columbian America. The study, published in the journal PLOS ONE, is summarized in a press release on Phys.org.
Researchers studied submerged areas of topography that were previously inhabited by plants, animals and humans 8,000 to 10,000 years ago and are now at the bottom of Lake Guron, one of the Great Lakes of the United States and Canada. To archaeologists, this paleolandscape represents an intact “record” of the late Pleistocene and early Holocene environment, including ancient human camps. At a depth of 32 meters, between two hunting structures, archaeologists found two obsidian splinters.
Among primitive people, obsidian was considered a valuable raw material because of its ability to split into fragments with cutting edges and its aesthetic qualities suitable for making jewelry. The volcanic mineral has been widely used and traded throughout much of human history, and the unique chemical signatures of stones from various deposits allow archaeologists to trace ancient trade relations and social connections in such regions as the Arctic, Eastern Mediterranean, Southeast Asia and Mexico.
In the United States and Canada the sources of obsidian are quarries in the northwestern United States – in the Rocky Mountains and east of them (as far as South Dakota) and in the southwestern states of Arizona and New Mexico. Interestingly, the archaeological finds of obsidian artifacts east of the Rocky Mountains follow a clear chronological pattern. They were systematically used as an exotic commodity by ancient Indians in the mid-Woodland period (from 1000 B.C. to 1000 A.D.), but earlier finds were sporadic and represented by only a small number of obsidian splinters. They usually came from eastern sources in Wyoming and New Mexico.
Given this pattern, the discovery of two ten-thousand-year-old obsidian flakes at the bottom of Lake Guron is unprecedented. Their source is a quarry not east of the Rocky Mountains, but in the west, in Oregon, some four thousand miles away, making the find the oldest evidence of western obsidian in the continental United States.
According to scientists, both specimens arrived from Oregon to the Great Lakes region via a chain of hands, rather than direct access to an obsidian source. This means that there was already at that time a developed network of social contacts in the United States, stretching from west to east through fertile landscapes freed from the ice of the Pleistocene glaciation. However, it is impossible to say for sure whether obsidian reached the North by accident or whether it was a regular occurrence.