Artifact Analyses Dispute Assumptions About A Prehistoric Society

So say University of Illinois scientists, whose recent mineral analyses of red stone artifacts from Cahokia are upsetting an apple cart of important archaeological assumptions. Among other things, their study shoots down the idea that the great mound-building mecca in what now is southwestern Illinois traded extensively with distant cultures to the northwest.

One of several Middle Mississippian chiefdoms, Cahokia was inhabited from A.D. 700 to 1400, and at its peak at about 1100, it had a population of 20,000. Cahokia was the most sophisticated prehistoric native civilization north of Mexico, a culture that seems to have been focused on religion. The new findings about the ancient culture are discussed in the current issue of Plains Anthropologist.

Using X-ray diffraction and spectroscopic analysis, Thomas Emerson, an archaeologist, and Randall Hughes, a geologist, have discovered that most of the red stone fragments found at Cahokia are not made of the rare catlinite stone that originates in western Minnesota, but rather, are a more local Missouri red flint clay. This finding shatters the long-held belief that the presence of catlinite in Cahokia proved that the Cahokian people traded on a large scale with their Upper Mississippi River Valley neighbors. The new tests also show that the catlinite that was found at Cahokia arrived after the great Cahokian culture had disappeared – with Oneota people in the 14th century or with later protohistoric or historic groups in the 16th and 17th centuries.

Extensive trade, Emerson said, "is often touted as an important factor in early civilizations," but, based on the new evidence, such was not the case for Cahokia. "Essentially, our argument is that large-scale political and social complexity does not automatically entail large-scale economic networks."

False assumptions have always colored the study of red stone artifacts in general and red stone pipes in particular, the UI researchers wrote, including the general consensus that all aboriginal red pipes were made of catlinite. Because most investigators have been unable to distinguish between visually similar red siltstones, pipestone and catlinite, they have misidentified most archaeological specimens as catlinite. Moreover, until now, few mineralogical studies of red pipes have been conducted. The new study demonstrates that catlinite is mineralogically different from similar stones in that it doesn’t contain quartz. In their work, the UI team used a new piece of experimental equipment in the field: the Portable Infrared Mineral Analyzer (PIMA), which they are testing under a National Science Foundation grant. "The technique appears to be most useful as a first-line method of mineral identification and in those instances where destructive sampling is prohibited," the authors wrote.