TUCSON, ARIZONA—A new analysis of the Mitchell Log, the largest marker post recovered from Cahokia, has yielded dating information for the ancient North American city and insight into how marker posts were obtained by its residents, according to a Phys.org report. Nicholas V. Kessler of the University of Arizona and his colleagues used advanced tree-ring radiocarbon dating techniques and strontium stable isotope analysis in their study of the…..