Relation of ""Bonito"" Paleo-Channels and Base-Level Variations to Anasazi Occupation, Chaco Canyon, New Mexico

The authors -- a geologist, two archaeologists, and a paleoenvironmentalist -- re-evaluate the prehistoric evolution of Chaco Wash and its relationship to various stages of Anasazi occupation. A channel similar to the modern arroyo existed and evolved about A.D. 950-1100, and apparently led to some intricate cultural adaptations involving, for example, water-control features and great houses. At other times floodplains and playa lakes required other adaptations. Of particular significance is an evaluation of the role of a sand dune across the Chaco drainage at its intersection with Escavada Wash. This intersection was intermittently dammed, creating a unique and localized stratigraphic evolution of alluvium that does not follow regional models of stratigraphic chronology.