Cahokia$s Boom and Bust in the Context of Climate Change

During the early Mississippian Lohmann phase (A.D. 1050-1100), the American Bottom experienced a political and economic transformation. This transformation included the abrupt planned construction of central Cahokia, a large-scale influx of people to "downtown Cahokia," the abandonment of pre-Mississippian village settlements, the reorganization of farming in the Mississippi River floodplain, and the founding of the Richland farming complex in the Illinois uplands. New tree-ring-based records of climate change indicate that this rapid development occurred during one of the wettest 50-year periods during the last millennium. During the next 150 years, a series of persistent droughts occurred in the Cahokian area which may be related to the eventual abandonment of the American Bottom. By A.D. 1150, in the latter part of a severe 15-year drought, the Richland farming complex was mostly abandoned, eliminating an integral part of Cahokia$s agricultural base. At about the same time, a 20,000-log palisade was erected around Monks Mound and the Grand Plaza, indicating increased social unrest. During this time, people began exiting Cahokia and, by the end of the Stirling phase (A.D. 1200), Cahokia$s population had decreased by about 50 percent and by A.D. 1350, Cahokia and much of the central Mississippi valley had been abandoned.

Sourcing Busycon Artifacts of the Eastern United States

A review of the history of marine-shell chemical-sourcing efforts preceeds the introduction of this project. Atomic-absorption spectroscopy (AAS) was used to assay levels of Ca, Mg, Fe, and Sr, in 44 prehistoric Busycon carica and Busycon perversum specimens from the eastern United States. Control shells (35) were collected from food refuse in coastal archaeological sites from Long Island to the Mexico—United States border. Subject shells came from nine Archaic and Mississippian sites. Elemental ratios were clustered to derive a probable water-body origin for the nine artifacts. The influence of diagenesis, body part, and species was negligible, but geography heavily influenced the results. The three shells from Monks Mound indicated origin in tropical, eastern Gulf, and Atlantic water. The shells from the Indian Knoll, Mulberry, and Tatham sites appear to have originated in eastern Gulf waters. The shell from the Archaic-period Ward site seems to have come from tropical water.

A Second-Terrace Perspective on Monks Mound

Monks Mound is a premier example of monumental architecture occupying the center of Cahokia, the largest prehistoric Indian site north of Mexico. A massive slump on the so-called "second terrace" of the mound prompted geoarchaeological testing resulting in new data concerning the age and function of this enigmatic structure. These data support theory suggesting that construction of monumental architecture is most likely to occur early in the development of complex societies, in this case the Cahokia polity. It is concluded that Monks Mound was a purposeful political tool for the manipulation of mass psychology.

Solid Core Drilling of Monks Mound: Technique and Findings

Solid core drilling was used to provide guidelines for future excavation of Monks Mound at the Cahokia site. The objective was to study, within reasonable limits of time and finances, the internal structure of the largest earthen mound in North America. The process is described along with a discussion of its problems and limitations as applied to similar archaeological situations. Radiocarbon dates indicate construction over approximately 250 years, from A.D. 900 to 1150. Evidence of construction stages is described and used to arrive at an estimate of labor figures and the necessary sustaining population of the Cahokia settlement. It is suggested that most of the mounds at the site were built after the completion of Monks Mound.