The Cahokia Example
Woods, William I., Population nucleation, intensive agriculture, and environmental degradation: The Cahokia example. Agriculture and Human Values 21: 255–261, 2004.
Full text [here]
Dr. William I. Woods was in the Department of Geography, Southern Illinois University Edwardsville for 20 years and is now Director of the Environmental Studies Program and Professor in the Department of Geography, University of Kansas. For over thirty years he has been conducting prehistoric and historic settlement-subsistence research in the Eastern United States, Latin America, and Europe.
Abstract: Cahokia, the largest pre-European settlement in North America, was situated on the Middle Mississippi River floodplain and flourished for approximately three hundred years from the 10th century AD onward. The site was favorably located from an environmental standpoint, being proximal to a diversity of microhabitats including expanses of open water and marshes from which the essential, renewable fish protein could be procured. More importantly, the largest local zone of soils characterized as optimal for prehistoric hoe cultivation lay immediately to the east. Here, on the floodplain and along its bordering alluvial fans, the large maize outfields were situated, while the multi-crop house gardens were placed within the habitation zone on soils that had often been culturally enriched by prior occupation. As successful as this strategy might have been for small, dispersed populations in such a plentiful environment, nucleation of large numbers of people at Cahokia provided a different adaptive context that ultimately led to ruinous consequences. The seeds for the city’s destruction centered on anthropogenically produced environmental degradation. Demands on wood resources for fuel and construction were enormous and agricultural field clearance was in forested rather than prairie settings. The resultant watershed deforestation produced greatly increased rates of erosion, runoff, and unseasonable downstream flooding during the summer growing season. The economic and social consequences of declining production and localized crop failures proved disastrous for this city of farmers.
Selected excerpts:
One thousand years ago a city existed on the Mississippi River floodplain directly to the east of the present St. Louis. Called Cahokia after the historic aboriginal group who inhabited the site in the 18th century, this was the most extensive expression of population nucleation to have been produced prehistorically in America to the north ofMexico. The structure of the community was planned with clearly defined administrative/ceremonial zones, elite compounds, discrete residential neighborhoods, and even suburbs. An enormous central plaza and numerous immense earthworks provide evidence of high organizational skills and great expenditures of labor. With a population peak of perhaps 15,000 individuals, Cahokia existed for approximately three centuries (Fowler, 1997; Milner, 1998; Dalan et al., 2003)…
A variety of environmental niches within the American Bottom and adjacent uplands were present (Gregg, 1975; Welch, 1975). In the main bottom, ecological zones would have included annually submerged river edge woodlands, perennially inundated sloughs and other low areas, floodplain woodlands, extensive bottomland prairies, and oak-hickory forests on high, well-drained areas associated with a late Pleistocene terrace in the northeastern portion of the bottom (Goddard and Sabata, 1986; Wallace, 1978). In the bordering loess-covered uplands, the oak-hickory forest graded toward the east into circumscribed zones of woodland, savanna, and prairie vegetation, with large expanses of prairie only present well to the east and bottomland forest and prairie confined to the major watercourses. The great number and variety of microhabitats in the region would have sustained a high diversity of exploitable plant and animal populations…
Even during the Mississippian Period though, one cannot speak of a truly “natural” American Bottom landscape. The effects of many millennia of human occupation had resulted in great landscape change through the extirpation of local animal species; introduction of exotic plants (including domesticates); forest clearance for fuel, construction materials, and agricultural fields with attendant accelerated erosion and downslope deposition; localized enrichment of soils in habitation areas; the maintenance of prairies and removal of forest undergrowth through burning; and, perhaps, managed groves of nut bearing trees on the bluffs and bluff slope environments…
Native vegetation at the site consisted of grasses with scattered woodlands and forest found only as galleries along the watercourses. However, to the east, Cahokia’s five-kilometer radius catchment contains the largest zone in the American Bottom of soils characterized as optimal for prehistoric hoe cultivation (Figure 3). Here, on the silty alluvial overbank and fan sediments, the large, communally worked, maize outfields would have been located. Additionally, production would have been augmented by multi-crop house gardens within the site itself found on soils highly enriched by the debris from prior habitation activities, as well as from fields situated on vacated ancestral lands further upstream on the Cahokia Creek floodplain…
