A Mississippian conflagration at East St. Louis and its political-historical implications

Fecal stanols show simultaneous flooding and seasonal precipitation change correlate with Cahokia’s population decline

“…2). The stratigraphic position of the decline in fecal stanols relative to the flood supports Munoz et al's (6) association between the timing of massive flooding of the Mississippi River and late 12th century sociopolitical changes in the Cahokia area that are indicated by evidence for regional population decrease, agricultural contraction, palisade construction, a significant reduction in the creation of new mounds, final capping of some mounds, catastrophic abandonment of some sites, and the reorganization of residential space at Cahokia (2,11,13,29,43). The majority (∼70%) of historical flood crests on the Mississippi River at Saint Louis (adjacent to Cahokia) occur in April-June, when crops are particularly sensitive to moisture and temperature (44,45).…”

“…Perhaps one environmental change would not have been consequential, but a combination of two or more changes would have presented significant challenges for a centralized, agrarian social system. Around this time, the inhabitants of Cahokia constructed a series of palisades that have been interpreted as indicators of societal stress (13), and several other lines of evidence indicate that there was a reorganization of Cahokia's sociopolitical structure, including the destruction of outlying population centers, decline in construction of earthen monuments at Cahokia, shifts in the prestige goods economy, and a contraction of agriculture (2,10,13,29,43,54). The construction of the first palisade at the time of flood event V, followed by repeated rebuilding during the period of decreased summer season precipitation, along with evidence for considerable change in other aspects of Cahokian society, implies that environmental events were significant factors synergistically associated with Cahokia's population decline and reorganization.…”

“…Because smaller sites contemporary with Cahokia's occupation are present in the watershed (2), and the proximity of a population to drainages and the lake may affect the amount of fecal stanols at each coring site, the Horseshoe Lake fecal stanol record (15) captures population change at the watershed level. However, Cahokia is the most likely candidate for controlling the lake's fecal stanol signature because HORM12 and 15HSL show parallel trends; the stanol trends in both cores closely track the Cahokia population estimates of previous demographic reconstructions (2,14); the footprint of Cahokia's inhabitants on the landscape likely expanded throughout much of the watershed through activities such as hunting, fishing, and gathering; modern hunter-gatherers (25) and rural farmers (26) without sewage systems frequently practice open defecation away from their homes, where much of their daily activities take place; archaeological surveys around Horseshoe Lake show fewer Mississippian Lohmann phase sites, c. 1050-1100 CE, compared with sites from the preceding century and a half, whereas within the watershed, the numbers of Lohmann phase sites and sites from the preceding phase are similar, which is evidence of shifting settlement locations associated with the rise of Cahokia (27,28); and Cahokia is the largest archaeological site in the watershed, followed by the East St. Louis Mound precinct near the watershed's southwest corner (29).…”

Cahokia’s emergence and decline coincided with shifts of flood frequency on the Mississippi River

“…Extensive inundation of the floodplain was unprecedented for the sociopolitical system established at Cahokia, and the return of large floods at ca. A.D. 1200 at the onset of regional depopulation (6), agricultural contraction (12), political decentralization (15), the construction of defensive palisades (42), destruction of outlying population centers (9,43), and decline of monumental construction at Cahokia (9) implicate flooding as a factor in the reorganization of Cahokia's sociopolitical structure that initiated its decline. In contrast to the large Mississippi River floods of the 19th century that fostered resilience and motivated legislation aimed at preventing damage from flooding (17), Cahokia's leaders appear to have been unable to maintain the impression of security and stability following the economic upheaval created by the return of large floods.…”

9 Elements of Cahokian Neighborhoods

“…In this ritual‐residential or civic‐ceremonial core, the low density of domestic debris suggests it was occupied by a small group of priestly or elite caretakers who were able to mobilize the labor necessary to modify the landscape and build mounds, specialized buildings, and their own oversized residences (Pauketat ). Near the end of the Stirling phase, a large‐scale conflagration destroyed the storage huts (Pauketat, Fortier, Alt, and Emerson ). Human interments within the pits that held decommissioned marker posts, the deposition of ritual paraphernalia (e.g., pipes, smashed vessels) concurrently with or immediately after the fire, and the decreased activity in this core in the subsequent Moorehead phase are suggestive of a closing ceremony possibly associated with a specific astronomical or historical event (Pauketat ).…”