New research offers evidence that 'Mound A', one of the great earthen mounds at Poverty Point, Louisiana (USA), was constructed in less than 90 days.
     "Our findings go against what has long been considered the academic consensus on hunter-gatherer societies - that they lack the political organisation necessary to bring together so many people to complete a labour-intensive project in such a short period," says study co-author T.R. Kidder, PhD, professor and chair of anthropology in Arts & Sciences at Washington University in St. Louis.
     Co-authored by Anthony Ortmann, PhD, assistant professor of geosciences at Murray State University in Kentucky, the study offers a detailed analysis of how the mound was constructed some 3,200 years ago.
     Part of a much larger complex of earthworks, Mound A is believed to be the final and crowning addition to the 280-hectare site, which includes five smaller mounds and a series of six concentric C-shaped embankments surrounding a small flat plaza along the river. At the time of construction, Poverty Point was the largest earthworks in North America.
     Mound A covers about 50,000 square metres and rises 22 metres above the river, requiring around 238,500 cubic metres of soil. The site was cleared by burning and quickly covered with a layer of fine silt soil. A mix of other heavier soils then were brought in, building the mound layer upon layer. "The Poverty Point mounds were built by people who had no access to domesticated draft animals, no wheelbarrows, no sophisticated tools for moving earth," Kidder explains.
     To complete such a task within 90 days would require some 3,000 labourers. "Given that a band of 25-30 people is considered quite large for most hunter-gatherer communities, it's truly amazing that this ancient society could bring together a group of nearly 10,000 people, find some way to feed them and get this mound built in a matter of months," Kidder says.

Edited from Washington University, Saint Louis (28 January 2013), and Past Horizons (31 January 2013)