By Julian Smith
The Poverty Point World Heritage Site covers almost three square miles of Mississippi River floodplain in northeastern Louisiana. The area was occupied by a hunter-gatherer culture as early as 1670 B.C. During a construction boom between 1470–1270 B.C., its inhabitants built five massive mounds and six concentric ridges around a central plaza, making it the largest earthworks in North America at the time. The largest mound, called Mound A, stands over seventy feet high and covers about 538,000 square feet. All of this happened without the use of domesticated animals or wheeled carts.
T.R. Kidder and his colleagues re-excavated Ridge West 3 to make a detailed stratigraphic analysis of how it was built. The first construction stage at the bottom of the trench is made from darker, heterogeneous materials in contrast to the upper stage, which is composed of lighter, homogeneous silt. The different colors and textures in the unit show that this ridge wasn’t a haphazard construction, but a purposefully engineered feature built to a plan. | Credit: Kelly Ervin
This LiDAR map of Poverty Point shows its mounds and ridges. The ridges are numbered one through six. | Credit: Kelly Ervin.
Poverty Point’s ridges are barely discernable in this photo. In the middle of the photo is a metal frame of a reconstructed hut that sits on an unexcavated portion of Ridge West 3. | Credit T.R. Kidder
Researchers have puzzled over how the builders moved a total of about twenty-seven million cubic yards of soil by hand. “The thought was that hunter-gatherers are simple cultures without the resources or political complexity to produce anything of this scale,” said T.R. Kidder of Washington University, who has worked at the site for over two decades. However the structures were built, he said, at first glance it’s easy to assume the efforts took decades, or even centuries. But the most recent results of Kidder’s research paint a very different picture.
A paper published by Kidder and Anthony Ortmann of Murray State University in Geoarchaeology in 2013 presented the first evidence that Poverty Point had been built much faster than had been assumed. Using micromorphological analysis and radiocarbon dating of samples recovered from Mound A, Kidder and Ortmann found no evidence that the soil forming the mound had been exposed to the elements for any detectable length of time while it was being built. This indicated that Mound A, the second largest mound north of the Valley of Mexico, was built in one nonstop effort, which the authors estimated could have taken as little as thirty days. Even Kidder and Ortmann were surprised by their results. Other experts were too, at least at first. But most were eventually convinced by the data and analysis. “It suggests we almost need to throw out our ideas of what hunter-gatherers are capable of,” Kidder said.
This is an article excerpt from the Winter 2021 edition of American Archaeology Magazine. Become a member of The Archaeological Conservancy for your complimentary subscription.