Archaeologists Identify Oldest Existing Mound Complex In New World

The complex of 11 mounds located near the town of Watson Break in northeast Louisiana was built between 5,000 and 5,400 years ago and predates other known existent mound complexes by 1,900 years, according to Joe Saunders, adjunct professor of geosciences at Northeast Louisiana University, who directed the project. He said a single burial mound found in Canada predates the Watson Break site and another now destroyed mound in Louisiana discovered in the1960s also may have been older.

Saunders said archaeologists remain puzzled by such mounds, which are earthen structures several meters high. The mounds might have served a mix of religious, agricultural or domestic purposes but give indications that they only could have been built with planned engineering, he said. Saunders and his colleagues have been able to piece together a picture of life at the newly discovered site. They found that hunter-gatherers lived at Watson Break seasonally, living on river animals and plants. These people caught fish from spring to fall and also ate turkey, deer, raccoon and other animals. In addition, seeds found at the site indicate the mound dwellers collected plant species that later became the first domesticated plants in eastern North America, Saunders said.

Feathers' contribution to the project was to date soil sediments found in mound fill using a technique called thermoluminescence. It uses heat and light to measures the number of electrons trapped in crystalline material and then calculates how long they have been trapped. Feathers operates the only thermoluminescence dating lab in the US that works with archaeological material.