A study led by Dartmouth College with multi-sensor drones has revealed a large circular ground motion in what could be Lying down, an ancient city in what is now Wichita, Kansas.

Archaeologists speculate that the site was visited in 1601 by a Spanish expedition, led by Juan de Oñate, who described it as a ‘great settlement’. The earthworks may be the remnants of a so-called “council circle”, as it is similar to several other circular earthworks. in the region, according to study findings published in American Antiquity.

“Our findings demonstrate that undiscovered monumental earthworks may still exist in the Great Plains. It just takes a different archaeological approach to recognize them, “lead author Jesse J. Casana, professor and chair of the department of anthropology at Dartmouth College, explained in a statement.” Our results are promising in suggesting that there may be many other impressive archaeological features. That haven’t been documented yet, if we look hard enough, “he added.

The archaeological elements have several thermal effects. After the ground cools overnight, things under the ground cool and emit heat at different rates, allowing researchers to identify characteristics based on thermal infrared radiation. The researchers obtained thermal and multispectral images of the site using drones.

The 18-hectare area of ​​the site where the study with drones currently houses a ranch property in the lower valley of the Walnut River, which has been used as pasture. Topographically, the area is flat with no visible archaeological features. However, the images show that underground there is an old circular ditch measuring 50 meters wide and about 2 meters thick that has been filled in. As the soil erodes, it fills the trench with a different type of soil than it was before and therefore holds water in a different way, giving it unique thermal properties. Water retention levels also affect vegetation.

Using near-infrared images, the researchers were able to identify areas that had been filled in because grass growth it was more vigorous. As the study reports, the results provide evidence for what may have been a “unique and expanding population center” in its day.

To confirm that the findings were not an anomaly, the team compiled a time series of aerial and satellite images from the area of ​​the US Department of Agriculture and other federal agencies. They found that the circular feature was “slightly visible in June 2015 and July 2017, but not June 2012 or February 2017.”

The debate is extensive as to what the council circles were used for, were they astronomical in nature, or were made with ceremonial purposes, political and / or defense. Casana added: “While we may never know what the council circles were used for or their meaning, new archaeological methods allow us to see that people made these earthworks.”