University of South Alabama, Office of Public Relations

October 5, 2005
Contact: Renee Paul, , USA Office of Public Relations, (251) 460-6640

USA Concludes Comparative Study of Remote
Sensing in the Search for Fort Louis

MOBILE, Ala.--The University of South Alabama Center for Archaeological Studies this week concluded a unique comparative study of five remote-sensing technologies used to search for archaeological remains of Fort Louis de la Louisiane. The French built the fort in 1702 to defend Mobile, the Gulf Coast’s first permanent European colonial town.

Situated on Twenty-Seven-Mile Bluff near Axis, Ala., the exact location of Fort Louis has remained a mystery since USA began its long-term archaeological study of the French colonial site of Old Mobile in 1989. With much of the town investigated, USA has now focused on locating the fort, as well as the cemetery where the explorer Henri Tonti and many settlers are buried.

In December 2001, Dr. Gregory Waselkov, director of USA’s Center for Archaeological Studies, initiated the first attempts to find the fort using three non-invasive remote-sensing technologies—earth conductivity, magnetometry and thermal imaging—with assistance from the National Park Service’s National Center for Preservation Technology and Training and from the Friends of Old Mobile, Inc.

With continued support from the Friends of Old Mobile, a non-profit organization founded in 1990 to preserve, explore and document the historic site of Old Mobile, Waselkov launched a second attempt in December 2004. The Friends organized field teams, recruited volunteers and coordinated a $33,400 grant from NCPTT, which allowed deployment of two additional remote-sensing techniques—electrical resistivity and ground penetrating radar—and to follow-up with excavations or “ground-truthing” to verify findings.

“All five of the methods involve using electronics to find out what’s below the ground without actually disturbing it,” Waselkov explained. “You don’t have to dig to get data, although some digging is necessary to interpret the electronic results.”

Model of Fort Louis is shown to the left. French built the fort in 1702 to defend Mobile, the Gulf Coast’s first permanent European colonial town.

In addition to locating the fort, Waselkov and the NCPTT wanted to evaluate the effectiveness of the five modern remote-sensing technologies in conditions common to the Gulf coastal plain, which includes large areas of Alabama, Georgia, Mississippi and Louisiana.

According to Waselkov, a survey of the area using the five non-invasive techniques yielded a huge amount of data. While some of the remote-sensing data initially seemed to indicate the locations of French colonial features, five weeks of ground-truthing at the site revealed that all of the identified anomalies could be attributed to later disturbances.

“We determined that many of the remote-sensing anomalies were real, but all those we checked turned out to be modern—mostly logging roads from the early 20th century,” he said.

The results were mixed, according to Waselkov. “The techniques worked fine—there just may not be many intact French colonial features in that part of Old Mobile, or disturbance by modern industrial use of the property may have obscured the faint remains of the historic fort.”

In the end, though, the remote-sensing project did lead to a most promising discovery—a large pit, which went undetected by all five remote-sensing technologies. Found in ground-truthing excavations on a portion of the site owned by Mobile County, the pit was likely a source of clay used by the French to build up floors or fill between beams in their half-timber style buildings.

Four times the size of other pits found at the Old Mobile site and loaded with French artifacts—mostly nails, roof tiles and Indian pottery—the newly-discovered pit could possibly be part of Fort Louis’ structural remains.

“We may have found part of Fort Louis,” Waselkov said. “I’m pretty sure we have, but we won’t really know until we find more and can put the pieces together.”

Waselkov believes these non-invasive techniques can be valuable tools when used in concert. He said all five should be employed because each provides very different, complementary results.

As for the future of the Fort Louis search, Waselkov said that the archaeology team has made progress in narrowing their search, thanks to this latest project, and they look forward to additional ground-truthing of the remaining remote-sensing anomalies at this important colonial American site.

“We knew finding the fort was going to be difficult,” he added. “We’ll just keep digging.”

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