University of South Alabama Undertakes Comparative Study on Remote Sensing in the Search for Fort Louis
Built by the French in 1702 to defend Mobile, Fort Louis de la Louisiane's exact location has long remained a mystery. The University of South Alabama (USA) recently concluded a PTT Grant project involving the comparative study of five remote-sensing technologies used to search for archeological remains of the fort.
In Dec. 2001, 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 NCPTT and the Friends of Old Mobile, Inc.
"This kind of side-by-side test of complementary technologies will eventually enable archeologists to predict which remote sensing techniques are most effective for specific soil and moisture conditions," Waselkov said. "At Old Mobile, remote sensing detected numerous subtle cultural features, although not the single, large, French colonial feature we know exists in the survey area, a result that suggests some refinement of geophysical technologies is still needed.c
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 group coordinated another PTT Grant, 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." he said. "You don't have to dig to get data, although some digging is necessary to interpret the electronic results."
Waselkov evaluated 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.
Surveys using the five non-invasive techniques yielded huge amounts 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," Waselkov said.
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 archeology 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.