Release Date: October 30, 2002
DENVER, Colo. -- Using non-invasive geophysical tools -- and without turning one shovel of soil -- a team of University at Buffalo scientists has discovered in the Jordanian desert an ancient Nabatean settlement buried beneath a 2nd-century Roman fort, which itself is buried a few feet below the desert surface.
They did so relying on electrical resistivity data, magnetic-field information and ground-penetrating radar, noninvasive geophysical techniques that are becoming increasingly important at sites of archaeological significance.
Preliminary results of the fieldwork, conducted this past summer, were presented here Tuesday (Oct. 29, 2002) at a meeting of the Geological Society of America.
"Without additional excavation, we have confirmed that a settlement was there," said Gregory S. Baker, Ph.D., UB assistant professor of geology and leader of the UB team.
The team included UB graduate and undergraduate students, working with an archaeological team from the University of Victoria in British Columbia, Canada, in collaboration with the Department of Antiquities of the Hashemite Kingdom of Jordan.
Because of its interest in increasing tourism as a major sector of its economy, the Jordanian government has a keen interest in discovering as much as possible about the archaeological treasures within its borders.
The Nabateans, possibly the most advanced civilization that existed 2,000 years ago, were known for dramatic tombs and temples they carved into sandstone, as well as their ingenious agricultural and irrigation practices. The Nabatean kingdom ruled parts of what are today Jordan, Syria and Israel. It was conquered by the Romans in 106 C.E.
The site where the UB work was done, Humayma, located about 3.5 hours south of the capital city of Amman, is the earliest ancient Roman fort in Jordan.
According to Baker, noninvasive geophysical techniques are becoming increasingly important at sites of archaeological significance because of the ongoing balance between the need to preserve a site's integrity and the desire to excavate.
"If you leave it buried, then you can be sure it's preserved," said Baker, "but if you dig it up, then people can view firsthand the contributions of these ancient civilizations.
"These noninvasive geophysical tools allow us to leave much of the site intact and preserved, while providing the Jordanian government with the information it needs to decide how it can most judiciously select a few important places at the site to excavate," he said.
To discover what lay as far as 6-10 feet underground, the UB team used three state-of-the-art, noninvasive, surface geophysical techniques.
Baker added that such techniques are far more sensitive than those based on satellite data.
Electrical resistivity was used to determine the presence of archaeological features, such as stone walls, based on the contrast between their electrical resistance and the surrounding loose sand and soil. To gather electrical resistivity data, the UB researchers towed along the sandy ground two antennas (resembling a pair of skis) connected to a data-recording device.
Magnetic gradiometry was used to measure variations in induced magnetism, the secondary magnetic field generated by materials in the presence of the earth's strong magnetic field. Different materials, such as stone, mud brick and loose sand have different strengths of induced magnetism.
To gather these data, two highly sensitive, fist-sized magnetometers, mounted on a small cart, were pulled along the ground.
Ground-penetrating radar, which Baker described as similar to aircraft radar but pointed toward the ground, was used to detect reflections from buried objects using pulses of electromagnetic energy. These data were obtained by a unit that looks like a lawnmower, in which the transmitting and receiving antennas are located in the housing underneath the wheel frame.
"Archaeologists and historians know that the Romans were incredibly organized and this carried through to their architecture, as well," he said, noting that all walls in Roman forts and structures are either parallel or perpendicular to the structure's perimeter.
"But what we found based on our studies was a series of walls that were off angle, and together with our collaborators, we have concluded that these were older than those of the Roman fort and therefore likely Nabatean buried structures," he said.
The work was presented by Heather Ambrose, a master's-degree candidate in UB's Department of Geology and a recent graduate of UB's undergraduate anthropology and geology programs. Her work in Jordan is being funded by a competitively awarded fellowship from the Taggert Foundation.
The team from the University of Victoria was led by John Oleson, Ph.D., whose funding through the Social Science and Humanities Research Council of Canada also supports some of the UB work.