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Vol. 7, No. 7: March 15, 2001

Using Ground Penetrating Radar in Archaeological Digs:
A Faculty Profile of Dr. Harry Jol

by Jennifer Smith, TTT Editor

Some said it wouldn't work. Numerous experts held that using ground-penetrating radar (GPR) as a tool to assist archaeological excavation in a cave would only produce poor, unusable results. GPR works by sending waves (analogous to radio waves) into the earth to identify if there are objects or anomalies below the surface. While GPR is commonly used as a tool in archaeological digs out in the open, it had never really produced good results in a cave environment, where one might expect waves to go astray and bounce off ceilings, ruining the results. But Associate Professor Harry Jol of UW-Eau Claire proved that GPR can indeed be a valuable tool even in a cave setting, and the results of an overseas research project he participated in are receiving international attention.

In the summer of 2000, Jol and a team of about fifteen others--faculty and students from a variety of U.S. campuses--took part in archaeological fieldwork in Israel at the Cave of Letters. The site is located in eastern Israel in the Judean Desert. The project lasted three weeks and was preceded by a shorter, preliminary research trip in 1999, during which project participants sought to determine whether or not a dig at the site would be possible.

The area is of historical interest because it was the site where Jewish refugees took shelter from the Romans in the second century C.E. and probably the first century C.E. The Cave of Letters project was led by Richard Freund, director of the Bethsaida Excavation Project at the University of Hartford in Connecticut. The expedition involved extensive GPR surveys of the land, cave explorations, climatic tests, other geophysical surveys, and extensive excavation. Items recovered included coins dating to the first and second century, a child's sandal, a comb, fabric, pottery, and human bones.

Jol was brought on board the expedition as a GPR expert. GPR can speed up archaeological work since it can be used--without actually breaking ground--to identify areas that will yield a lot of finds. As Jol stated, "The cave is too large to completely excavate, so the ground penetrating radar allowed the project to locate areas that could potentially lead to the discovery of artifacts." GPR was also used to help guide an endoscope--a tool used more commonly to view inside the human body--in order to map and excavate the cave. Jol created both 2-D and 3-D maps of the site.

Joining Jol was UW-Eau Claire student Chris Morton, an undergraduate who worked with a pentop computer in the cave, locating the finds on a map using geographic information systems (GIS). Morton also recorded information on artifacts and compiled a daily log of the research team's activities. "I was absolutely amazed at what I was taking part in," said Morton. "It was the coolest thing I have ever done."

The Cave of Letters crew hikes to the archaeological site
The Cave of Letters crew hikes to the archaelogical site with gear in tow. (Photo: Chris Morton, UW-Eau Claire)

Working in a desert environment provided some physical challenges, since daytime temperatures outside reached 120 degrees (within the cave, the temperature was approximately 75 degrees). The research team tried to avoid the extreme heat as much as possible, working early in the morning and later in the evening. As Jol commented to the Eau Claire Leader-Telegram, "The idea of bringing ground-penetrating radar and the endoscope together in this type of rugged environment was a first…and we got it all up and running and working."

Jol has been able to incorporate his research experiences into his classroom teaching at UW-Eau Claire. In an introductory geography course called "The Physical Environment," Jol discusses the desert environment and how physical and human factors relate in an extreme environment. In upper-level classes, he uses his work as a source of examples to discuss remote sensing techniques. He also teaches GIS using the Cave of Letters work to illustrate real-time data collection. An honors program seminar he taught and faculty development seminars have also provided venues for Jol to share his work.

Two documentaries about the Cave of Letters archaeological dig will air on television. The popular public TV series "Nova" is producing an episode that will air within the next year. Another documentary was shot by the University of Nebraska-Omaha.

Jol concludes "GPR should be part of any dig" and plans to return to Israel in the summer of 2001, where he will spend a total of three weeks at two sites, Bethsaida and Qumran. Jol praised UW institutions for their willingness to provide funding for technology-based research. He predicts that technologies that are useful in archaeological fieldwork will continue to get more portable in the future.

For more photos and information about the Cave of Letters expedition and its crew, see Prof. Jol and Chris Morton's website at

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