What Lies Beneath
July 18, 2001
Dr. Bill Hanna, right, Phyllis Scott of Warrenton, and Jim Olmstead of Nokesville run ground-penetrating radar over the Elk Run Church site.
From The Fauquier Times-Democrat, Wednesday, July 18, 2001 (with permission)Times-Democrat Staff Photo/Yayoi Ayukawa
Since last spring, significant progress has been achieved in uncovering the 1750s brick, Greek cross foundation of the Elk Run Anglican Church in Fauquier County. Community volunteers under the direction of volunteer archaeologist Dr. John Eddins, have opened 27 controlled excavation units to reveal the exact location and dimensions of the well-preserved foundation, the cruciform shape, and information about building techniques and materials.
The committee’s goal is to create a properly landscaped historical park that will include an outline of the church foundation, perimeter of the cemetery, and three educational interpretive signs providing information about the church, the cemetery and the Elk Run community over time.
Last December, machine-assisted excavation coupled with hand excavation confirmed an adjacent burial site. Petrone & Associates will now conduct technical remote sensing to help locate the boundaries of the church cemetery and the positions of graves within it.
Remote-sensing methods are used to non-intrusively locate objects or structural features underground. In order for these objects or features to be detected, they must have some electromagnetic property that differs from that of the surrounding soil.
The three most important remote sensing tools being used in Elk Run archaeological investigations are ground-penetrating radar, the electromagnetic method and magnetic-gradiometry.
The ground-penetrating radar used at Elk Run is a sled-shaped antenna that is pulled along the ground. It is attached to an electronic control unit, video display unit, color monitor and recorder. Its scan range will enable operators to see reflections to an approximate depth of 4 feet.
“Echoes” from GPR can result from reflections off of building foundations, grave shafts, cobbles, boulders, brick masses, the tap-root of a large tree, a large animal burrow, a pipeline, an electrical line, or pieces of metal, glass, ceramic, or plastic.
Pete Petrone, a former 39-year photographic specialist for National Geographic Magazine, used GPR in archaeology and forensic studies. In Egypt in 1987, his team discovered and remotely photographed a 4,600-year-old underground ship of Pharaoh Khufu at the base of the Great Pyramid on the Giza Plateau.
The electro-magnetic device generates a magnetic field, which in turn induces a magnetization in the soil or induces a magnetic field within a metal object. It can detect magnetic susceptibility to a depth of about 2 feet or conductivity to a depth of about 5 feet.
Magnetic gradiometry makes detailed measurements of the earth’s magnetic field and of its vertical gradient. The vertical gradient is valuable for highlighting the shallowest buried magnetic objects.
Information generated from the research will be made available on the Internet. Also, portable displays of pictures and artifacts are planned for public places throughout the county.