Q&A on geophysics in archaeology with Research Associate Brian Damiata

Magnetic surveying at a Neolithic site in China

What is geophysics and how is it used in archaeology?
Geophysicists use a variety of black-box instruments to collect measurements, usually along the ground surface, of some physical property of the subsurface. This physical property may be electrical, electromagnetic, magnetic, or seismic in nature. Based on both the measured values and the spatial variations of these values, we try to discern what is below the ground surface. Interpretation of data, however, is seldom straightforward because perceived “anomalies” may be due to either human activities or natural variations in subsurface conditions.

The typical archaeological project of today uses a multidisciplinary approach incorporating expertise from diverse fields. Geophysics can be helpful in pinpointing areas of interest and guiding the allocation of resources for excavation. In addition, there is an increasing emphasis lately on the preservation of sites by limiting the size of excavations. In this instance, geophysics can be useful in delineating the total extent of sites and by providing a subsurface picture of the untouched areas.

In many respects, the use of geophysics as applied to archaeology is still in its infancy. As compared to its application in the oil, mining, and groundwater industries, the use of geophysics in archaeology presents difficulties because extremely high resolutions and instrumental sensitivities are required in an environment (the shallow subsurface) that has inherently high levels of “noise” and sources of present-day cultural interference.

What applications seem particularly useful in archaeology?
I have been using time-lapsed thermal infrared (TIR) images. Observed ground temperatures are partly affected by the thermal properties of the material within the shallow subsurface. Buried archaeological features such as walls and graves can give rise to temperature anomalies at the ground surface of the order of tenths of a degree or more. So, the objective is to develop rigorous methodologies for the collection and the quantitative interpretation of TIR data in order to determine subsurface thermal structure and ultimately the delineation of archaeological targets of interest.

Because many archaeological objects and sites (for example, the location of naval battles) lie undetected below sea level, underwater archaeogeophysics could be of use developing capabilities for using side-scan sonar and underwater magnetics. In order to investigate some of these possibilities, I am planning to get certified for scuba diving.

What are some of your upcoming fieldwork projects?
I’ll be returning to Iceland this summer for a second field season as part of the Skagafjordur Archaeological Settlement Survey being directed by John Steinberg. We are using electrical and electromagnetic methods to help detect and delineate Viking-age turf structures. In the fall, I’ll be joining Elizabeth Carter on her project at Domuztepe in Turkey. There we’ll be using magnetic and electromagnetic methods to try and locate burnt deposits. In the planning stages is a trip to Egypt as part of Willeke Wendrich’s project in the Fayoum. In addition, I have ongoing collaborations with personnel at the University of Athens and at the Shaanxi Archaeology Institute in Xi’an, China.