In Ground-Penetrating Radar, Conyers and Goodman have provided a much-needed manual for the understanding and application of ground-penetrating radar (GPR) to archaeological investigations. When archaeologists envision the use of GPR, they often see a technology that will provide them with all the answers to their problems concerning buried archaeological resources. The authors have provided a detailed discussion of GPR and its application to archaeological field research. They have brought the complexities of GPR technology out of the realm of magic and into the field application level of the archaeologist.
They begin with an introduction of geophysical methods as applied to archaeology. In this section, they provide a basic background to the use of GPR and to the history of the application of GPR to archaeological investigations. They also provide a brief introduction to other geophysical techniques (e.g., resistivity, electromagnetic induction [conductivity], and magnetic susceptibility) that can provide complementary data to GRP surveys or may be used in place of GPR in those situations where GPR provides less than satisfactory data. This is an important issue, especially when one addresses the use of GPR (more discussion and examples are provided in Chapter 8). Resistivity, conductivity, and magnetic (including total field, gradient, and susceptibility) surveys provide a horizontal view of geophysical data related to physical properties of the earth within the context of an archaeological site. While these data sets provide a picture of the various physical changes, they do not provide much information on the depth of the cultural anomalies in the data set. GPR provides the depth measurement to the investigations. One other important fact that the authors bring out in their discussion is the use of appropriate methods. This has been a problem that has plagued the application of geophysical techniques to archaeological investigations in North America. In the past, American archaeologists may have utilized a single geophysical technique and found that it did not provide them with the information that they were seeking. Instead of reviewing the application of the technique to the specific site conditions, the archaeologists have often decided that the technique was not worth the effort and discontinue its further use. This is where a publication of this nature is invaluable to the noninvasive investigation of archaeological resources. It provides detailed information on the use and application of GPR to archaeological investigations.
Chapter 2 describes the GPR method. It provides a basic background into the operation of the GPR system. While the authors do not get into the theoretical discussion of GPR operations, they provide an excellent synopsis of the operation of a GPR system at the level at which an archaeologist with limited understanding of physics, mathematics, or other hard sciences can read and understand the basic concepts. The authors also provide discussion of negative factors (i.e., antenna frequency constraints, focusing and scattering effects, signal attenuation, and the near-field effect) which also affect the use of GPR in archaeological investigations and subsequent interpretation of the data.
Chapter 3 covers the field use of the equipment and survey methodology. The authors provide a limited discussion of various types of GPR equipment presently on the market. Field methodology discussions include recording field data and equipment, and software adjustments as well as orientation of survey transects and actual acquisition of GRP data. The discussion covers more than what is needed to acquire the data. It covers the preacquisition steps of calibrating the equipment and collecting data that can be used to determine velocities and calculate depths from the time information acquired during the actual survey.