Key Words: Ground Penetrating Radar, Clandestine Burials, Geophysical Applications in Anthropology, Historic Cemeteries introduction and purpose
Download 0.69 Mb. View original pdf
|
- Navigate this page:
- GPR in Archaeology with a Focus on Florida
| Figure 4. Calibration of velocity for GPR can be achieved at a site by burying highly reflective material at a known depth and then adjusting velocity (depth) as the GPR unit is moved over the buried item. Here, rebar is buried 50 centimeters below surface in a previously backfilled test unit at the site of a GPR survey. This allows fora good approximation of the type of soil the survey will encounter (Schultz and Gidusko, 2014). Once prepared, data is collected at set intervals along a transect and anomalies are noted on a log sheet as they are seen in real time. Careful information should also be kept about the presence of trees along transect lines, weather conditions, or anything else that may promote confusing noise in the reflection profiles during processing. For this survey, data was collected along 25 transects. After post-processing, anomalies were mapped onto the section of the site where the GPR survey took place. Excavations at the site continued based on information gathered during the GPR investigation. Regardless of type of site or situation which calls fora GPR investigation, these same steps should be adhered to Information about the site’s formation and use should be examined prior to survey the proper antenna frequency must be used based on information of possible anomaly types to be encountered the survey should be conducted on a grid system with transect intervals kept close information about possible noise-inducing agents should be recorded and finally, data must be processed. GPR in Archaeology with a Focus on Florida It was not long after initial attempts to utilize GPR for archaeological surveys began that its worth became apparent to researchers in the archaeological community, though perhaps ease of operability lagged behind utility by a few decades (Vickers and Dolphin, 1975; Imai et al., 1987; Conyers, 2004). Much of this intervening time has seen the creation of new, more readily accessible GPR units with a wider array of antenna frequencies, visualization capabilities, data storage, and post-processing options. These advances in the technology associated with GPR helped secure its role in future archaeological investigations for the foreseeable future becoming a mainstay of research agendas, conference presentations, and peer-reviewed journal articles. Ground Penetrating Radar, along with other archaeogeophysical technologies, is now regularly used in the CRM industry (Lockhart and Green, 2006; Johnson and Haley, 2006). This is likely due to its cost-effectiveness and consistently reliable results. Such extensive use in the realm of CRM, however, exposes both benefits to the continued use of GPR as well as some research deficits. Most archaeological research in the United States today, as it has for the past three decades, occurs in the CRM sector. This is due to several legislative acts, but especially due to the National Historic Preservation Act of 1966 and the Archaeological and Historic Preservation Act of 1974. This legislation was largely due to a growing recognition of cultural resources as finite and necessitating active preservation. Currently, more than two-thirds of the archaeologists conducting work in the United States represent CRM entities (Weymouth, 1986; Green and Doershuk, 1998; Lockhart and Green, 2006). The growth of CRM firms and the use of GPR are concurrent and highly intertwined. While this has meant the abundant collection of data utilizing GPR it also creates the unique situation in which much of this data is represented only in grey literature, not easily accessible or perhaps even often utilized after the completion of a project. While it is important to note the presence of this accumulated data and its obvious potential worth, this paper focuses primarily on research-driven and/or published examples of GPR use. The following examples provide a look at GPR applications in archaeology. The first example (Imai et al., 1987) provides a look at the early application of GPR; its efficiency and capability at a variety of sites in Japan are described as is a basic overview of the operation of GPR. The next two articles (Thompson and Pluckhahn, 2010; Thompson et al., 2014) show current applications of GPR to archaeological research. Contrasted with Imai’s research, these examples show the growth of GPR and its integration into the wider field methods used during field investigations. Download 0.69 Mb. Share with your friends:
|