During its development years, geophysical survey has served field archaeology by defining possible sites underground, prior to excavation or preservation. Now we can see the art taking off as a research method in its own right. After summarising some recent research applications of magnetic mapping, the author gives us three case studies from USA and Jordan, where ground-penetrating radar (GPR) has produced new interpretations of prehistory and history. Since GPR can map in horizontal slices without damage, it opens up important heritage preservation options. In one case, excavation was discouraged on ethical grounds, in another it was inhibited by the presence of later monuments and in a third, an early agricultural site, the GPR actually saw more than the excavators. This presages a research tool of particular power.

Over three field seasons between 2007 and 2012, we excavated three caves—Mota, Tuwatey, and Gulo—situated at an average elevation of 2,084 m above sea level in the cool and moist Boreda Gamo Highlands of southwestern Ethiopia. Anthropogenic deposits in these caves date from the Middle to Late Holocene (ca. 6000 to 100 BP) and provide excellent preservation of material culture, fauna, flora, and human skeletal remains from which to investigate changes in technologies and habitat use over the last several thousand years. Here, we present results and interpretations, suggesting ways in which Holocene communities of the Boreda Gamo Highlands constructed new landscapes and technologies in their transition from hunting and gathering to an agropastoral way of life. Entre 2007 et 2012, au cours de trois missions de terrain, nous avons fouillé trois grottes---Mota, Tuwatey et Gulo---situées à une altitude moyenne de 2154 mètres au dessus du niveau de la mer. Sur le haut plateau au climat froid et humide de Boreda Gamo, dans le sud-ouest de l’Éthiopie. Les gisements anthropiques dans ces grottes datent de l’Holocène moyen à tardif (environ 6000 à 100 BP) et présentent une excellente conservation de la culture matérielle, de la faune, de la flore et des restes humains, à partir desquels ont pu être étudiés les changements technologiques et dans les modes d’occpation au cours des derniers millénaires. Nous présentons ici les résultats et les interprétations, proposant les modalitiés par lesquelles les communautés holocènes des hauts plateau du Boreda Gamo ont construit de nouveaux paysages et technologies pour passer de la chasse et de la cueillette à un mode de vie agropastoral.

Ground-penetrating radar processing and interpretation methods have been developed over time that usually follow a certain standard pathway, which leads from obtaining the raw reflection data to the production of amplitude slice-maps for three-dimensional visualization. In this standard series of analysis steps a great deal of important information contained in the raw data can potentially be lost or ignored, and without careful consideration, data filtering and re-analysis, information about important buried features can sometimes be unobserved. A typical ground-penetrating radar (GPR) dataset should, instead, be processed, re-evaluated, re-processed and then new images made from new sets of data as a way to enhance the visualization of radar reflections of interest. This should only be done in an intuitive way, once a preliminary series of images are produced using standard processing steps. An example from data collected in an agricultural field in France illustrate how obvious buried features are readily discovered and interpreted using standard processing steps, but additional frequency filtering, migration and then re-processing of certain portions of the data produced images of a subtle Roman villa foundation that might have otherwise gone undiscovered. In sand dunes in coastal Brazil, geological complexity obscured the reflections from otherwise hidden anthropogenic strata, and only an analysis of multiple profiles using different scales and processing allowed this small buried feature to be visible. Foundations of buildings in a Roman city in England could be easily discovered using standard processing methods, but a more detailed analysis of reflection profiles after re-processing and a comparison of GPR images with magnetic gradiometry maps provided information that allowed for the functions of come buried buildings and also an analysis of the city’s destruction by fire.