In the last decades, geophysical methods such as magnetic survey have become a common technique for prospecting archaeological sites. At sub-Saharan archaeological sites, however, magnetic survey and correlated techniques never came into broad use and there are no signs for an immediate change of this situation. This paper examines the magnetic survey undertaken on the Nigerian site of Zilum, a settlement of the Gajiganna Culture (ca 1800-400 BC) located in the Chad Basin and dated to ca 600-400 BC. By means of the present case study, we demonstrate the significance of this particular type of investigation in yielding complementary data for understanding the character of prehistoric settlements. In conclusion, we point out that geophysical methods should play a more important role in modern archaeological field research, as they furnish a class of documentation not achievable by traditional survey and excavation methods, thus creating new perspectives for interpreting the past of African societies.
Within the scope of a short-term pilot study, the authors conducted trial geophysical surveys at two sites of the late Holocene food-producing Kintampo Complex (ca. 2100-1400 BC) in northern Ghana. Overall goal of research was an evaluation of the potential of employing geophysical prospecting to map the subsurface extent of Kintampo open-air settlements. From an archaeological viewpoint, the results of the surveys were satisfactory but not outstanding in view of post-depositional disturbances at the locations. Based on that knowledge, we argue for the need of developing a systematic archaeological reconnaissance and research program for locating new and virtually undisturbed open-air Kintampo sites. We maintain that such a preliminary measure will be crucial both for investigating hitherto neglected research issues such as Kintampo settlement pattern and landscape exploitation as well as allowing geophysical technologies to fully evolve as central explorative tools in regard to settlement-related spatial questions.
In the last few years, archaeological investigations carried out at the mid-first millennium BC settlement site of Zilum, Nigeria, have integrated magnetic survey, a geophysical technique, as an additional source of information. Amongst other results, the magnetic survey revealed the presence of an archaeological feature that encloses the entire settlement area. Excavations show that this feature consists of a ditch. Dimensions and shape suggest that its function was to restrict access to the settlement. Although direct evidence is missing, the ditch was most probably accompanied by an earth rampart or wall, now completely decayed. Based on the available data, it seems likely that Zilum was a fortified settlement.