High resolution GPR mapping of Late Bronze Age architecture at Kalavasos-Ayios Dhimitrios, Cyprus Thomas M. Urban a , Jeffrey F. Leon b , Sturt W. Manning b , Kevin D. Fisher c a Research Laboratory for Archaeology and the History of Art, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford OX1 3QY, UK b Department of Classics, Cornell University, 120 Goldwin Smith Hall, Ithaca 14853-3201, NY, USA c Department of Classical, Near Eastern, and Religious Studies, University of British Columbia, Buchanan C227, 1866 Main Mall, Vancouver V6T 1Z1, BC, Canada abstract article info Article history: Received 29 March 2014 Accepted 26 May 2014 Available online 4 June 2014 Keywords: Cyprus Late Bronze Age Kalavasos-Ayios Dhimitrios Archeology Ground-penetrating radar At the Late Bronze Age site of Kalavasos-Ayios Dhimitrios in southern Cyprus, the subterranean remains of previ- ously unknown buildings were recently discovered and mapped with ground-penetrating radar (GPR). Though the fine-grained calcareous substrate at the site was not necessarily ideal for GPR—exhibiting a high clay fraction, significant volumetric water content, and scattering rubble—the buildings were mapped in excellent resolution with sufficient detail to indicate walls, entry-ways, and other architectural details. This was achieved with a somewhat lower frequency antenna (250 MHz center frequency) than is commonly recommended in archeological geophysics. The 250 MHz system was employed in order to mitigate the potentially negative effects of the lossy substrate, which had proved problematic for past research using higher frequency antennas. Our work showed that excellent GPR results were possible in this substrate by simply lowering the antenna frequency, and that electromagnetic attenuation likely improved spatial resolution allowing for the detection of greater detail than might be expected. The resulting GPR findings offer a fresh perspective on this important archeological site, while indicating that conservative antenna selection is not only sometimes warranted, but may be crucial in some archeological GPR investigations. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Recent GPR surveys have successfully delineated a number of impor- tant architectural features at the Late Bronze Age site of Kalavasos-Ayios Dhimitrios (K-AD) in southern Cyprus (Rogers et al., 2012; Urban et al., 2013). The site exhibits a clay-rich, alkaline substrate with substantial embedded rubble and significant soil moisture content (as high as 27% VWC at 0.4 m). It has been previously noted in the archeological GPR literature that substrate conditions such as described above are poorly suited for GPR investigations (Conyers, 2013: 203–204), and it has long been known that electromagnetic attenuation, α, is more pro- nounced with higher antenna frequencies, often leading to greatly reduced penetration depths (Davis and Annan, 1989; Jol, 1995; Smith and Jol, 1995; Leucci, 2008). In order to mitigate the anticipated effects of α, in addition to scattering losses expected with the substrate at K-AD, a 250 MHz GPR system was employed for the investigation at hand; a somewhat lower antenna frequency than is most often recommended in archeological geophysics. While decreasing the antennae frequency may mitigate the effects of α, however, it does so at the expense of spatial resolution (e.g. Jol, 1995). This approach is therefore generally viewed as a compromise where greater probing depth is gained only at a loss of spatial detail. The majority of literature on the application of GPR to archeology endorses antenna frequencies of 400 MHz or greater, thus favoring the prospect of superior resolution as might be required for archeological interpretation. For example, L. Conyers—the most widely cited source on archeological GPR—claims to have used 400 MHz and higher for nearly all investigations, stating that he has found use for lower frequency systems in less than 5% of field investiga- tions (Conyers, 2012: 27). Additionally, Conyers has argued that with frequencies lower than 300 MHz, resolution adequate for archeological interpretation is not likely to be achieved: “With those antennas, resolution is diminished, making many subtle changes in beds and archeological features all but invisible in GPR pro- files and maps.” (Conyers, 2006: 144). In contrast, Goodman and Piro (2013: 74–76) have recently noted that archeological GPR data can often be improved by lowering the antenna frequency and increasing sampling density. This approach is supported by the present study and has also proven effective in recent studies on similar sites. For example, GPR work in substrate conditions similar to K-AD has recently revealed the largest known Chalcolithic vil- lage plan in the lower Galilee of Israel, with GPR results indicating walls, rooms, and silos hidden beneath—in some instances—more than 1.0 m of clay (Urban et al., 2014); this was achieved with a 250 MHz system. Like the aforementioned study, the GPR investigation at K-AD revealed many architectural features at a spatial resolution suitable for Journal of Applied Geophysics 107 (2014) 129–136 E-mail address: thomas.urban@rlaha.ox.ac.uk (T.M. Urban). http://dx.doi.org/10.1016/j.jappgeo.2014.05.020 0926-9851/© 2014 Elsevier B.V. All rights reserved. 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