Determination of the influence of soil parameters and sample density on ground-penetrating radar: a case study of a Roman picket in Lower Bavaria

Ground-penetrating radar (GPR) surveys are very much influenced by the site-specific physical properties, soil parameters and the sample density of the radar pulses. According to the electromagnetic theory, the transmission and reflection of electromagnetic waves is dominated by the conductivity, dielectric permittivity and the soil moisture. Therefore, it is advisable to measure these parameters in advance of a GPR survey. Commonly, this is not possible directly with the standard common-offset GPR arrays. To overcome this problem, we adapted and applied a direct method called time-domain reflectometry to a selected case study of the Roman picket Hienheim at the Raetischer Limes in Lower Bavaria. Furthermore, we present some important results relating to the profile spacing and orientation of GPR surveys and the site-specific soil parameters. The location and the identification of the archaeological features were successful by all geophysical methods. However, the application of all these geophysical methods like magnetometry, resistivity and GPR in addition with aerial photography and Airborne Laserscanning exemplifies the advantages of an integrated survey to achieve a comprehensive result of an archaeological site. The Roman picket of Hienheim shows up differently in all results, as each one traces the archaeological remains according to a specific physical parameter. Resistivity and radar are best to resolve buried stone structures like the walls of the picket or stone-filled ditches. In contrary, magnetometry benefits of the magnetic contrast between the limestone walls and the surrounding soil.     

Despairing at ‘A World Made New’? South Africa Encounters the Post-war Human Rights Idea

ABSTRACT

This article surveys the efforts of the South African state to respond to the reconfigured world that emerged after 1945. Focussed on those years around the adoption of the 1948 Universal Declaration of Human Rights (UDHR), it argues that South African governments and officials were well attuned to the rising threat of human rights. Drawing on South African archives, it demonstrates that representatives of late United Party and early apartheid era governments were insightful observers of the mortal danger universal human rights posed to the racialised ideological architecture which governed essentially all of the country’s politics and society. Paradoxically, the most avowed opponents of the new crusade for universal human rights perceived its significance with equal or greater acuity than those more enthusiastic about the nascent rights order.