Integrating Geomorphology, Geology, and Geochemical Parameters to Understand the Preservation Status and Spatial Distribution of Archaeological Iron Objects Related to the 235 ce Roman–Germanic Harzhorn Conflict (Lower Saxony, Germany)

With more than 2000 excavated archaeological iron artifacts, the Roman–Germanic conflict site Harzhorn is among the best-preserved battlefields from Classical Antiquity. The Harzhorn hogback, with its steep front face oriented to the north, is situated perpendicular to an important north–south passage west of the Harz Mountains in central Germany. The geological setting shows abrupt transitions at the surface between different Triassic and Quaternary deposits. To investigate possible relationships between the preservation status and detection probability of iron artifacts and geology, geomorphology, and properties of the substratum, 497 samples were investigated in terms of the pH value, electric conductivity, loss on ignition, and grain size. These parameters were systematically compared to the distribution, type, and preservation status of recovered iron objects. The pH value proved to be the most significant indicator for the preservation status. Within increasingly acidic environments, the iron objects showed severe corrosion damages, whereas the same type of objects showed a good preservation status when recovered from areas with more neutral pH values. Additionally, historical and modern human impacts on the landscape modified the distribution of finds. We mapped in detail areas with good, intermediate, and poor preservation conditions, which should be considered in the reconstruction of the battle.