Small Roman Site in Croatia

Abstract

A small Roman building is used as a test case for the merging of ground-penetrating radar and magnetic gradiometry images to help understand what each method is displaying in both profiles and maps. At this site the foundations of the building, composed of weathered limestone, readily appear in magnetic maps as negative magnetic features, and the building’s general architecture can be discerned. The GPR amplitude maps only show a few linear features that are highly reflective, and the wall foundations are effectively invisible as they include few stones or vertical walls that reflect radar waves. When each of the individual GPR reflection profiles are viewed in two-dimensions the floors and some wall foundations are visible, and the magnetic readings associated with them show that the horizontal surfaces are composed of materials that are lower in magnetic susceptibility than the surrounding ground (likely clay or lime plaster material). There were holes dug through the floors after the structure was abandoned, filled with slightly magnetic material, which is likely sediment higher in organic matter than the surrounding units. An analysis of the GPR profiles shows that it is the edges of the holes cut through the floors that created the high amplitude reflections seen in the GPR amplitude maps, not the walls or wall foundations. Attached to his building is less substantial architecture interpreted as a courtyard enclosure and possible cooking area where fires were used, as the ground and artifacts found there are higher in magnetism.