A hand to the plough: A GIS based cartographical analysis of changes in elevation due to terrain modification and erosion in the settlement area of ancient Crustumerium

Plough zone archaeology is revealed to us by post-depositional processes that move, abrade, disperse, obscure and change the composition of surface find assemblages, biasing the interpretation of survey data. The tuff bedrock that is characteristic of the geology of large parts of Central Italy is well known to be prone to erosion, which has been accelerated due to the long and intensive agricultural exploitation of the landscape. In the case of the ancient Latin settlement of Crustumerium (North-Rome) the adverse effects of erosion on the preservation of the archaeological record have been stressed by several scholars. One of the objectives of the archaeological fieldwork on Crustumerium by the Groningen Institute of Archaeology, in collaboration with the Soprintendenza Speciale per i Beni Archeologici di Roma, is to investigate the nature and impact of these taphonomic processes for the archaeology of this ancient urban area. The current paper investigates the history of land-use on the site of Crustumerium on the basis of elevation information in topographical maps covering a period of a century. The authors will quantify the geomorphological changes on the basis of a diachronic analysis of digital elevation models generated and compared within a GIS. The result is a series of maps in which the degree of erosion and subsequently the expected preservation of subsurface archaeology is defined for the entire settlement area. Maps like this can help guide future research plans, but can also assist in the interpretation of currently available data.