Una terra protesa verso il mare. L’analisi territoriale dell’area tra Civitavecchia e Tarquinia (Lazio) tra VI e XV secolo.

The topographical research conducted over the last 40 years in the coastal region of northern Latium between the Marta and Marangone rivers has moved in different directions of investigation, contributing significantly to outlining the main lines of transformation of this area. The results of the most recent studies on the medieval chronologies of the area have been extensively used in this work, whose main objective was to understand the settlement dynamics between the 6th and 15th centuries and the factors that determined them. The methodology is based on the data collected from ancient and modern sources, which were not only analyzed according to the usual practice of archaeological investigation but were merged into a special GIS (Geographical Information System) dataset, one of the most powerful spatial analysis software tools currently used for archaeological research. The data were transformed into vector files and processed with specific spatial and geomorphological analysis algorithms to answer different research questions. The interpretation of the data made it possible to observe the changes in the population that occurred in the area as early as the end of the 2nd century A.D. and continued until the 16th century, also in relation to the productive characteristics of the area. It has been verified that in this region the abandonment of many Roman-age settlements did not cause a general depopulation of the area, but on the contrary a different transformation of the rural settlement, both in residential and productive forms, in agreement with what has already been observed for the settlements in the Marta Valley. The settlement pattern outlined for the chronologies of interest shows a greater concentration of settlements towards the more inland areas to the detriment of the coastal areas, which were decidedly more active in Roman times. A dynamic that has not been attributed to any phenomena, but which can be related to a normal reaction of adaptation to changed socio-political conditions, which, in the aftermath of the definitive deconstruction of the Roman-era structures, manifested itself in a more significant manner. Between the 7th and 8th centuries, it has been evidenced that the contrast between the Lombards and the Byzantines played an undoubtedly important role in influencing the location choices, at least by the Byzantines, through a ‘reoccupation’ of existing settlements along the border line. One certainly important element was the relationship between sea and land, which was completely changed in the Middle Ages: the sea, an economic attractor in Roman times, seems to have become a ‘detractor’ in the Middle Ages. Now it is no longer such a secure element and no longer plays an exclusive role within a changed economic system, now more focused on agricultural production for self-consumption and which also exploits waterways and segments of land mobility to move. The change described, not wishing to propose a reflection in deterministic terms, was also favoured by progressive climatic changes that altered the environment, forcing human communities to change their approach to land use. The in-depth study of land use between the 8th and 18th centuries shows that the change in political-social and climatic terms also influenced land use. The landscape examined, which has always been sparsely urbanized, seemed at first observation to have remained unchanged. However, a more detailed reading of the archaeological indicators and information from the analysis of documentary and cartographic sources revealed how it had been affected by moments of transformation. The analysis of land use has shown that its use in agricultural terms did not condition settlement choices, mineral deposits and particular ecopedological conditions, but on the contrary may have contributed to the maintenance of some settlements over others. This exploitation, however, must be contextualized in the sphere of local production where the use of the resources offered by a given environment is used to satisfy self-consumption and not for more structured commercial forms such as the later alum activity. Therefore, in the medieval view of a productive self-sufficiency aimed at satisfying the basic needs of medium-sized human groups, these kinds of peculiarities were certainly considered. The research conducted has revealed how the population distribution and settlement forms that developed in this region between the 6th and 15th centuries resulted from a combination of multiple factors that mutually conditioned each other. Among these, the resources offered by the surrounding environment seem to have played a major role well before the ‘rediscovery’ of alum, even if their concentration does not allow the Monti della Tolfa basin to be equated with more organized mining contexts, such as those from which the Tuscan mining castles originated. A detailed study of the methodologies used to identify the specific tracing of quarry marks in the mediaeval period will certainly contribute to furthering this theme, perhaps even highlighting new relationships between settlements and the productive capacity of an area.