Spatio-temporal reasoning in archaeology with G.I.S.

Arnese A., Barsocchi S., Masserotti M. V.

Information Systems Applications 

The aim of the project was to create a system for recording, representing, manipulating and transforming archaeological surveys using GIS technology. The system relies on a geodatabase with administrative information of (municipalities where searches are carried out), archaeological (excavation and surveys) and documentary type Sources and documentation are associated with surveys. The database is an archive of: - excavations with areas, tests, stratigraphic units, tombs, individuals and finds, - surveys with UT (zones with a higher concentration of finds), - surveys with MS (zones with a lower concentration that does not necessarily identify a site, - lists of the relevant finds. In the planning stage, the data were normalized. During the system design we focused on the spatio-temporal reasoning, because GIS technology cannot manage time and space with the same granularity. Moreover, archaeologists often date the contexts of the materials discovered by comparing them with classifications and seriations?? that have already been processed. This dating system very rarely leads to exact chronologies (except in cases of known historical events or enclosed contexts). Besides the dating method, uncertainty is also due to dating by 'cultural stages': history is subdivided into periods such as the First Republican Age or the Middle Bronze Age. Such definitions, particularly for more ancient ages, can vary considerably in relation to geographic zone or culture. This is a crucial node in the modeling of an archaeological database, which is very much dependent on the temporal component and which is insufficiently defined. In GIS transposition of such chronologies, the main problem is the impossibility to identify one minimal unit of time - kronon - to represent the dates. Moreover, if a find has a continuous chronology, a site or an area of finds (TU) can have a period of 'no life' within its chronology. In order to meet these requirements, the dating of sites and finds is represented as a 'Period', with a beginning and an end expressed by numerical values representing the years (negative for the years before Christ and positive for those after Christ). This solution allows one to manage continuous and discontinuous intervals of time (representing them as sequences of beginning-end periods) and temporal events (when Beginning and End are identical). Uncertainty is represented as symmetrical 'tolerance' around the beginning and the end values of the period. GIS commercial technology was integrated for this project to handle such temporal reasoning and to answer such queries. The survey described in the paper concerns the entire territory of ancient Kaulonia, what is now known as Monasterace (Reggio Calabria), Italy. The system is currently being integrated with predictive models to locate new areas of archaeological

Source: International Conference on Geoinformatics and Geographical Systems Modeling and Fifth Beijing International Workshop in GIS, Beijiing, China, 2-4 April 2004