GIS-based landscape analysis of megalithic graves in the Island of Sardinia (Italy)

Abstract

One of the most important megalithic groups in Western Europe in terms of number and characteristics is the group of over 200 monuments of various types in Sardinia. It now seems to be confirmed that the rise of the megalithic phenomenon was during the culture of San Michele of Ozieri (Late Neolithic, 4000-3300 B.C.E.). The Sardinian dolmen graves, however, had a maximum distribution during the Chalcolithic, as evidenced by most of the finds from excavations. The phenomenon also shows a close relationship beyond Sardinia and especially with the monuments of Catalonia, Pyrenees, non-coastal departments of French-midi, Corsica and Puglia.
 About 90 dolmen graves of various types have been investigated, namely the simple type, “corridor” type, “allée couverte” type, and others of uncertain attribution, located in central-western Sardinia, and particularly in a significant area of ca. 3500 km2 coinciding with the historical regions of Marghine-Planargia, Middle Valley of Tirso and Montiferru. This includes some 40% of all Sardinian dolmens. Locational trends and relationships with regard to landscape elements were studied with the aid of GIS methodologies such as viewshed and cost surface analysis. This allowed an evaluation of the role of visual dominance on the surroundings in relation to waterways and natural access routes.
 These dolmens enjoy an isolated positional character, being found more often in high plateaus, but also on low plateaus and hills. Although different concentrations are found in dolmenic graves, these do not seem to have any direct relationship among them, but their influence is apparently directed towards travel routes and sensitive elements of the landscape that have capabilities of territorial demarcation.
 The particular location emphasizes the significance of these monuments as territorial markers for segmentary societies. It seems that a dolmen was constructed according to the territory immediately surrounding it. This reinforces the hypothesis of there being a secondary task, in addition to that of burial, to symbolize a message or landmark for those who moved towards "another" territory: a sign of belonging.

GIS-based landscape analysis of megalithic graves in the Island of Sardinia (Italy)

“…The motifs of concentric circles with a single radial line have close comparisons with the engravings present on some standing stones of the territory of Mamoiada, and in particular on the monumental Stele of Boeli (Fadda 1997;Atzeni 1998;Manca & Zirottu 1999). Outside of Sardinia, these figurative motifs are found in megalithic monuments of the Irish, for example in the megalithic necropolis of Loughcrew (Co. Meath) (Shee Twohig 1981: 202-220) and on the monumental standing stone of Ardmore (Co. Donegal) (McNally 2006: 98).…”

“…As regards the area under examination, besides information provided by the researchers mentioned above, there are only signalings of single dolmenic monuments: for example, in the works on the historic regions of Marghine and Planargia (Moravetti 1998b; and on the areas of Cuglieri (Pes 2009), Sedilo and Aidomaggiore (Tanda 1996;, Abbasanta and Norbello (Cicilloni 1997;Usai 1999), Narbolia (Usai 2005), Neoneli (Loi 2012), and Bonarcado-Seneghe (Maisola 2012).…”

“…The GIS methodology for the study of the archaeological landscape has been applied till now only on sites and monuments of protohistoric age (see for example, Puggioni 2009; Angius et al 2010Angius et al , 2012de Montis & Caschili 2012;Fenu et al 2012;Sanna 2012;Vanzetti et al 2013;Cicilloni & Cabras 2014). …”

From the visual connections of the nuraghi of Sinis to the submerged nuragic city of Conca Illonis in the pond of Cabras.

“…Tutt'oggi gli archeologi dibattono sulla loro funzione tendendo a inquadrarli prevalentemente come linee di demarcazione tra "cantoni" in grado di dividere il RA Giuseppe Sanna territorio in diversi ambiti di dominio (Lilliu, 1998;Cicilloni, 2009), cioè come dei progetti di occupazione volti alla trasformazione produttiva del territorio, evolutisi poi in sistemi insediativi policentrici spesso accompagnati da un adiacente insediamento (Usai, 2018;Del Vais, 2016). Solo recentemente con l'avvento dei programmi informatici GIS ha preso sempre più piede l'avanzare di studi che combinassero le mappe digitali dei terreni (DTM) con le preesistenze archeologiche in modo da relazionarle alla morfologia territoriale (Cicilloni, 2019;Vargiu 2015;Usai 2011), alla vegetazione dell'epoca (Malavasi, 2023), o ancora sfruttare le funzioni del programma GIS traducendo in distanze, diagrammi e schemi i rapporti tra le architetture (Cicilloni, 2014;Castangia 2021;Cicilloni 2015a;Cicilloni 2015b;Panico 2017;Fois 2014;Merella 2014;Cicilloni 2018;Matta 2020;Velli 2021). Da questa consapevolezza parte la proposta di una metodologia che utilizzi la strumentazione GIS e le ortofoto disponibili nel geoportale della Regione Sardegna (www.…”