A petrographic study of the anthropomorphic stelae from the Megalithic Area of Saint-Martin-de-Corléans (Aosta, Northern Italy),

The Megalithic Area of Saint-Martin-de-Corléans (Aosta, northern Italy) consists of anthropomorphic stelae dated to the Copper Age and the beginning of the Early Bronze Age. They were carved in different lithologies of varying provenance according to two successive artistic styles, ‘ancient’ and ‘evolved’. A minero-chemical and a petrographic investigation were carried out on 47 stelae and on reference samples collected from eight different outcrops, aiming to define the provenance of the stone materials. The variety of rocks used for the manufacture of the stelae reflects the geological complexity of the Aosta Valley. Most of the stelae examined were classified as foliated impure marbles, grey banded marbles (‘Bardiglio’), calcschists and metabasites belonging to the Combin Zone (Piedmont Nappe), which outcrops in close proximity to the Megalithic Area. Some stelae of the evolved group consisted of massive marbles with silicate-bearing layers, attributed to the Sion–Courmayeur Zone. Similar stone materials were reported for the stelae of the same age found at the archaeological area of Petit Chasseur (Sion, Switzerland). This is archaeometric confirmation of the archaeological affinity between the stelae occurring at the two prehistoric sites, supporting the hypothesis of cultural exchanges over the Grand St Bernard Pass since the Early Copper Age.