Iron Age stelae in the Flinn strain diagram

Abstract

A recurrent, but often difficult issue when studying lithic monuments from the past is to determine both the origin and location of the corresponding source rocks.Addressing these questions necessarily requires an integrated archeological/geological approach that can be successfully applied when the megaliths under study display diagnostic physical attributes. This is the case for four Iron Age cigar-shaped stelae from SW Brittany (France) that typically show L>S and L tectonite fabrics similar to those of the Ordovician Nizon orthogneiss. Our integrated approach provides a better understanding of the criteria used by Iron Age people in selecting rock material, and the four Iron Age monoliths under study can be viewed in some ways as a pioneer application of the Flinn strain ellipsoid concept. Our work also emphasizes the prominent development of L tectonites in the eo-Variscan basement in SW Brittany, synchronous with sinistral ductile shearing and orogen-parallel elongation.

An interdisciplinary approach to Late/Final Neolithic coastal gallery graves in Brittany, Western France: The 3D structure, origin of stone material, and paleoenvironmental setting of the Kernic and Lerret monuments

“…The location of the exploited rock outcrops is most often based on the 1:50,000 geological maps produced by the BRGM (Bureau de Recherches Géologiques et Minières), while the potential sources of extraction are rarely researched (Chauris, 2009(Chauris, , 2021. Here, we present a new investigation of the Lerret and Kernic gallery graves, based on the methodology recently applied by Caroff et al (2016) and Le Gall and Caroff (2018) to Iron Age stelae in South Brittany. This approach involves the comparative petro-structural study of the material of both monuments and the exposed rock outcrops in their vicinity.…”