13-2024, tome 121, 3, p.485-539 - Grégor Marchand, Laure Déodat, Alain Braguier, Solène Denis, Mikaël Guiavarc’h, Fabrice Redois, Sylvain Soriano, Olivier Troccaz, Erwan Vaissié, Antoine Zanotti, avec la collaboration de Philippe Forré — Des roches et de

Des roches et des hommes

Les matières premières et leur exploitation par les populations préhistoriques en Maine-et-Loire

Grégor Marchand, Laure Déodat, Alain Braguier, Solène Denis, Mikaël Guiavarc'h, Fabrice Redois, Sylvain Soriano, Olivier Troccaz, Erwan Vaissié, Antoine Zanotti, avec la collaboration de Philippe Forré

Résumé : Le département de Maine-et-Loire, implanté sur les marges orientales du Massif armoricain et celles occidentales du Bassin parisien, offre un formidable champ d'investigation pour tout lithicien travaillant sur les dynamiques d'acquisition et de circulation des matières premières siliceuses exploitées par les populations préhistoriques. Mais, préalablement à toute étude géo- ou pétroarchéologique, un inventaire de l'ensemble des ressources potentiellement disponibles et exploitables, et aussi exhaustif que possible, s'impose. Ce sont ainsi plus de deux cents échantillons de roches, aux qualités clastiques extrêmement variées, allant des cinérites carbonifères aux silcrètes du Cénozoïque, en passant par une multitude de silex jurassiques, qui ont été collectés, décrits, photographiés, cartographiés et rassemblés au sein de la lithothèque PETRA de l'UMR 6566. Au travers de plusieurs assemblages lithiques, allant du Paléolithique à l'âge du Bronze, nous pouvons apprécier toute cette diversité de roches, leur circulation dans un territoire fortement influencé par l'axe ligérien, et les modalités d'exploitation propres à certains matériaux. Le but ultime de cette base de données, présentée dans un système d'information géographique (SIG), mise en ligne et accessible pour tout public, est qu'elle devienne une référence à toute personne s'intéressant à ce sujet, aussi bien pour les études portant sur le département de Maine-et-Loire, que sur l'ensemble des Pays de la Loire, voire en dehors de la région.

Mots-clés : Gîte, matière première, Maine-et-Loire, Préhistoire, Protohistoire, roche.

Abstract: The Department of Maine-et-Loire, located on the eastern margins of the Armorican Massif and the western margins of the Paris Basin, offers a remarkable opportunity for lithic specialists to study how prehistoric populations acquired and circulated siliceous raw materials. This type of study must first and foremost involve the detailed inventory of all potentially available and exploitable resources before engaging in any geo- or petroarchaeological studies. The landscape of this department, located at the crossroads of the Paris Basin and the Armorican Massif, has a complex geological history that we aim to reconstruct and to understand in a historiographical chapter that presents the major scientific figures who have contributed to this research (chapter 1). This leads on to a detailed presentation of the geology of Anjou (chapter 2). Chapter 3 outlines the methodology from field sampling to database construction, including the necessary terminology, analyses, and a presentation of archaeological collections. Chapter 4 highlights the knappable materials of the Maine-et-Loire and outlines the online database Petra and the catalogue that brings together nearly a hundred samples of rocks, with extremely varied clastic qualities ranging from Carboniferous cinérites to Cenozoic silcretes, and including a multitude of Jurassic and Cretaceous flints. Samples have been collected, described, photographed, mapped, and assembled into a lithothèque that presents an evolving database to be refined and reinforced during future research. This work has demonstrated the great variability of knappable materials in the Department of Maine-et-Loire. On the one hand, an outcrop may yield different facies or sub-facies. On the other hand, the macroscopic characteristics of each sub-facies can vary greatly from one sample to another. Selected lithic assemblages dating from the Paleolithic to the Bronze Age show the diversity of rocks, how the Loire influences their circulation within the area and the methods used to extract them (chapter 5). This brief diachronic overview of the exploitation of raw materials in Maine-et-Loire shows the specificities of each chronological period. In the earliest periods, Neanderthal populations selected a wide variety of siliceous resources, indicating an excellent knowledge of the area they lived in. During the Late Glacial period, hunter-gatherer groups focused on local materials, derived from the ancient terraces of the Loire. The exploitation of opal-resinite, for example, seems to be specific to Neolithic agro-pastoral populations. In the Bronze Age, opportunistic lithic production focused on local poor quality bartonian-ludian silcretes. The ultimate aim of this database, presented in a geographic information system with open online access, is for it to be considered as a reference for anyone interested in this subject, both for studies centered on the Department of Maine-et-Loire and the entire Pays de la Loire region. Furthermore, this work has highlighted the significant variability of the materials that can lead to difficulties when identifying raw materials in archaeological assemblages in particular sub-facies. This remains perceptible in archaeological corpora. However, correlating variability from macroscopic classification with the identified geological variability remains complex. This level of detail demands an approach that includes petrographic analysis of the materials presented in this study at the microscopic scale. This method should help to understand the routes taken by prehistoric populations within their environment.

Keywords: Sources, raw material, Prehistory, Protohistory, Maine-et-Loire Department, rocks.