On knapping pebbles. Impact of pebble morphologies on debitage initialisation and differences with ramification processes.

International audienceIn numerous archaeological sites, pebbles/cobbles from alluvial deposits constitute a major source of raw materials procurement. It concerns various mineral environments, with diverse raw material types and modules (flints, quartz, quartzites, volcanic rocks, etc.). In these sites, we notice that the anvil split is frequently used to initiate knapping reduction processes. The pebble morphologies (elongated, thin, spheric) and their dimensions can have a strong impact on knapping processes applied, in particular during the initialisation phase, both for flaking and, more rarely, shaping processes. Thus in numerous lithic assemblages pebbles are splitted in two parts, used subsequently as blanks for flaking/shaping. This (or these) split is made most of the time by bipolar-on-anvil percussion. The two products can’t be assigned in classic categorisation, as there is no real core/real flake. In the caseof flaking reduction processes, the result is the production of a plano-convex blank, half cortical, that can present often the flake morphology and thus present strong affinities with flaked-flakes. However, this kind of technical process has to be distinguished from ramification processes, even if the presence of one does not exclude the other.In this presentation, we will consider several sites from the Early Middle Palaeolithic/Late Middle Palaeolithic to discuss these techno-economic implications. In the involved sites, pebbles constitute the main modules of raw materials used or an additional source (Languedoc, Pyrenees-Garonne region, and northern Aquitaine Basin). They are located both in flint and non-flint environments. All were subject to detailed technological analysis in order to identify the main chaînes opératoires and the production objectives