This study presents, firstly, the Nideck surface deposit of rhyolite exploited during the Middle Palaeolithic, its lithology, its outcrop and its stratigraphical context, and then the core reduction pattern and the tools of the lithic artefacts collected. The prehistoric deposit is located on a hillslope. Two areas were defined: an excavation on a subhorizontal bench (Series A) and a survey in the fan- talus (Series B) below the test trench. The stratigraphy is never more than I m high: it shows a humus level and a disturbed one. The substratum consists of a rhyolite plate. Artefacts were found in both stratigraphie levels, they are all knapped from white rhyolite blocks, except one from a red rhyolite block. The morphology of the blocks, more than the raw material quality, has dictated constraints during knapping. Butt preparation is exceptional, and there is little core shaping. The Series A industry shows above all Discoid core reduction with occasional peripheral convexity shaping. A few opportunistic blades are sometimes produced. Side-scrapers are the more numerous tools (about 45%), with no predominating pattern. There are also notches, end-scrapers and partially retouched flakes. Blanks are very variable, with however a preference for thick large ones. The Series В industry also shows lots of Discoid cores, with three patterns imposed by the morphology of the knapped blocks. A blade-specific production appears on some long cores. Both procedures can exist on the same core. More than half the corpus of tools is composed of denticulates and notches. Among scrapers (23% of tools), we find a double angle convergent scraper (" rechtwinkliger Schabe "), and also three end-scrapers using the tranchet technique. Two characteristics found in Nideck industries have parallels all along the Rhine valley: they are the blade production and the double angle convergent scraper. Predominating in the north part of this area, blade production seems to be less important from the Bruche valley up to the north of the Jura mountains. These data help to give a date between the Eemian and the Last Glacial, or isotopic phases 5 and 6, or the Rocourt phase and Period 1 of the Rhenish chronology. The Vosges mountains run along the west side of the Alsace plain. In the southern Vosges, the Bruche valley crosses a big volcano-sedimentary and volcanic complex from the Devono-Dinantian to the Permian age. This axis draws the boundary between the granitic Hercynian and the sandstone Vosges. The Nideck Dale is situated in this geological complex strongly characterised by volcanic activity. The Permian volcanic formations from Nideck are red or white fluidal texture rhyolites, compact and rich in silica. They consist of a quartz and fibrous feldspar microcrystals background including enallogenetic dark purplish-blue inclusions, detritus of rocks and devitrification basin forms with fibroradiated crystallised spherulites. These rocks are involved informations including ignimbrite, tuff, vitreous tuff and volcanic breccia, less siliceous, more heterogeneous and softer: rhyolites are the only type to have been exploited. The rhyolite front appears as little beds 1 or 2 m high and about 10 m wide. It is fissured in prismatic and rhombic blocks with flat sides and acute angles.
Cette étude présente d'une part le gîte de rhyolites du Nideck, exploité au Paléolithique moyen, sa pétrographie, ses modes d'affleurements et son contexte stratigraphique ; d'autre part les schémas de débitage ainsi que l'outillage des séries lithiques récoltées. L'origine, la texture, la structure des matières premières sont d'importance dans cette étude. En effet, le degré de silicification et le format naturel des blocs à l'affleurement, accessibles en prismes réguliers, ont favorisé leur exploitation par l'homme. Le but était de déterminer les secteurs d'approvisionnement et d'étudier les gîtes afin d'établir quels types de blocs ont été recherchés et taillés. Les deux séries étudiées ont ainsi montré des différences dans le choix des blocs ainsi que dans l'organisation des modes opératoires. Quelques outils montrent des traditions communes avec les industries de la vallée du Rhin.
