International audienceThe Thomas Quarry I locality was made famous in 1969 with the discovery of a human half-mandible in a cave. In 1985, further investigations revealed the presence of a Lower Acheulean assemblage in lower units of the section. From 1988 onwards, modern controlled excavations took place within the framework of the Franco-Moroccan co-operative project "Casablanca". Acheulean artefacts, a rich mammalian fauna and four hominid teeth have been excavated from the cave. The faunal set indicates an open woodland environment. Carcasses were processed by carnivores, but cut-marks are absent, which raises the question of any human role in the bone accumulations. Stone knapping was mainly oriented towards flake production and a few bifaces have been imported into the site. Laser ablation ICP-MS dating combining the ESR and U-series data for the modelling of the U-uptake has given an US/ESR age of 501 ± 76 ka for a human premolar while new OSL measurements yielded an age of 420 ± 34 ka for sediments immediately above the dated tooth and 391 ± 32 ka below. Nevertheless, biostratigraphy and lithostratigraphy point towards a greater antiquity
Un outillage lithique acheuléen, une riche faune du Pléistocène moyen et quatre dents d'hominidés ont été extraites du remplissage de la cavité de la carrière Thomas I, célèbre depuis la découverte en 1969 d'une hémimandibule humaine. Depuis 1988, des fouilles sont conduites dans ce site dans le cadre du programme franco-marocain «Casablanca ». Une riche faune mammalienne et quelques restes de reptiles et d'oiseaux sont associés à l'industrie lithique dans l'unité stratigraphique 4. La faune, introduite par les carnivores, indique un paysage peu boisé et le stade évolutif des divers taxons suggère un âge plus récent que celui de Tighenif (Algérie). Les marques de découpe sont absentes, ce qui pose la question du rôle des hominidés dans l'accumulation des restes fauniques. Le travail de la pierre était orienté vers la production d'éclats et de rares bifaces ont été introduits dans cette partie du site. Quatre dents humaines ont été exhumées entre 1994 et 2005. La datation ICP-MS par ablation laser combinant l'ESR et les séries de l'Uranium pour modéliser l'enrichissement en Uranium a été appliquée à une prémolaire humaine : elle a fourni un âge de 501 k a. De nouvelles mesures d'âge par OSL sur les sédiments encadrant la dent datée ont respectivement donné 420 ± 34 ka au dessus et 391 ± 32 ka en dessous confirmant un âge minimum centré sur une période relativement ancienne du Pléistocène moyen.
The Mio-Plio-Pleistocene sequence at Casablanca, covering the last six million years, is well known in scientific literature. The variability and the chronology of the Acheulian sequence is documented by systematic, modern and controlled investigations in various sites (Unit L and Hominid Cave at Thomas I Quarry, Rhinoceros Cave at Oulad Hamida 1 Quarry, Sidi Abderrahman Extension Quarry, Bear's Cave and Cap Chatelier at Sidi Abderrahman Quarry) which have taken place within the framework of the Franco-Moroccan co-operative project "Casablanca". In order to manage the excavation data and to explore the taphonomic nature of Unit L, Hominid Cave and Rhinoceros Cave, where research is still in progress, an approach combining a Geographic Information System (GIS) and spatial analysis techniques was developed, incorporating all existing information produced from previous excavations and recent surveys of the sites. The amalgamation of this data into a GIS has resulted in a digital database that allows the production of simultaneous or separate visualizations and analyses of the fossils, artifacts and geological materials within their original spatial contexts and also permits intra-site spatial analyses that allow a comprehensive investigation of the site formation processes.
The onset of the Acheulean, marked by the emergence of large cutting tools (LCTs), is considered a major technological advance in the Early Stone Age and a key turning point in human evolution. The Acheulean originated in East Africa at ~ 1.8–1.6 Ma and is reported in South Africa between ~ 1.6 and > 1.0 Ma. The timing of its appearance and development in North Africa have been poorly known due to the near-absence of well-dated sites in reliable contexts. The ~ 1 Ma stone artefacts of Tighennif (Algeria) and Thomas Quarry I-Unit L (ThI-L) at Casablanca (Morocco) are thus far regarded as documenting the oldest Acheulean in North Africa but whatever the precision of their stratigraphical position, both deserve a better chronology. Here we provide a chronology for ThI-L, based on new magnetostratigraphic and geochemical data. Added to the existing lithostratigraphy of the Casablanca sequence, these results provide the first robust chronostratigraphic framework for the early North African Acheulean and firmly establish its emergence in this part of the continent back at least to ~ 1.3 Ma.
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