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International audience; Despite a wealth of recent studies dealing with the evolution of the drainage network in the uplifted Ardennes massif (E. Belgium), especially from the Middle Pleistocene onwards, the Ardennian landscape evolution and long-term incision rates in the Meuse catchment remain poorly documented over the whole Plio-Quaternary. Alluvium-filled multilevel cave systems represent a relevant setting to unravel the Late Cenozoic history of regional river incision. We present here a dataset of 26 Al/ 10 Be concentration data obtained from fifteen pebble samples washed into the Chawresse system, one of the largest multi-level cave systems of Belgium, which developed in Devonian limestones of the lower Ourthe Valley, the main Ardennian tributary of the Meuse. The sample collection spans an elevation difference higher than 120 m and their depleted 26Al/10Be ratios yield burial ages ranging from ~0.25 to 3.28 Ma. After critical assessment of our dataset for intra-karstic reworking issues, the most striking outcome of the obtained burial ages is the acceleration by a factor five of the incision rates (from ~30to ~150 m/Ma) during the first half of the Middle Pleistocene. Integrating this incision peak and our pre-burial denudation rates, we then revisit the existing framework of Plio-Quaternary denudation and river incision in the Ardennian Meuse catchment. Whilst our 26Al/10Be concentration data shed new light on the temporal andspatial variability of the local river and hillslope system response to coupled tectonic and climatic forcings, it simultaneously highlights sampling issues and the need for further chronological data.

Cussac Cave is well-known for its spectacular engraved art and well-preserved human remains attributed to the Gravettian period of the Upper Paleolithic, but it also contains many lesser-known remains and traces of human and animal presence throughout the site. Since 2009, a team incorporated in the Projet Collectif de Recherche “Grotte de Cussac”, directed by J. Jaubert, has been engaged in the identification, inventory and study of these “Activity Traces” (TrAcs). The objective is to study the interactions of humans and animals with this subterranean environment and to understand how humans perceived this complex space. Our aim is to confront the data associated with these TrAcs with the information provided by other disciplines. This approach is made possible by the conditions of the discovery of the cave, which was left almost untouched since the Paleolithic, and the strict policy of conservation that has been implemented. The team explores the cave in a non-invasive manner, respecting the limits of a designated pathway while recording, describing, and photographing the accessible TrAcs. The areas that are currently inventoried show that human TrAcs are more frequent and diverse than those of animals, and consist mostly of prints, tracked surfaces and black and red marks. Most of the animal TrAcs were produced by bears, and consist mainly of claw marks covering large areas. These bear marks always predate the human activities. The presence of TrAcs, art and human remains shows that this entire subterranean environment was intensively frequented by both humans and bears. Our approach constitutes a fundamental step towards an understanding of the cave, and more generally, of the identity and culture of Gravettian groups, reflected here in their behavior, activities and occupations in the context of this complex site with monumental engravings and human remains.