[1] The global warming observed in recent decades and its future increase may affect permafrost distribution on highmountain faces with consequences for their stability. In this paper, we show that rock falls from high-alpine rock walls can be computed with a decimetre-resolution using lidar measurements. A laser scanner was used to create point clouds and triangulated irregular network models on the east face of the Tour Ronde at 3792 m asl (Mont Blanc massif).Comparison of the models realised from measurements of July 2005 and July 2006 enabled quantification of rock falls with reduced uncertainty. The volume of rock fall reached a total of 536 m 3 in the scanned area, which matches an erosion rate of 8.4 mm yr À1 . This rate slightly higher to the ones reported in former studies enable to assume that this rock fall may be the consequence of the permafrost degradation in this rock face. Citation: Rabatel, A., P. Deline, S. Jaillet, and L. Ravanel (2008), Rock falls in high-alpine rock walls quantified by terrestrial lidar measurements: A case study in the Mont

Since its discovery, the Chauvet cave elaborate artwork called into question our understanding of Palaeolithic art evolution and challenged traditional chronological benchmarks [Valladas H et al. (2001) Nature 413:419-479]. Chronological approaches revealing human presences in the cavity during the Aurignacian and the Gravettian are indeed still debated on the basis of stylistic criteria [Pettitt P (2008) J Hum Evol 55:908-917]. The presented 36 Cl Cosmic Ray Exposure ages demonstrate that the cliff overhanging the Chauvet cave has collapsed several times since 29 ka until the sealing of the cavity entrance prohibited access to the cave at least 21 ka ago. Remarkably agreeing with the radiocarbon dates of the human and animal occupancy, this study confirms that the Chauvet cave paintings are the oldest and the most elaborate ever discovered, challenging our current knowledge of human cognitive evolution.absolute dating | cosmonuclide | remote sensing | rockart | rockfall C hauvet cave, in Vallon Pont d'Arc, Ardèche, France, is a site of exceptional scientific interest for a number of reasons: (i) the variety of its majestic parietal; (ii) very good conservation of the floor and wall ornamentations, exhibiting human and animal imprints; (iii) revelations of unknown techniques in Palaeolithic rock art (such as stump drawing); (iv) predominance of rare themes such as felines and rhinoceroses; and (v) unequalled aesthetic delivery (1). On the basis of stylistic comparison with known elements, the Chauvet cave rock ornamentations were initially estimated as being Solutrean (22-17 ka BP) and Magdalenian (17-10 ka BP) (2). The first radiocarbon dates ranging from approximately 30 to approximately 32 14 C ka BP (3, 4) thus disagreed with stylistic analyses such as formalized by Leroi-Gouran (5). Although currently confirmed by 82 radiocarbon dating (6, 7), by crossing dating methods (8,9), and supported by the recent discovery of manifestations of sophisticated Aurignacian prehistoric art (40-28 ka BP) in the Swabian Jura (10), it still remains unclear whether the current stylistic framework should be abandoned in favor of radiocarbon chronologies. Additional robust chronological constraints are therefore critical in establishing Chauvet cave as a reliable benchmark in the absence of comparable equivalent (1,11,12). If corroborated by an independent method, the absolute chronological framework of the Chauvet drawings will indeed establish them as the oldest and most elaborate Aurignacian paintings ever discovered. This will furthermore confirm the existence of an already extremely mature art at that time period during which only few elaborate engraving are known (10), but no other paintings (13,14). To fill this knowledge gap, a geomorphological study combined with 36 Cl dating of rockslide surfaces overhanging the cave entrance was conducted. The Chauvet Cave ClosureGeomorphological studies carried out at Chauvet cave during the last 10 y have unambiguously demonstrated that only one entrance to the cave existed at t...

Rock glaciers result from the long-term creeping of ice-rich permafrost along mountain slopes. Under warming conditions, deformation is expected to increase, and potential destabilization of those landforms may lead to hazardous phenomena. Monitoring the kinematics of rock glaciers at fine spatial resolution is required to better understand at which rate, where and how they deform. We present here the results of several years of in situ surveys carried out between 2005 and 2015 on the Laurichard rock glacier, an active rock glacier located in the French Alps. Repeated terrestrial laser-scanning (TLS) together with aerial laser-scanning (ALS) and structure-from-motion-multi-view-stereophotogrammetry (SFM-MVS) were used to accurately quantify surface displacement of the Laurichard rock glacier at interannual and pluri-annual scales. Six very high-resolution digital elevation models (DEMs, pixel size <50 cm) of the rock glacier surface were generated, and their respective quality was assessed. The relative horizontal position accuracy (XY) of the individual DEMs is in general less than 2 cm with a co-registration error on stable areas ranging from 20-50 cm. The vertical accuracy is around 20 cm. The direction and amplitude of surface displacements computed between DEMs are very consistent with independent geodetic field measurements (e.g., DGPS). Using these datasets, local patterns of the Laurichard rock glacier kinematics were quantified, pointing out specific internal (rheological) and external (bed topography) controls. The evolution of the surface velocity shows few changes on the rock glacier's snout for the first years of the observed period, followed by a major acceleration between 2012 and 2015 affecting the upper part of the tongue and the snout.