Compte rendu de Tupaia. Le pilote polynésien du capitaine Cook, de Joan Druett

« And then I wrote Tupaia. It's the biography of one of the most fascinating men who ever lived, a Tahitian who was born on spectacular Raiatea »: cette phrase de Joan Druett (Druett, n.d.) donne le ton de la toute première biographie consacrée au Tahu’a, maître-navigateur et arioi Tupaia. Celui-ci embarqua avec Joseph Banks et James Cook en juillet 1769, puis joua un rôle essentiel de navigateur et interprète sur le reste de l’expédition avant sa triste mort un an demi plus tard, des suites ..

Estimation of anisotropy parameters using the P-wave velocities on a cylindrical shale sample

In this paper we present a new approach to the estimation of the Thomsen anisotropy parameters and symmetry axis coordinates from the P-wave traveltime measurements on cylindrical shale samples. Using the tomography-style array of transducers, we measure the ultrasonic P-wave ray velocities to estimate the Thomsen anisotropy parameters for a transversely isotropic shale sample. This approach can be used for core samples cut in any direction with regard to the bedding plane, since we make no assumption about the symmetry axis directions and will estimate it simultaneously with the anisotropy parameters. We use the very fast simulated re-annealing to search for the best possible estimate of the model parameters. The methodology was applied to a synthetic model and an anisotropic shale sample

Microseismicity Induced in the Opalinus Clay by a Gallery Excavation in the Mont Terri Underground Rock Laboratory

International audienc

Lapita before Lapita: The Early Story of the Meyer/O’Reilly Watom Island Archaeological Collection

Seventeen years before the first excavation at the archaeological site of Lapita (New Caledonia) in 1952, two men of the cloth met and exchanged artefacts, notes and ideas to produce some of the earliest analyses of what later became known as Lapita pottery. Otto Meyer (1877–1937), a Sacred Heart Missionary stationed on Watom Island, described chance finds of ‘prehistoric pottery’ in 1909, following these with more systematic excavations. Patrick O’Reilly (1900–88), a Marist Father associated with the Musée de l’Homme in Paris, drew on Meyer’s work, his own extensive bibliographical knowledge and his observations during a one-year mission in the region in 1934–5 to present part of the collection in France, laying the ground for further theories. The publication, interpretation and curation of the Meyer/O’Reilly collection represents an exemplary journey through the history of Pacific archaeology and the emergence of the Lapita paradigm. We consider the context of Meyer’s encounter with O’Reilly, the ideas both men advanced in analysing the collection and the site, and how these resonated during the development of Pacific and Lapita archaeology throughout the first half of the 20th centuryThis work was supported by the Australian Research Council (ARC) Laureate Fellowship Project ‘The Collective Biography of Archaeology in the Pacific: A Hidden History’ (CBAP) [grant number FL140100218] and by The Australian National University (ANU)

Frequency-dependent seismic attenuation in shales: experimental results and theoretical analysis

Samples of shales from the Ordovician Bongabinni and Goldwyer source rock formations were recovered from the Canning Basin (Western Australia). Attenuation was experimentally measured on preserved plugs from these formations in the frequency range between 10−2 and 102 Hz. Samples cored with different orientations with respect to the sedimentary bedding were prepared and tested in their native saturated state and after drying in the oven at 105 °C for 24 hr to assess the effect of fluids and of the sediment anisotropy on attenuation. To aid the interpretation of the experimental results, the clay-rich samples were characterized in terms of mineralogy, water content, porosity, permeability and microstructure. The two shales have significantly different quality factors; and this is seen to be dependent on both the saturation state of the samples and the propagation direction of the oscillatory signal. The attenuation coefficient for compression/extension parallel to bedding is less than that vertical to bedding in both the preserved and partially dehydrated situations. No frequency dependency is observed in the preserved samples within the range of frequencies explored in this study. On the other hand partially saturated samples show peaks in attenuation at around 40 Hz when the stress perturbation is transmitted normal to the macroscopic bedding. The interpretation of the attenuation measurements in terms of well-established theoretical models is discussed in view of the physical characteristics and microstructure of the tested rock

The size inherited age effect on radiocarbon dates of alluvial deposits: redating charcoal fragments in a sand-bed stream, Macdonald River, NSW, Australia

Radiocarbon dates on charred plant remains are often used to define the chronology of archives such as lake cores and fluvial sequences. However, charcoal is often older than its depositional context because old-wood can be burnt and a range of transport and storage stages exist between the woodland and stream or lake bed ("inherited age"). In 1978, Blong and Gillespie dated four size fractions of charcoal found floating or saltating in the Macdonald River, Australia. They found larger fragments gave younger age estimates, raising the possibility that taphonomic modifications could help identify the youngest fragments. In 1978 each date required 1000s charcoal fragments. This study returns to a sample from the Macdonald River to date individual charcoal fragments and finds the inherited age may be more than 1700 years (mode 250 years) older than the collection date. Taphonomic factors, e.g., size, shape or fungal infestation cannot identify the youngest fragments. Only two fragments on short-lived materials correctly estimated the date of collection. In SE Australia, this study suggests that wood charcoal will overestimate the age of deposition, taphonomic modifications cannot be used to identify which are youngest, and multiple short-lived materials are required to accurately estimate the deposition age

Archéogéographie et processus de territorialisation pré-contacts au Nord de la Grande Terre (Nouvelle-Calédonie)

L’intérêt porté par l’archéologie calédonienne au dernier millénaire de la chronologie pré-européenne s’est principalement développé avec la création du département Archéologie néo-calédonien au début des années 1990. Toute une série de programmes de terrain spécifiquement axés sur l’archéologie de ce qui a été défini comme l’« ensemble culturel traditionnel kanak » s’est alors mis en place. Progressivement, un ensemble de données et d’analyses préliminaires, portant principalement sur la moitié Nord de la Grande Terre, a commencé à se constituer. À la suite de ces travaux ont été menées des analyses d’archéologie spatiale et de comparaison des données ethnologiques et archéologiques, afin de tenter de définir le mode d’occupation de l’espace et de territorialisation des sociétés kanak pré-contacts dans cette partie de la Nouvelle-Calédonie. Nous présentons ici une synthèse des résultats obtenus.New-Caledonian archaeology mainly started to focus on the last millennium of the pre-European chronology with the creation of the Archaeology Department of New Caledonia, in the early 1990’s. A series of fieldworks specifically investigating what has been labelled « the traditional Kanak cultural complex » were put in place. A set of data and preliminary analyses mainly looking at the northern half of Grande Terre has progressively been constituted. Building on these studies, spatial analyses and comparisons of archaeological and ethnographical data were realised in order to define the territorial system and spatial occupation patterns of pre-contacts Kanak societies in this region of New Caledonia. This article synthesizes the main results of these studies