Dugout Canoes from Lakes of the Adirondack Uplands

We describe here four dugout canoes that have been retrieved from three water bodies in the Adirondack uplands during the last half century. Two dugouts from Lake Placid and Lake Ozonia, which are kept at the Six Nations Iroquois Cultural Center and Adirondack Experience, respectively, were made by Indigenous or Euro-American people equipped with metal tools and are probably no more than 4 centuries old. Two other dugouts under private ownership that were retrieved from Twin Ponds were almost certainly made by Indigenous artisans with traditional methods. The larger of the two is 6 m long and up to 5 centuries old, possibly the oldest boat known thus far from the Adirondack uplands. All of these dugouts were probably built, used, and stored at the lakes they were found in. The great size and weight of the larger Twin Ponds dugout in particular suggests long-term use at the discovery site and therefore challenges persistent claims that Indigenous people did not live in the Adirondack uplands

Paleolimnological evidence for the onset and termination of glacial aridity from Lake Tanganyika, Tropical East Africa

International audienceGeochemical and sedimentological data in a continuous 60,000-year sediment core record from the Kalya horst region of central Lake Tanganyika provide a detailed history of paleoclimate-mediated weathering and overflow events from upstream Lake Kivu. Univariate (elemental profiles), bivariate (elemental ratios) and multivariate analyses of chemical trends show variations between the dry Late Pleistocene (32­18 ka cal yr BP) and the wetter conditions that both preceded and post-date that interval. This record places important new constraints on the timing of aridity in East Africa during the high-latitude Last Glacial Maximum (LGM) based on significant decreases in magnetic susceptibility and soluble cation concentrations coinciding with biogenic silica. Elemental indicators in the oldest portion of the sedimentary record (60­50 ka cal yr BP) characterize this interval as a comparatively wet period, similar to modern conditions. Our record demonstrates that the ensuing transition toward arid conditions in tropical Africa during high-latitude glaciation was a two staged event with intermediate levels of aridity occurring from 50­32 ka cal yr BP followed by intense aridity from 32­18 ka cal yr BP. The initiation of inflow from upstream Lake Kivu into Lake Tanganyika is evidenced at 10.6 ka cal yr BP through its influence on both elemental profiles (Mg, Ca) and through its effect on 87Sr/86Sr. Increases in elemental (Mg, Ca, Sr) concentrations coincide with the timing of the Lake Kivu overflow. Metal geochemistry suggests that the overflow from Lake Kivu into Lake Tanganyika may have ceased between 8 and 6 ka cal yr BP, suggesting a period of Middle Holocene aridity in East Africa