| Summary: | Late-glacial to Holocene alluvial deposits have been discovered along a small tributary of the Dordogne river at “La Brunetière” near Bergerac (Dordogne, southwestern France) and yield novel information on the evolution of rivers at the end of the Weichselian. The deposits show that the main alluvial changes described in Northern Europe occurred simultaneously at “La Brunetière”. Two major phases of channel incision in the basal Pleniglacial gravel body have been identified. The first channels developed at the very onset of the Bølling, i.e. before 12,700 ± 45 BP, in a steppic landscape. Rapid channel abandonment allowed development of a small lake, filled in with alternating peat and clay layers rich in vegetal debris. Pollen data as well as molluscs and insects point to an open Artemisia steppe with juniper trees, together with a local component of riparian shrubs (willow and dwarf birch). Palaeotemperatures reconstructed from coleopteran assemblages indicate larger-than-today yearly thermal amplitude with cold winters and warm summers. The lacustrine clays and peats are buried by sandy overbank deposits that are attributed to the Older and/or the Upper Dryas. Channel drying and subsequent hydromorphic soil development relate respectively to the Allerød or the early Holocene. The second phase of incision corresponds to the Preboreal and is typified by stable anastomosed channel formation. Most of these were abandoned during the Boreal and filled by organicclay. An Upper Magdalenian lithic industry has been discovered in a paleosol on the bank of the Late-glacial channel. It includes ca. 200 flakes and 800 small debris of local Maestrichtian flint, and only 15 full-debitage blades and 6 tools. Exclusive use of soft hammer, laminar core morphology, straightness of the small blades, and the 2 pointed blades indicate an ultimate stage of the Upper Magdalenian. Des dépôts alluviaux datant du Tardiglaciaire et du début de l’Holocène ont été découverts dans la plaine du Caudeau, petit affluent de la Dordogne, à La ...
|
|---|