Gérard Vernet

TEPHROSTRATIGRAPHY OF THE LAST 160 ka IN WESTERN LIMAGNE (FRANCE)

The GEOCLER 1 core extracted from the Clermont crater lake sediments and surface studies made at several localities north of Clermont provided numerous stratigraphic, environmental and chronological data (TL and radiocarbon) which allow us to present a chronostratigraphy of the Limagne for the past 160 ka. 118 ash-falls have been recorded in the crater-lake sediments of the Clermont maar. They demonstrate that a basaltic phreatic activity developed along the western fault-scarp of the Limagne between 160 and 70 ka, after which began the Chaine des Puys activity. Moreover, several acid eruptions occured between 160 and 40 ka. From Older Dryas to Atlantic, between 15 and 7 ka, fourteen ash-falls occured and in some cases the source volcanoes have been identified. These include Puy de La Nugere, Puy de Dome, Puy Chopine, Kilian Crater and Puy de Pariou which contribute mainly to the local tephra succession. Prospects for further prehistoric research in volcanic areas are outlined.

Sedimentary Dynamics and Tecto-volcanism in the Venosa Basin (Basilicata, Italia)

Direct tecto-volcanism is the main process involved in the sedimentary filling of the Venosa lacustrine Basin. Two formations have been distinguished : the Tufarelle Formation and the Piano Regio Formation. In the sedimentary series exposed at the Notarchirico Middle Pleistocene prehistoric site, several volcanic episodes represented by pumice falls, coarse and fine ash-falls and subsequent epiclastic processes have interrupted the lacustrine sedimentation and induced specific environmental changes. Hominids were present immediatly after every volcanic event to exploit the new environment on an opportunistic basis.