Holocene coastal changes and human adaptation at the mouth of the Gironde estuary, France (SW France)
ARNAUD-FASSETTA, Gilles
Pôle de recherche pour l'organisation et la diffusion de l'information géographique [PRODIG]
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Pôle de recherche pour l'organisation et la diffusion de l'information géographique [PRODIG]
Langue
en
Communication dans un congrès
Ce document a été publié dans
20th Congress of the International Union for Quaternary Research, 2019-07-25, Dublin (IR).
Résumé en anglais
The North Medoc Peninsula is bordered by the Atlantic Ocean to the west and the Gironde estuary to the east. The coast is formed by sandy beaches, dune barriers, estuarine marshes and intertidal mudflats. This sea-land ...Lire la suite >
The North Medoc Peninsula is bordered by the Atlantic Ocean to the west and the Gironde estuary to the east. The coast is formed by sandy beaches, dune barriers, estuarine marshes and intertidal mudflats. This sea-land interface experienced significant coastal changes during the Holocene.During the last three decades, intense winter storms have unearthed vestigial sedimentary deposits containing numerous archaeological remains on the Amélie beach, located on the coastal side of the Gironde estuary. While threatening those nature/culture dialectic archives, this erosional context paradoxically provides an easy access for paleoenvironment analysis. The interdisciplinary project LITAQ aimed to reconstruct the Holocene and Pleistocene environments and related human settlements in this geographical area. Now ended, this program has initiated a long-lasting collaboration between archaeologists and natural scientists through survey campaigns at the Amélie. Combination of topography, stratigraphy, and radiocarbon/relative dating of the beach and associated dune barrier sediments led to chronostratigraphic reconstructions. Thanks to sedimentological analysis, micropaleontology and geochemistry, depositional environment identification was achieved. In addition, several relative sea levels were produced, following the “sea-level index points” method.The nearly complete Holocene sequence of the Amélie was recognized, infilling the paleochannel of Soulac, a tidal inlet of the Gironde estuary, allowing paleogeographic restitutions of this coastal area. Concomitant with a sea level rise slowdown, the tidal channel infilled with marine and estuarine facies around 5000 BC. Protected by coastal dune barriers, two coastal marsh generations were recorded, between ca. 3000 BC to ca. 1500 BC and between ca. 800 BC to AD 300. Around ca. 1500 and ca. 1000 BC, an episode of marine erosion brought coastal dune ridge breach and enhanced wave penetration inside saltmarshes. From AD 300 to 700, the estuarine marsh was gradually buried by coastal dunes.Systematic spatial and stratigraphic analysis of archaeological remains generated correlations between human settlement and supporting environments. From early Neolithic to Antiquity, our research has allowed a better understanding of the human adaptation to environmental changes through time.Additional cores were performed inside the dune ridge and in the eastern marshes, located at the estuarine side of the channel. Coupled with a database of ancient drillings, this data allowed Soulac channel sequencing. The chronostratigraphic framework clarified the environments succession/expansion and erosion/aggradation phases rhythmicity controlled by interplay between marine, aeolian and fluvial processes with variable intensity within the channel. To better specify climate forcing, regional and interregional analogies were made, using indexes such as CSP, coarse grained sedimentation pulses or aeolian activity/stability phases. Moreover, the existence of high resolution marine cores collected during the program HAMOC in the Bay of Biscay, offshore of the Medoc littoral, gave the opportunity to directly correlate climate/marine changes and coastal responses.< Réduire
Mots clés en anglais
dune, estuary, Holocene, Gironde, human adaptation
Project ANR
Using the world in ancient societies : processes and forms of appropriation of space in Long Time - ANR-10-LABX-0052
Origine
Importé de halUnités de recherche