Two perched dune systems are investigated in the Baie d'Audierne (Finistère, Brittany, northwest France). A maximum age of 4545–4160 cal. yrbpfor the onset of sand accretion is provided through radiocarbon (14C) analysis of an organic-rich basal palaeosol, corresponding closely to deceleration, but before stabilisation, of regional Holocene relative sea levels (RSLs). Molluscan analysis through the dune sand indicates an initial bare sand or sparsely vegetated surface, subsequently maturing and colonised by scrub vegetation, and finally returning to more open dune grassland conditions. These data suggest a three-stage Perched Dune Development Model (PDDM), which may be applicable to perched dunes on at least a regional scale: (1) initial sand sheet inundation as RSL rises; (2) stabilisation of RSL allowing dune to mature; and (3) sea-level stabilisation stimulates cliff formation, perching and progressive landward retreat of the dune shore. This study recognises that perched dunes hold greater potential for establishing chronologies for regional Holocene dune development than the more widely studied lowland dune systems, where evidence for early sand inundation may be obscured or lost by modest rises in sea level.
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Document Type: Research Article
School of Geography and Development Studies, Bath Spa University College, Bath, UK,
School of Biological and Environmental Sciences, Bath Spa University College, Bath, UK,
Faculty of Applied Sciences, Bath Spa University College, Bath, UK
Publication date: 2000-04-01