Holocene forested coastal dunes of different morphology fringe the Atlantic coast of southwest Aquitaine. Infra-red stimulated luminescence (IRSL) dating has been applied to sands from these dunes in the Aquitaine region in order to test the validity of dune-classification theories. The ages obtained from the dunes show three phases of sand invasion and dune development during the late Holocene: 3000-4000 years ago; 900-1300 years ago; 250-550 years ago. The timing of the most recent phase of sand mobilization. as dated by IRSL, is supported by historical maps and records from the fifteenth to the eighteenth centuries AD, showing problems for human settlement in the region and village abandonment due to dune drift. Sand invasion is driven by an increase in frequency of severe storms in the North Atlantic associated with the cooler periods of the ‘Little Ice Age’ and early 'Mediaeval Warm Period'. The dunes emplaced 900-1300 years ago were naturally fixed by a mixed deciduous and maritime pine forest during the latter part of the 'Mediaeval Warm Period'.

Archaeological investigations undertaken along a proposed highway together with the compilation of available geological and pedological data made it possible to give a first overview of the distribution of Pleistocene aeolian deposits in southwest France. A chronological framework for deposition has been obtained using both radiocarbon (n ¼ 24) and luminescence (n ¼ 26) dating. It shows that aeolian transport was very active during the Late Pleniglacial, between 15 and $23 ka, leading to sand emplacement over a 13 000-m 2 area at the centre of the basin. The Pleniglacial coversands are typified by extensive fields of small transverse to barchanoid ridges giving way to sandsheets to the east. Subsequent aeolian phases, at ca. 12 ka (Younger Dryas) and 0.8-0.2 ka (Little Ice Age), correspond to the formation of more localized and higher, mainly parabolic dunes. At the southern and eastern margins of the coversand area, aeolian dust accumulated to form loess deposits, the thickness of which reaches $3 m on the plateaus. Luminescence dates together with interglacial-ranking palaeoluvisols between the loess units clearly indicate that these accumulations built up during the last two glacial-interglacial cycles. The chronology of sand and loess deposition thus appears to be consistent with that already documented for northern Europe. This suggests that it was driven by global climate changes in the northern hemisphere. The relatively thin aeolian deposits (and particularly loess) in south-west France is thought to reflect both a supply-limited system and a moister climate than in more northern and continental regions.

The Gironde mud fields are thin blankets (< 4 m) that extend from the inner to mid-shelf over a restricted area (600 km 2 ) and overlie palimpsest sands and gravels seaward of the modern Gironde estuary, south-western France. The bulk of the mud has accumulated over the last two millennia and reflects the complex interactions of: (1) an increasing estuarine supply of suspended particulate matter; (2) resuspension of substrate material by storm events; and (3) biological mixing. The combination of these processes has produced various features within the deposits, related to: (1) the water depth and distance from source of the fine-grained material, which are manifested as a proximal-distal cross-shelf trend, from an area of alternating mud sedimentation (temporary after large river flows) with resuspension by storm events to an area of mud accumulation in deeper water where bioturbation predominates; (2) expansions of the mud depocentres over time, such that they become more remote from sources of coarser shelf sediment, resulting in an upward-fining trend. The lithofacies of the Gironde shelf mud fields exhibit a number of similarities to those of larger scale modern muddy shelves and ancient shallow-water mudrocks; this work provides a detailed description of a facies model for fine-grained shelf sediments deposited under relatively constant sea level.

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