The Pleistocene Faro/Quarteira formation of the Algarve region, southern Portugal

The quartzite dominated Faro/Quarteira formation covers a large proportion of the coastal lowlands of the Algarve, southern Portugal. The formation has been the subject of considerable controversy in the literature and ages ranging from the late Miocene to the late Pleistocene have been proposed, while its mode of origin has been variously ascribed to fluvial, aeolian and marine processes. In this paper the geomorphology of the formation is described and this information, together with that gleaned from the study of sections, has not only allowed a model of emplacement to be proposed, but has also cast light on its likely age of deposition. We conclude that the Faro/Quarteira formation was deposited by a combination of fluvial and debris flow activity and that it represents a glacis or mountain foot accumulation eroded from the interior of the Algarve. Sediment sources include: soils; weathered bedrock and possible deposits from reworked former raised shorelines. A contribution of aeolian sediment in the later stages of development is also probable. By means of a combination of field mapping, archaeological evidence and relationships with other dated Quaternary formations, a late Pleistocene date seems most likely, with sedimentation ending between ∼ 35,000 and ∼ 40,000 BP.