Origin,chronology and environmental significance of Holocene aeolian and alluvial sands at Blue Mountain,Falkland Islands

Extensive and thick sand accumulations, containing organic-rich horizons, at Blue Mountain, Falkland Islands, are most probably derived from weathering of local bedrock under late Pleistocene periglacial conditions. Weathering and subsequent deflation produced several shallow basins that are now occupied by lakes. Sand morphology, sedimentary structures and site characteristics indicate that the sand deposits are predominantly aeolian, although some alluvial sands are also present. Deflation occurred either before the lakes existed or at times of lower lake levels. Sixteen ¹⁴C dates from organic- rich horizons show that some sand accumulated in the early Holocene or late Pleistocene, but that most is of mid- to late Holocene age. Landscape stability/instability phases were not synchronous between sites and cannot be explained by the regional trends of Holocene climate change. A period of significantly lower lake levels and major aeolian erosion at c. 5000-4500 BP is proposed, but is not supported by regional evidence of greater warmth and/or aridity. More environmental data concerning periods of increased aridity and windiness are required before the relationship between landscape evolution and climatic change can be established.