LATE PLEISTOCENE SEDIMENTS AND ENVIRONMENTAL-CHANGE AT PLAZA CREEK, FALKLAND ISLANDS, SOUTH ATLANTIC

Late Pleistocene organic-rich sediments exposed in coastal bluffs near the head of Plaza Creek, East Falkland, have yielded conventional and AMS C-14 dates of between 36 and 28 ka BP, and possess a pollen spect rum dominated by grasses, indicating a vegetation assemblage similar t o that of the present day. Although some sample dates are anomalous an d contamination by non-contemporaneous carbon cannot be ruled out enti rely, the age estimates are consistent with evidence and dates from An tarctica, South America and the amphi-North Atlantic for climate shift s to interstadial conditions at around that time. The organic-rich uni ts are developed in and enclosed by deposits attributed to processes o f periglacial mass wasting. Grain-size characteristics suggest that th ese sediments may have been emplaced by solifluction, shallow translat ional landsliding and surface wash in at least five mass-wasting episo des. Some of the mass-wasting sediments might correlate with solifluct ion deposits above and below a podsolic soil dated to 26 ka BP at San Carlos, East Falkland, and with periods of cirque and valley glaciatio n identified in the uplands of the Falkland Islands. The similarity be tween late Pleistocene interstadial, Holocene and present-day pollen a ssemblages, and the lack of vegetation change within these periods, is characteristic of most cool temperate Southern Ocean islands, and may reflect the lack of sensitivity of the vegetation to climate change a nd/or a lack of climate variability for the time intervals covered. (C ) 1998 John Wiley & Sons, Ltd.