Search

A multi-proxy environmental record for the Devensian (Weichselian) Lateglacial and early Holocene periods, which includes pollen, plant macrofossil, coleopteran, geochemical and stable-isotope data, is described from a site at Llanilid, South Wales, UK. The geochronology of the sequence is derived from two age–depth models which show a broad measure of agreement over much of the profile. This data set provides the basis for a detailed reconstruction of changing environmental conditions in western Britain during the transition from the Last Cold Stage to the present (Holocene) interglacial (ca 15,000–10,000 cal yr BP). Two marked cooling episodes are recorded during the course of the Lateglacial Interstadial (Greenland Interstadial 1), with mean July temperatures falling by more than 5°C from a maximum of around 20°C during the early Interstadial, and by a further 4–5°C around 13,100 cal yr BP. The initial drop in temperature led to a reduction in Juniperus scrub, while the second, and more abrupt temperature decline resulted in a significant contraction in areas of Betula woodland. A relatively slight and short-lived warming during the later Interstadial enabled tree birch to expand once again. Mean July temperatures of 10–11°C characterised the Loch Lomond/Younger Dryas Stadial (Greenland Stadial 1) between ca 12,600 and 11,400 cal yr BP, during which time a scrub tundra with Betula, Salix and a range of open-habitat taxa became established locally. The onset of the Holocene Interglacial at ca 11,400 cal yr BP is marked by an abrupt temperature rise of the order of 9°C, and by the rapid expansion of Betula woodland. The Llanilid palaeoclimate record is similar to that from the Gransmoor site in northeast England, and also to the climatic sequence inferred from the GRIP ice core, particularly during the later part of the Lateglacial Interstadial (ca 14,000–12,600 cal yr BP), during the Loch Lomond/Younger Dryas Stadial and in the early Holocene. The Llanilid chronology is less secure during the early part of the Lateglacial Interstadial (pre-14,000 cal yr BP), but it is possible that warming may have begun earlier in this part of western Britain than in Greenland. [Copyright &y& Elsevier]

Abstract: The North Atlantic INTIMATE group of the INQUA Palaeoclimate Commission has previously recommended an Event Stratigraphy approach for the synchronisation of records of the Last Termination using the Greenland GRIP isotopic record as the regional stratotype and INTCAL98 for the calibration of radiocarbon dates [Lowe, J.J., Hoek, W., INTIMATE Group, 2001. Inter-regional correlation of palaeoclimatic records for the Last Glacial-Interglacial Transition: a protocol for improved precision recommended by the INTIMATE project group. Quaternary Science Reviews 20, 1175–1187]. Here, we present a revised protocol for time-stratigraphic correlation in the North Atlantic region over a more extended time period (30–8ka). This employs the new NGRIP isotopic record and associated Greenland Ice Core Chronology 2005 (GICC05) as the regional stratotype, INTCAL04 for the calibration of radiocarbon dates, Bayesian-based statistical procedures for the construction of age models, and tephrochronology to validate correlations between regional site records. [Copyright &y& Elsevier]