Quaternary Science Reviews 25 (2006) 2937–2963 Late Pleistocene and Holocene glaciation in the Pyrenees: a critical review and new evidence from 10 Be exposure ages, south-central Pyrenees Raimon Palla`s a,Ã ,A ´ ngel Rode´s a , Re´gis Braucher b , Julien Carcaillet b , Maria Ortun˜o a , Jaume Bordonau a , Didier Bourle`s b , Joan Manuel Vilaplana a , Eula`lia Masana a , Pere Santanach a a RISKNAT Group, Departament de Geodina`mica i Geofı´sica, Facultat de Geologia, Universitat de Barcelona, Zona Universita`ria de Pedralbes, 08028 Barcelona, Spain b CEREGE UMR 6635, Plateau de l’Arbois 13545, Aix en Provence, France Received 15 May 2005; accepted 20 April 2006 Abstract A compilation and a critical assessment of the 14 C data set available show that the chronology of glacial events in the Pyrenees is not well constrained. After reviewing the literature on glacial reconstruction, we suggest a simplified subdivision of the Pyrenean last glacial cycle record into Last Pleniglacial, Deglaciation, and Neoglacial. To improve the numerical glacial chronology, we provide 10 Be surface exposure ages for 5 glacial erosion surfaces, 9 moraines and 2 erratics in the Upper Noguera Ribagorc - ana Valley (south-central Pyrenees). Published corrected 14 C data and new 10 Be exposure ages indicate that the major phase of moraine building recorded in this valley during the Last Pleniglacial probably occurred after 25 ka BP. This age calls in question the generally accepted hypothesis of a very early deglaciation of the Pyrenees ca 70–40 ka BP, and strongly suggests that the Pyrenees could have been in pleniglacial conditions during the Last Glacial Maximum (LGM). However, we do not exclude the possibility that the maximum glacier extent during the last glacial cycle had taken place much earlier than the LGM, as indicated by some published U-Th, AMS 14 C and OSL data. We suggest that pleniglacial conditions could have taken place during a longer (b30–20 ka) period than generally assumed, and that the Last Pleniglacial could include several glacier fluctuations recorded irregularly in different valleys, with a last major glacier readvance taking place around the LGM. In addition, the Deglaciation is represented by a series of moraines deposited between ca 13.770.9 and 10.170.6 ka. This moraine series indicates a highly variable climatic pattern that is partly correlated with Greenland Stadial 1 (the Younger Dryas), and suggests that the Deglaciation could have continued into the early Holocene. r 2006 Elsevier Ltd. All rights reserved. 1. Introduction The complex oceanographic, atmospheric and glacial system in the North Atlantic region is considered to have played a significant role in the rapid and global climate fluctuations experienced during the late Quaternary (e.g. Alley and Clark, 1999). Recent studies clearly demonstrate that the Iberian Peninsula and surrounding offshore areas are highly sensitive to the variability of the North Atlantic system (e.g. Pe´rez Obiol and Julia` , 1994; Cacho et al., 1999, 2000, 2001; Sa´nchez Gon˜i et al., 2000, 2002; Combourieu Nebout et al., 2002; Moreno et al., 2002). The Pyrenees are located in the north of the Iberian Peninsula, between the Atlantic and the Mediterranean. In this context, the Pyrenean glacial record is a potential source of relevant paleoclimatic data. Despite its relatively low resolution, when correlated and combined with other marine or terrestrial paleoclimate proxies, the glacial record of mountain areas may provide additional constraints on regional precipitation patterns, atmospheric temperature, and on predominant wind regimes. Current knowledge of the Pyrenean glacial record is based on numerous local geomorphological and sedimentological ARTICLE IN PRESS 0277-3791/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.quascirev.2006.04.004 Ã Corresponding author. Tel.: +34 93 403 59 13; fax: +34 93 402 13 40. E-mail address: raimonpallas@ub.edu (R. Palla`s).