PLEISTOCENE AND HOLOCENE HUNTER-GATHERERS IN IBERIA AND THE GIBRALTAR STRAIT: THE CURRENT ARCHAEOLOGICAL RECORD 584 cavation work over the next few years, we will undoubtedly be able to extend the time frame represented at the Pinilla del Valle sites and in- crease the archaeological and paleobiological re- cord, thereby helping to enhance our knowledge of this chronological period in the centre of the Iberian Peninsula. Acknowledgments This study has been conducted in the frame- work of the S2010/BMD-2330 project funded by the R and D activity programme for research groups of the Ministry of Education, Youth and Sports of the Autonomous Community of Madrid. We are grateful to the Ministry of Employment, Tourism and Culture of the Autonomous Com- munity of Madrid for the funding. The General Foundation of the University of Alcalá executes financial management of the project. The authors would also like to thank Mahou-San Miguel S.A. for its work as sponsor, and to the Peñalara Nature Reserve, Pinilla del Valle Town Hall and Canal de Isabel II for their collaboration. .Finally, we would like to thank the Pinilla del Valle excavation team for its work, without which this publication would not have been possible. San Quirce (Palencia, Spain), a Middle Paleolithic site on the northern plateau Marcos Terradillos-Bernal*,**, J. Carlos Díez Fernández-Lomana*, Jesús-Francisco Jordá Pardo***, Alfonso Benito-Calvo****, Ignacio Clemente*****, Alexandra Hilgers****** 1. Introduction and Background Surveys were conducted in the 1980s and 1990s to identify prehistoric occupations in the middle reaches of the Pisuerga River between Alar del Rey and Astudillo (Palencia) (Arnaíz, 1990), which re- sulted in the recovery of many Paleolithic series. San Quirce was the only excavated site. It was discovered during the preparation of a gravel pit. The terrace was cut and three profiles were sur- veyed, measuring 35 m (east) and 40 m (north). Excavation was conducted in two areas, with 19,537 lithic artefacts recovered along with two small hearths attributed to the Acheulean period (Arnaíz, 1996). The current research team resumed the exca- vations in 2009 in the context of a new survey and research project in the Pisuerga River valley. To date there have been three excavations. 2. Context The San Quirce Paleolithic site is located in the extreme north of the Duero Basin (UTM: X = 392.828, Y = 4.720.122, Z = 861 m. us- ing H30N, reference system ETRS89) on a river terrace +22- 23 m (T9). The context is of great interest since it is located in a strategic contact area between the Cantabrian Mountains and the Northern Plateau. Terrace T9 consists of gravel bars and a clay matrix, mostly by illuviation. Four major stratigraphic units were identified: Colluvium (I), colluvium (II), floodplain at the distal end of an alluvial fan (III) and river terrace deposits (IV) (Fig. 1). We have obtained an OSL dating sequence be- tween 74 ± 16 ky in sandy flood deposits (profile E in the quarry and lateral variation of level III) and 154 ± 18 ky in the area excavated on level III * Área de Prehistoria. Universidad de Burgos mterradillos@hotmail.com, clomana@ubu.es ** Fundación Atapuerca *** Dpto. de Prehistoria y Arqueología. Universidad Nacional de Educación a Distancia **** Centro Nacional de Investigación sobre evolución Humana (CENIEH) ***** Institució Milà i Fontanals-CSIC ****** Institute of Geography – University of Cologne