Acheulian flint quarries in the Madrid Tertiary basin, central Iberian Peninsula: First data obtained from geoarchaeological studies

Abstract

New investigations carried out over the last few years in the Madrid Tertiary basin have revealed a large number of Acheulean sites used for the exploitation of flint. The find is significantly important because it adds context to the understanding of the intense human activity in the central parts of the Iberian Peninsula during the middle Pleistocene. The sites are spread across an extensive zone of 500 ha; Set on a vast platform on the watershed between the Manzanares and Jarama rivers. The Tertiary sedimentary succession that forms the surface of the platform is comprised of about 20 m of thick green clay interbedded with several layers of flint from the Miocene Intermediate unit of the Madrid basin.During the second half of the Middle Pleistocene, seasonal flows of streams eroded the clay, leaving large numbers of flint nodules visible to the hominids. Investigations show a sustained period of active quarrying, with much of the liberated material converted into hand crafted flint axes (Through the direct manipulation of the flint nodules). The find is valuable especially due to STI exceptional state of preservation; fossilized by sandy fluvial deposits, whose sedimentation is controlled by complex localised subsidences caused by karstic processes.The current study provides geoarchaeological background and explores different models for the formation of the sites and provides a preliminary analysis of the main Acheulean assemblages and techniques for working flint nodules. The research also adds a new, rich perspective to our understanding of the region and the organized human exploitation of raw materials in the Acheulean period. The study complements the well-known river terrace sites in the wider area showing the intensity and prevalence of flint extraction and use during the period, and the handaxe tradition typology of the Madrid region (Pérez de Barradas, 1924, 1929; Santonja et al., 1980; Rus y Querol, 1981; Rus y Vega, 1984; VVAA, 2002; Baena et al., 2010).