The development, since 2010, of a research project on the Mesolithic of the Sado valley has provided new insights into the study of the lithic technology of the last hunter-gatherer societies. The new excavations carried out at Poças de São Bento shell midden, one of the largest and richest sites identified in the Sado valley, include a protocol for the systematic recovery and recording of archaeological remains, including the water sieving of all the excavated sediments. Therefore, as the new lithic materials do not suffer from any excavation or previous selection bias, it is possible to characterize raw material resources, lithic reduction strategies, tool production and functional areas in a more reliable approach. Selecting a specific excavation area and two different stratigraphic units for analyses allowed us to evaluate site integrity and to test some conventional interpretations concerning tool production and discard. Besides the common lithic blanks (flakes and bladelets) and tools (geometric armatures) already known from previous archaeological works, the analysed sample showed an unsuspected amount of non-characteristic debris, which was underrepresented in the collections of the 1950s, 1960s and even the 1980s. This fact is not exclusively related to the applied recovery methods; it also relates to the existence of intra-site variability (different functional areas) as recent investigations at the shell midden seem to indicate.info:eu-repo/semantics/publishedVersio
