After a phase of pivotal international role, under the works of Carlos Ribeiro and J.F. Nery Delgado, Portuguese prehistory has become more and more tributary of results obtained in other European countries. This explains why quite often the Palaeolithic of Atlantic western Iberia is interpreted in the framework of Southwest France Karstic sequences, specifically those studied in Dordogne. The absence of certain phases of the "classical sequence" on the Portuguese record has been a recurrent theme of debate in the latest years. This debate has been focusing specifically on the chronology and diffusion modalities of the first upper Palaeolithic "cultures" of the region. The stratigraphic record from the Lower Mondego karstic sequences evidences sedimentary discontinuities taking place at the transition between the final Middle Palaeolithic and the initial Upper Palaeolithic. Recent fieldwork suggests that those erosion discontinuities may explain the observed cultural hiatuses. For this reason, the description of such discontinuities and their rhythm becomes crucial for any discussion concerning the interpretation of archaeological and sedimentary absences. In this paper we evaluate the pedo-sedimentary and archeo-stratigraphic record of several recently excavated karstic sequences from central Portugal. The sites locate on the Condeixa-Sicó-Alvaiázere massif (Buraca Grande, Buraca Escura, Vale das Buracas and Abrigo 1 de Vale de Covões), and on Mondego northern margin (Gândara do Outil 1). After a correlation between sedimentary facies and paleoclimatic inferences based on the observed sequences, the major discontinuities were plotted on a regional chronological framework. The inclusion of the techno-typological characteristics of the lithic assembles from different archeological levels to this sedimentary background permits the elaboration of different scenarios for the explanation of technical and cultural changes between 30.000 and 10.000 BP.
