This study utilizes geomorphology, marine sediment data, environmental reconstructions and the Gorham's Cave occupational record during the Middle to Upper Paleolithic transition to illustrate the impacts of climate changes on human population dynamics in the Western Mediterranean. Geomorphologic evolution has been dated and appears to be driven primarily by coastal dune systems, sea-level changes and seismo-tectonic evolution. Continental and marine records are well correlated and used to interpret the Gorham's Cave sequence. Specific focus is given to the three hiatus sections found in Gorham's Cave during Heinrich periods 4, 3 and 2. These time intervals are compared with a wide range of regional geomorphologic, climatic, paleoseismic, faunal and archeological records. Our data compilations indicate that climatic and local geomorphologic changes explain the Homo sapiens spp. occupational hiatuses during Heinrich periods 4 and 3. The last hiatus corresponds to the replacement of Homo neanderthalensis by H. sapiens. Records of dated cave openings, slope breccias and stalactite falls suggest that marked geomorphologic changes, seismic activity and ecological perturbations occurred during the period when Homo replacement took place.