This paper presents the results of new research in the deposit of Visogliano (Aurisina-Sistiana) in the Karst of Triest. Based upon the sediments and the Micromammiferous associations, an arid environment has now been identified which oscillates between continental prairies and steppes with an evolution toward Alpine grasslands as the temperature increases. The human industry in stratum 13 may be attributed to a final moment of the clactonian tecnique. The few finds in strata 22-23 show analogies to Malagrotta industries near Rome. The deposit may be referred to oscillations of the Riss glacial period in the broad sense.