14C dates and the geological setting of Quaternary marine deposits from three sites in West Greenland indicate a pre-Holocene age. The mollusc faunas at the sites are distinctly different, although all reflect influx of some subarctic water into Baffin Bay. The fauna from Patorfík is the most diverse subfossil Quaternary fauna known from Baffin Bay. Such species as Panopea norvegica and Balanus hameri indicate conditions warmer than the present, although no identical faunal assemblages are known. The fauna at Laksebugt is similar to modern faunas, but the dominating Portlandia arctica and Macoma moësta indicate a climate somewhat colder than the present, and Mytilus edulis suggests the presence of subarctic water. The fauna from Mudderbugt is reworked, but the presence of Chlamys islandica indicates that conditions were not entirely different from the present.Amino-acid analyses on shells from the three sites place them in three distinct aminozones, with Patorfík as the oldest and Laksebugt the youngest. Age estimates using this and geological and biological evidence suggest that the Laksebugt aminozone dates from the isotopic stage 5–6 transition (130 ka). The Patorfík aminozone is probably of mid- or early Quaternary age (235–1800 ka).Correlation with the few previously known pre-Holocene marine deposits of western Greenland implies that only one period of extensive glaciation can be recognized during the Weichsel (Wisconsin) glaciation.