DURING the late Cainozoic, alternations between interglacial and glacial conditions, manifested by waning and waxing of continental ice sheets coincided with the rise and fall of seawater temperatures. Our palaeontological and oxygen isotope data indicate that although the major oceans and low latititude seas underwent large temperature variations, ??? 5-10 ??C, Arctic water temperatures remained near freezing point for at least the past 3 Myr, the time interval represented by the longest studied cores. We have determined palaeotemperatures from the ratio of left to right coiling Globigerina pachyderma1-3 and calculated palaeosalinities using the oxygen isotope palaeotemperature expression of Epstein et al.4. ?? 1975 Nature Publishing Group.