J. Backman H. Zimmerman D.V. Kent M.A. Hall David G. Roberts D. Schnitker J.G. Baldauf A. Desprairies R. Homrighausen P. Huddlestun J.B. Keene A.J. Kaltenback K.A.O. Krumsiek A.C. Morton J.W. Murray J. Westberg-Smith N. J. Shackleton 1984 We report here that DSDP Site 552A, cored with the hydraulic piston corer on the west flank of Rockall Bank, recovered an undisturbed sequence of alternating white deep-sea carbonate oozes and dark-coloured layers that are rich in glacial debris. Oxygen isotope analysis of the sequence together with detailed nannofossil and palaeomagnetic stratigraphy shows that the first major horizon of ice-rafting occurred at about 2.4 Myr, and was preceded by a minor pulse of ice-rafting at about 2.5 Myr. The carbon isotope record shows that the site has been bathed by a water mass of similar characteristics to present-day North Atlantic deep water at least since 3.5 Myr. ?? 1984 Nature Publishing Group. application/pdf 10.1038/307620a0 en Oxygen isotope calibration of the onset of ice-rafting and history of glaciation in the North Atlantic region article