Ultra-high resolution stable isotopic (delta (super 13) C, delta (super 18) O) records derived from bulk carbonates of Ocean Drilling Program sites 690 (Maud Rise) and 865 (Alison Guyot) allow detailed comparison with foraminiferal records. Bulk carbonate delta (super 18) O trends are not consistent with suggestions that the Palaeocene/Eocene isotope event was caused by outgassing of methane, from methane hydrate, thought to be initiated by warming of bottom waters at the end of the Palaeocene. Our data indicate that the oceans were as warm as at the Palaeocene/Eocene boundary excursion for several hundred thousand years prior to it in the late Palaeocene. Furthermore, there appear to be multiple warm/cold cycles within the excursion suggesting a possible orbital control on the pattern and implying a chronology for the event. Tentative estimates of Palaeocene/Eocene boundary event duration are made based on obliquity cycles.