Ocean sediment data - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 178

Figure 5.3. Universality of oxygen isotope patterns from forams from around the world
(adapted from M&M with permission of Praxis Publishing).
location was constant and that time scales were chosen for each such that the ice
age terminations (vertical dashed lines) occurred at roughly the same times. The
fact that the terminations do not line up precisely with each other suggests that
sedimentation was not perfectly constant for each record. M&M felt it remarkable
that the pattern of oxygen isotope variations appears to be so similar around the
world. It is noteworthy that the terminations of ice ages often appear to be
abrupt.
5.4 SUMMARY OF OCEAN SEDIMENT ICE VOLUME DATA
An influential early attempt to extract the underlying 18 O signal from multiple
records was the SPECMAP Stack (Imbrie et al. 1984; M&M). The ''stack'' was a
combination of five 18 O records from five cores from the Indian, Atlantic, and
Pacific Oceans. M&M pointed out: ''although the time scale for this stack is now
known to contain serious errors in the period older than 600 kybp it is still a
widely-used template for more recent times.'' Each interglacial period is allocated
an odd number, beginning with the present as Stage 1 and counting backwards.