Figure 3.
13C values (left panel) and
18O values (right panel) for Globigerinoides ruber (a surface-dwelling planktic foraminifer) plotted against radiocarbon years from ODP 619A in Pigmy Basin, Gulf of Mexico. Figure from Poore and Wright (1999). Simultaneous excursions to smaller
13C values and
18O values are highlighted
by bars at 7000 and 7800 radiocarbon years ago; these excursions reflect influxes of freshwater, which decreased the salinity of the surface-water layer; see text for discussion.