Oxygen-isotope analyses of the benthic foraminiferal species Uvigerina peregrina show that glacially induced changes in the isotopic composition of sea water reached a maximum of 1.5‰ in late Pleistocene time in Tanner Basin, southern California. Isotopic data derived from the planktonic species Globigerina quinqueloba, corrected for glacial and regional water-mass effects, indicates that an increase in mean surface-water temperatures of about 5 °C took place from near the end of the Wisconsin glaciation to the Holocene thermal maximum at about 7,500 yr B.P. The isotopic minimum recorded by U. peregrina at about 40,000 yr B.P. is unusually low compared to that found in open-ocean cores.

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