SEA-SURFACE TEMPERATURE-CHANGES IN THE SOUTHERN CALIFORNIA BORDERLANDS DURING THE LAST GLACIAL-INTERGLACIAL CYCLE

A variety of evidence suggests that average sea surface temperatures ( SSTs) during the last glacial maximum in the California Borderlands re gion were significantly colder than during the Holocene. Planktonic fo raminiferal delta(18)O evidence and average SST estimates derived by t he modern analog technique indicate that temperatures were 6 degrees-1 0 degrees C cooler during the last glacial relative to the present. Th e glacial plankton assemblage is dominated by the planktonic foraminif er Neogloboquadrina pachyderma (sinistral coiling) and the coccolith C occolithus pelagicus, both of which are currently restricted to subpol ar regions of the North Pacific. The glacial-interglacial average SST change determined in this study is considerably larger than the 2 degr ees C change estimated by Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) [1981]. We propose that a strengthened Califor nia Current flow was associated with the advance of subpolar surface w aters into the Borderlands region during the last glacial.