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The AAPG/Datapages Combined Publications Database
A study of deep-sea cores, which approximate the extent of the California Current, indicates that faunal changes occur at or near the lithologic Pleistocene-Holocene boundary off San Francisco and Los Angeles, California, but generally below this boundary off Cedros Island, Baja California. In upper Pleistocene rocks there are (1) a marked increase of radiolarian tests per gram of dry sediment; (2) a sharp decrease in both planktonic foraminiferal tests per gram of dry sediment and in the median size of Turborotalia pachyderma, except off Los Angeles, where the trend is reversed; (3) an increase in the percentage of dextral-coiling Turborotalia pachyderma; (4) an influx of several rare planktonic foraminiferal species; and (5) a decrease in the relative abundance of Globi erina bulloides off San Francisco, of Turborotalia pachyderma off Los Angeles, and of Globigerina quinqueloba off Cedros Island, with a corresponding increase in relative abundance of Globigerina quinqueloba off San Francisco and Los Angeles and an increase of both Neogloboquadrina dutertrei and Turborotalia pachyderma off Cedros Island.
A period of seasonal warming in the early Wisconsin is indicated in the temperate Pacific Ocean. This assumption is based on the abundance of large temperate planktonic foraminiferal species per gram of dry sediment in the cores from off Los Angeles. This warming period correlates with the "warm interval" reported elsewhere.
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