A 2000 YR RECORD OF SACRAMENTO-SAN-JOAQUIN-RIVER INFLOW TO SAN-FRANCISCO BAY ESTUARY, CALIFORNIA

Oxygen and carbon isotopic measurements of fossil bivalves (Macoma nas uta) contained in estuarine sediment are used to reconstruct a late Ho locene record of salinity and stream flow in San Francisco Bay. Discha rge into the bay is a particularly good indicator of paleoclimate in C alifornia because the bay's influent streams drain 40% of the state, T he isotopic record suggests that between about 1670 and 1900 calendar years (yr cal) B.P. inflow to the bay was substantially greater than t he estimated prediversion inflow of 1100 m(3)/s, An unconformity repre senting a 900 yr hiatus is present in the core between 1670 and 750 yr cal B.P., possibly caused by a major hydrological event. Over the pas t 750 yr, stream flow to San Francisco Bay has varied with a period of 200 yr; alternate wet and dry (drought) intervals typically have last ed 40 to 160 yr.