This is a study of chemical changes in foraminifera shells from the Miocene epoch and rom the Tertiary/Cretaceous boundary layer. Specifically, the investigator will determine the cadmium to calcium ratio in Miocene benthic foraminifera from the Indian, North Atlantic, and Antarctic Circumpolar Oceans; the Cd/Ca ratio in benthic foraminifera from marine sections across the K/T boundary; and the feasibility of modifying methodology to measure Cd/Ca ratios in planktonic foraminifera and fine fraction calcium carbonate. The results will yield insights into paleoceanic circulation patterns and into paleoceanic trace metal and nutrient inventories during the Miocene and across the K/T boundary.