Hokkaido University, Japan

As the world's largest ocean, the Pacific is intricately linked to major changes in the global climate system. Throughout the Cenozoic, Pacific plate motion has had a northward component. Thus, the Pacific is unique in that the thick sediment bulge of biogenic-rich deposits from the currently narrowly focused zone of equatorial upwelling is slowly moving away from the Equator. Hence, older sections are not deeply buried and can be recovered by drilling. Previous drilling in this area during Ocean Drilling Program (ODP) Legs 138 and 199 was remarkably successful in giving us new insights into the workings of the climate and carbon system, productivity changes across the zone of divergence, time-dependent calcium carbonate dissolution, bio and magnetostratigraphy, the location of the Intertropical Convergence Zone (ITCZ), and evolutionary patterns for times of climatic change and upheaval. Together with older Deep Sea Drilling Project drilling in the eastern equatorial Pacific, both legs also helped to delineate the position of the paleoequator and variations in sediment thickness from approximately 150 degrees W to 110 degrees W.