Site 1225 is located in the eastern equatorial Pacific near the boundary between the South Equatorial Current and the North Equatorial Countercurrent west of the East Pacific Rise (Fig. F1). The site lies in the topographic high created by the rain of biogenic debris from the relatively high productivity equatorial ocean. Site 1225 is adjacent to Ocean Drilling Program (ODP) Leg 138 Site 851. The main features of the sedimentary succession were documented during Leg 138 (Shipboard Scientific Party, 1992; Pisias, Mayer, Janacek, Palmer-Julson, and van Andel, 1995). However, magnetostratigraphy at Site 1225 was not measured or interpreted below 150 meters below seafloor (mbsf) based on the assumption that diagenesis had destroyed the magnetic signal (Shipboard Scientific Party, 1992). More efficient shipboard measurements at Site 1225 illustrated a second zone containing magnetic polarity below 200 mbsf (Shipboard Scientific Party, 2003). The goal of this project is to refine the chronology of this site using both magnetostratigraphic and biostratigraphic techniques.