During the past several years, ODP has been drilling in the Atlantic Ocean to study past changes in Earth's climate. Leg 177 represents the southernmost anchor of sites needed to complete the Atlantic paleoceanographic transect. The strategy during Leg 177 was to drill a series of sites along a north-south transect that encompasses the past dynamic range of the Antarctic sea-ice field and frontal boundary movements within the ACC. Sites were also selected along a bathymetric gradient, ranging from 1974 to 4620 m, to study changes in deep-water circulation.
The drilling strategy included seven primary sites to recover expanded late Neogene sections across latitude and depth in the Subantarctic and Antarctic regions. We specifically targeted sites with high sedimentation rates on drift deposits and in the region of the circum-Antarctic opal belt (Fig. F9 ).Four of the sites (1089, 1091, 1093, and 1094) exhibit average sedimentation rates exceeding 100 m/m.y., offering the opportunity for paleoclimatic studies at millennial scale resolution or higher. The two southern sites (1093 and 1094) are the first to recover a complete composite section by triple-APC/XCB coring from the circum--Antarctic opal belt.