FIGURE 7 Top left: ANDRILL drill rig in the McMurdo Sound. Top right: Conducting core analysis on site. Bottom: Core in core trays.

SOURCE: Images are from www.andrill.org.

graphic records retrieved from these boreholes will cover critical time periods in the development of Antarctica’s major ice sheets. The sediment cores will be used to construct an overall glacial and interglacial history for the region, including documentation of sea-ice coverage, sea level, terrestrial vegetation, and meltwater discharge events. The cores will also provide a general chronostratigraphic framework for regional seismic studies to help unravel the area’s complex tectonic history. The first borehole was drilled in 2006-2007, and drilling the second borehole will begin in the 2007-2008 field season.

“Plates and Gates” is a multidisciplinary project aimed at understanding key polar oceanographic gateways for major water masses. Ocean gateways are the deepwater passageways that form as continents rift apart and that are destroyed when ocean basins close (Figure 8). As part of the global ocean circulation, water masses move through these passageways, and major shifts in the ocean gateways produce changes in the transport of heat, salt, and nutrients. These changes in global ocean circulation may trigger changes in global climate. Plates and Gates will establish detailed tectonic, geodynamic, sedimentary, and paleotopographic histories of major oceanic gateways, providing basic constraints for global climate modeling. In Antarctica, key areas are the Drake Passage and the former Tasman Gateway, the last barriers to the establishment of the Antarctic Circumpolar Current. The Antarctic Circumpolar Current is the fundamental vehicle for mass flux between the Pacific, Atlantic, and Indian oceans and has the largest flux of all the globe’s ocean