Marguerite bay laceration

Marguerite Bay or Margaret Bay is an extensive bay on the west side of the Antarctic Peninsula, which is bounded on the north by Adelaide Island and on the south by Wordie Ice Shelf, George VI Sound and Alexander Island. A new paper reports glacial geological data that provide evidence for the timing of ice-sheet retreat and thinning at the end of the last glaciation (~10,000 years ago) in Marguerite Bay. The length of time that rock outcrops have been exposed was dated which allow dating of the thinning of the ice sheet, and the record from seabed sediments. This then allows the determination of how the ice sheet retreated across the continental shelf. The dating shows a surprising pattern. About 9,600 years ago, the ice in Marguerite Bay appears to have thinned very quickly indeed, an observation that turns out to be consistent with several other datasets from the same area (ice-shelf collapse histories, raised beaches and lake sediment cores). Further north, around Vernadsky Station, the ice-sheet retreat was much more gradual. Thus the rapid retreat of ice in Marguerite Bay was rather localized, and probably driven by specific local conditions. Indeed, there is some evidence that the retreat occurred at a time when warmer water was present on the continental shelf, leading us to suggest that the Marguerite Bay ice stream may have been destabilized, at least in part, by changes in the ocean. This finding supports recent observations that suggest a strong oceanic influence on ice-sheet change, and has implications for future stability of other parts of the Antarctic ice sheet. In other words a change in the direction of an ocean current may have a strong impact on ice sheet formation and development.