How do grounding line fluctuations affect upstream ice? This is a fundamental question which we have attempted to illuminate using observations of geomorphology on the seafloor of the western Ross Sea. Subglacial and ice-marginal landforms tell us that East Antarctic ice flowed through the Transantarctic Mountains into the Ross Embayment during the Last Glacial Maximum (LGM) to occupy Drygalski, JOIDES, and Pennell troughs. Following the LGM, retreating ice unzipped through JOIDES and Pennell troughs to form a large embayment in the grounding line. This triggered drawdown and enhanced flux through the southern Drygalski outlet glaciers that drove a major reorganization of flow in Drygalski Trough from northward- to southward-flowing and caused ice to readvance about 50 kilometers through southern JOIDES Trough, delivering a significant volume of ice back to the ocean. Click on the image of the manuscript header to read more!

The images below show the configuration of the ice sheet embayment in JOIDES and Pennell Troughs, followed by the configuration of ice after the readvance of outlet glaciers through southern Drygalski Trough into southern JOIDES Trough.