Late Cenozoic deposits at Reedy Glacier, Transantarctic Mountains: implications for former thickness of the West Antarctic Ice Sheet

Deposits corresponding to multiple periods of glaciation are preserved in ice-free areas adjacent to Reedy Glacier, southern Transantarctic Mountains. Glacial geologic mapping, supported by ¹⁰Be surface-exposure dating, shows that Reedy Glacier was significantly thicker than today multiple times during the mid-to-late Cenozoic. Longitudinal-surface profiles reconstructed from the upper limits of deposits indicate greater thickening at the glacier mouth than at the head during these episodes, indicating that Reedy Glacier responded primarily to changes in the thickness of the West Antarctic Ice Sheet. Surface-exposure ages suggest this relationship has been in place since at least 5 Ma. The last period of thickening of Reedy Glacier occurred during Marine Isotope Stage 2, at which time the glacier surface near its confluence with the West Antarctic Ice Sheet was at least 500 m higher than today.