![]() Grounding-line retreat is estimated to have averaged between ~ 100 ± 32 and ~ 700 ± 79 ma −1. Both scenarios require sustained rapid retreat that exceeded several centuries. ![]() The end-members fluxes correspond to deposition rates for buttressed and unbuttressed ice stream flow. We used two end-member paleo-sediment fluxes, i.e., accumulation rates, to convert the cumulative sediment volumes of the ridge field to elapsed time for measured distances of grounding-line retreat. Here, we reconstruct the pattern, duration and rate of retreat from a backstepping succession of small-scale grounding-zone ridges that formed on the embayment’s eastern flank. By ~ 11.5 ± 0.3 cal kyr BP, dynamic thinning of grounded ice triggered a retreat that opened a ~ 200-km grounding-line embayment on the Whales Deep Basin (WDB) middle continental shelf. The accelerated mass loss led to a significant negative mass balance that re-organized WAIS flow across the central and eastern Ross Sea. ![]() There, an ice shelf breakup at 12.3 ± 0.6 cal. (calibrated) kyr BP caused accelerated ice-mass loss from the Bindschadler Ice Stream (BIS). An abrupt retreat of the West Antarctic Ice Sheet (WAIS) that occurred during the early deglaciation is well recorded on the eastern Ross Sea continental shelf. Geological records of ice sheet collapse can provide perspective on the ongoing retreat of grounded and floating ice.
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