| Summary: | Abstract: We present evidence for the absence of the George VI Ice Shelf during a brief period in the mid-Holocene and during one or more earlier interstadials or interglacials. Barnacle Bathylasma corollcorme shells sampled from ice shelf moraines at Two Step Cliffs on Alexander Island have been dated to c. 5750-6000 I4C yr RP(C. 6550-6850 cal yr BP) and imply seasonally open water in the George VI Sound during this period. Other shells are beyond the range of radiocarbon dating and imply open water during one or more previous interglacial or iiiterstadial period, prior to 40 000 I4C yr BP. Our results show that the ongoing collapse of some Antarctic Peninsula ice shelves is not unprecedented.
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