The timing of retreat along sectors within the EAIS appears diachronous, and in places occurred prior to the LGM.
It’s noteworthy that so few identified both the named groupings and their (then-)current geographical distributions with such accuracy in an arena then so new to the gaze of social and cultural scientists.
Here I assume that most readers of these pages are scientifically-informed in a general sense but not experts in historical linguistics.
My own formal linguistic training (historical and otherwise) was largely limited to a few courses given by Stanley Newman (a master linguist of his time, to be sure) in the Department of Anthropology at the University of New Mexico in the 1950s, but from that brief contact I did develop lasting respect for and interest in the science of linguistic reconstruction.
An emerging body of evidence from studies of the last glacial/interglacial cycle suggests that the East and West Antarctic ice sheets have not advanced and retreated in concert.
The West Antarctic ice sheet advanced to the outer shelf in most regions during the Last Glacial Maximum (LGM).
The retreat from the shelf commenced shortly after the LGM and continued into the late Holocene.
The West Antarctic Ice Sheet in Ross and Amundsen seas slid across a deforming bed, at least during the final phases of extended glaciation.
This implies that at this time the ice sheet had a low profile.
Differences in the number and locations of grounding-zone wedges and smaller grounding zone features from trough to trough imply that individual West Antarctic Ice Sheet ice streams retreated episodically.
Details concerning the expansion, retreat, and behavior of the East Antarctic Ice Sheet (EAIS) are more sparse.
The picture emerging is that the EAIS did not expand to the continental shelf edge during the LGM; rather, it achieved a maximum extent of a mid-shelf position in some locations, while in other areas the ice terminus was situated near its present location.