We present radio-echo sounding data and satellite imagery, revealing a series of ancient large sub-parallel subglacial channels preserved in the region between the Möller and Foundation Ice Streams, West Antarctica. We suggest these newly-recognised channels were formed by significant water routed along the ice-sheet bed. Taking into account the present geographical and hydrological setting of the channels, we find a subglacial lake source for channel formation less likely than water originating from the ice surface. The Greenland Ice Sheet today exemplifies how significant seasonal surface melt is transferred to the bed via englacial routing. For West Antarctica, the Pliocene (2.6-5.3 Ma) represents the most recent sustained period when temperatures could have been high enough to generate surface melt comparable to Greenland today. We propose, therefore, that a temperate ice sheet was present (at least periodically) in this location under ancient warm conditions during, and prior to, the Pliocene.
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