On the formation of large subglacial lakes

Abstract

The role of subglacial water storage beneath continental ice sheets is investigated, primarily for a deformable bed. Subglacial ponding is shown to occur under most regions of warm-based ice sheets, and large subglacial lakes can become established, for example in the Hudson Bay basin. The formation of large lakes depends upon the fact that the ice-surface gradient is reduced once subglacial ponding occurs and upon the feedback between the reduced ice-surface gradient and increased subglacial ponding. Subglacial ponding likely played a large role in determining the ice-sheet topography during late deglaciation and in speeding up the deglaciation process.

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

“…Nonetheless, there is strong theoretical support for their existence (e.g. Shoemaker, 1991;Livingstone et al, 2012bLivingstone et al, , 2013 and palaeo-ice surface and bed topographies can be used to calculate 3-D hydraulic potential surface (Shreve, 1972). Evatt et al (2006) were the first to consider this method at the ice-sheet scale and predicted where subglacial lakes might have formed under the LIS at the LGM.…”

“…There is also an extensive literature and long history on proposed subglacial (mega-) flood tracts (e.g. Shaw, 2002), which have been linked to large palaeo-subglacial lake outburst events (Shoemaker, 1991(Shoemaker, , 1999. However, in some cases, the use of subglacial bedforms (e.g.…”

Fresh arguments against the Shaw megaflood hypothesis. A reply to comments by David Sharpe on “Paleohydraulics of the last outburst flood from glacial Lake Agassiz and the 8200 BP cold event”

“…Shoemaker (1991Shoemaker ( , pp. 1978Shoemaker ( -1979 proposed that as an ice sheet advanced over pre-existing water bodies (e.g.…”

Subglacial water-sheet floods, drumlins and ice-sheet lobes

“…Of relevance is the recent evidence that one of the Antarctic subglacial lakes (Vostok) is much larger than previously thought, about the size of Lake Ontario (Kapitsa and others, 1996).During a period of rapid deglaciation, a large supraglacial lake can create temperate ice beneath it. The possibility exists of catastrophic drainage from such a lake through temperate icc to a subglacial lake (Shoemaker, 1991). This implies that subglacial lakes beneath a deglaciating Laurentide ice sheet could have collected water much more rapidly than contemporary Antarctic subglacial lakes.…”