WATER SHEET OUTBURST FLOODS FROM THE LAURENTIDE ICE-SHEET

Field evidence and a theoretical model support the concept that during Wisconsinan glaciation subglacial water sheet outburst floods issued from a large subglacial lake located in the Hudson Bay basin. The lake was fed by supraglacier meltwater that was trapped in a depressed ice lid over the lake. Water may have also fed the lake by reversed outburst floods from proglacial lakes, particularly after 9000 BP, when a very low ice elevation over Hudson Bay is calculated. Deglaciation was accelerated by surges associated with the lift-off of ice by the sheet floods; ice lobe extensions the order of 100 km are possible. The model supports the concept of a multidomed Laurentide Ice Sheet in the form of an annular dome around Hudson Bay.