Low-gradient outlet glaciers lice streams?) drained the Laurentide ice sheet

摘要

Observations of geomorphic features dated with cosmogenic nuclides are used to determine the configuration of glaciation in Cumberland Sound, Baffin Island, during the last glacial maximum. Cumberland Sound, which was a major drainage of the Laurentide Ice Sheet at its northeastern (Arctic Canada) margin, contained low-gradient ice with a surface slope of similar to0.03 degrees and a driving stress between 2 and 7 kPa. These values are similar to those observed for the ice streams that dominate the dynamics of the West Antarctic ice sheet today. The presence of low-gradient ice in Cumberland Sound and other major outlets may similarly have influenced Laurentide ice sheet behavior and would account for the iceberg discharge episodes that produced the Heinrich-event debris layers observed in North Atlantic ocean sediments. [References: 24]