MELTWATER LANDFORM PERSPECTIVES ON SUBGLACIAL HYDROLOGICAL PROCESSES: INSIGHTS FROM HIGH-RESOLUTION MAPPING IN NORTHERN CANADA
This presentation summarises recent holistic mapping efforts, which reveal diverse meltwater traces forming an integrated network across northern Canada. Eskers are typically surrounded and joined by wider meltwater corridors (100s to 1000s m wide) that comprise both erosional and depositional forms (such as hummocks, ridges, murtoos), including subglacial bedforms (e.g. ribbed moraine tracts). We suggest that meltwater corridors formed by the exchange of water and sediment between a conduit (esker) or efficient core and the surrounding hydraulically-connected distributed drainage system (corridor) in response to variable melt inputs. The landform signature of meltwater corridors is likely influenced by different styles of drainage (e.g. from laterally constrained floods to distributed drainage) and coupling with the ice above. Eskers are interpreted to record a composite signature of ice marginal drainage. This interpretation is based on the close 1:1 association between beaded eskers (series of aligned sediment mounds) and De Geer moraine (i.e., each bead is associated with a corresponding ridge) in Keewatin, which suggests that they are quasi-annual ice-marginal deposits formed time-transgressively at the mouth of subglacial conduits during deglaciation.