Ice-marginal terrestrial landsystems: Sediment heterogeneity, architecture and hydrogeological implications

Previously glaciated landscapes often present unique challenges for hydrogeological investigations. Specifically, ice-marginal terrestrial landsystems are often difficult to characterize and model considering the dynamic nature of the ice and associated meltwater and sediment gravity flow processes that result in heterogeneous sediment successions and architectures over a range of scales. This paper integrates the many advances in our understanding of glacial geology with a focus on its hydrogeological implications. Ice-marginal terrestrial landsystems can be conceptualized as complex arrangements of glacial conditions that vary as the ice margin stagnates or fluctuates over time. Subglacial, englacial, proglacial, glaciofluvial, glaciolacustrine and gravitational or glacitectonic deformation processes lead to erosional and depositional elements that stack over time to form complex subsurface successions with uncertain lateral variability. The geomorphology and sediments at surface within an area are the last expression of those erosional and depositional elements over time. The nature and architecture of sediment types expected in eight different settings are reviewed and their hydrogeological significance discussed. The evolution of a contaminated site's conceptual model is then used to demonstrate how detailed sedimentological and stratigraphic characterization of glacial successions together with an understanding of ice-marginal landsystems, can lead to a more robust site conceptual model of hydraulic conductivity architecture that can better constrain hydrogeological investigations.