The extreme yet transient nature of glacial erosion

Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet — the third largest Quaternary ice mass that spanned 49°N to 82°N — to decipher its erosional footprint during the entire last ~100 ka glacial cycle. Our results demonstrate extreme spatial and temporal heterogeneity in subglacial erosion, with rates ranging from 0 to 5 mm a−1 and a net volume equating to ~130,000 km3 of bedrock excavated to depths of ~190 m. A hierarchy of environmental controls ostensibly underpins this complex signature: lithology, topography and climate, though it is basal thermodynamics that ultimately regulates erosion, which can be variously protective, pervasive, or, highly selective. Our analysis highlights the remarkable yet fickle nature of glacial erosion — critically modulated by transient ice-sheet dynamics — with its capacity to impart a profound but piecemeal geological legacy across mid- and high latitudes

A time-transgressive perspective of glacial erosion and meltwater beneath the Eurasian ice sheet

Academic presentation at The 4th International PalaeoArc Conference, Akureyri, Iceland, 27.08.23 - 30.08.23. https://www.arcus.org/events/arctic-calendar/34282.The efficacy and controls governing glacial erosion over geological timescales are intricately linked yet remain poorly understood and contended. By assimilating geophysical data with modelling of the Eurasian Ice Sheet - the third largest Quaternary ice mass that spanned 49°N - 82°N - we decipher its erosional footprint during the last ~110 ka glacial cycle. Our results demonstrate extreme spatiotemporal heterogeneity in erosion with short-term rates ranging from 0 - 5 mm a-1 , and a net volume equating to ~130,000 km3 of bedrock excavated to depths of ~190 m. A hierarchy of environmental controls ostensibly underpins this signature: lithology, topography and climate, though it is basal thermodynamics that ultimately regulates erosion, which can be variously protective, pervasive, or, highly selective. A notable signature of this thermomechanically regulated erosional footprint is an increase in the intensity of erosion across upland areas of Fennoscandia and within troughs in the Barents Sea during the last deglaciation compared to the long-term mean. New meltwater landforms mapped from multibeam bathymetry data collected in the Central Barents Sea capture insight into the evolving nature of the subglacial environment of the Barents Sea ice sheet as it thinned and collapsed; the apparent abundance of basal meltwater, which we interpret was increasingly being supplemented by inputs from supraglacial melting, likely contributed to elevated erosion of the sedimentary substrate and the mobilisation of subglacial sediments during the latter stages of deglaciatio