Formalising an inversion methodology for reconstructing ice‐sheet retreat patterns from meltwater channels: application to the British Ice Sheet

Abstract

2007. Formalising an inversion methodology for reconstructing ice-sheet retreat patterns from meltwater channels: application to the British Ice Sheet.ABSTRACT: Glacial meltwater channels yield important information regarding patterns of palaeo-ice-sheet retreat. However, it is important to distinguish between channels formed at different positions in relation to the ice mass (e.g. lateral, subglacial). In Britain, whilst meltwater channels have been widely reported in the literature, such categorisation is often lacking. Here we develop an inversion methodology for extracting ice margin retreat patterns from meltwater channels. Diagnostic geomorphological criteria are presented, derived from published descriptions of meltwater channel form, by which a channel of unknown origin may be assigned to its appropriate category. These criteria are applied to channels recorded in the BRITICE GIS database of glacial landforms and we find most channels to be of lateral or subglacial origin. The categorisation of channels enables palaeomargin positions and the direction of retreat-stage ice flow to be approximated, and a preliminary reconstruction is made of fragments of the ice-sheet retreat pattern. Further mapping and integration of melt traces with other geomorphic data will permit a more complete palaeo-glaciological reconstruction of the last British Ice Sheet.

Reconstructing the confluence zone between Laurentide and Cordilleran ice sheets along the Rocky Mountain Foothills, south‐west Alberta

“…Meltwater channels have also been genetically classified (ice-marginal or proglacial) using standard criteria (e.g. Greenwood et al, 2007; Table 1). These data were used to reconstruct the temporal evolution of ice-flow patterns across the region based on the flowset approach.…”

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

“…Ice sheet reconstructions have used ice-marginal meltwater channels, spillways, glacial lake shorelines and deltas, to trace former ice margins and reconstruct ice retreat patterns (Kleman, 1992;Jansson, 2003;Kleman et al, 2006;Greenwood et al, 2007;Margold et al, 2013a, b). These landforms are particularly important in areas of formerly cold-based ice that prevented the formation of glacial lineations or eskers (Kleman, 1992).…”

Glacial geomorphology of the northern Kivalliq region, Nunavut, Canada, with an emphasis on meltwater drainage systems

“…Many modern channels therefore occupy former meltwater channels, making them difficult to objectively separate. All potential meltwater channels were therefore mapped and individually assessed to determine whether they formed subglacially, ice-marginally or proglacially (after Greenwood, Clark, & Hughes, 2007). The criteria for distinguishing subglacial meltwater channels include: (i) an association with other glacial landforms such as moraines and eskers; (ii) an undulating channel thalweg and (iii) an oblique channel orientation relative to the regional drainage slope.…”

“…Ice-marginal meltwater channels document the ice margin at the time of their formation and are classically related to parallel flights of lateral channels perched on valley sides (e.g. Dyke, 1993;Greenwood et al, 2007;Maag, 1969;Margold, Jansson, Kleman, & Stroeven, 2011).…”