Subglacial meltwater routes of the Fennoscandian Ice Sheet

Abstract

Subglacial drainage systems are crucial elements of glaciers and ice sheets because they modulate ice flow velocity. However, logistical challenges of measuring subglacial processes beneath contemporary ice and natural limitations in long-term monitoring hinder our understanding about their spatio-temporal evolution. Subglacial meltwater landforms created by palaeo-ice sheets are records of past subglacial drainage systems and offer the potential to study their large-scale development throughout deglaciation. Although collectively recording subglacial drainage, individual meltwater landforms such as eskers, meltwater channels and meltwater corridors, which comprise tunnel valleys and meltwater tracks (assemblages of landforms in broad, elongated paths with irregular surface texture), have mostly been investigated as separate entities. Using high-resolution (1–2 m) digital elevation models, we map integrated networks of subglacial meltwater landforms, herein called subglacial meltwater routes, on an ice-sheet scale in Fennoscandia. Our map provides a basis for future research on the long-term evolution of subglacial drainage networks and its effect on ice dynamics of the Fennoscandian Ice Sheet.

Conceptual model for the formation of bedforms along subglacial meltwater corridors (SMCs) by variable ice‐water‐bed interactions

“…Hummocks are commonly gathered along corridors – 10s to 100 km in length and 1 to 5 km in width – roughly parallel to former ice flow directions. Hummock corridors radiate out from palaeo‐ice domes in the FIS and LIS and are mostly perpendicular to morainic complexes demarcating ice lobe positions during deglaciation phases (Dewald et al, 2022; Lewington et al, 2020; Peterson et al, 2017).…”

“…In the following section, we describe the morphological and patterning characteristics of a range of bedform assemblages, each associated with a predominant bedform type and defined as a bedform tract, which contributes to the reconstruction of SMCs (Dewald et al, 2022; Lewington et al, 2020). Although it is convenient to distinguish the different bedform tracts observed along the SMCs based on predominant bedform types, lateral and longitudinal transitions exist between these tracts and surrounding bedforms, sometimes making clear boundaries difficult to define.…”

“…Lewington et al, 2020; Peterson et al, 2017; Peterson & Johnson, 2018). Mapping of meltwater traces from high‐resolution (1–2 m) digital elevation models has revealed SMCs to be widespread beneath the former Laurentide (LIS) and Fennoscandian (FIS) ice sheets (Figure 1) (Ahokangas et al, 2021; Dewald et al, 2022; Lewington et al, 2020; McMartin et al, 2021; Öhrling et al, 2020; Peterson et al, 2017). The large‐scale distribution of SMCs largely mirrors and extends that of eskers forming networks roughly parallel to ice flow that radiate out from former ice divides (Figure 1).…”

“…Mapped subglacial meltwater traces (blue lines) and locations of Figures 2‐12 in (a) Keewatin, Canada (Lewington et al, 2020) and (b) Fennoscandia (Dewald et al, 2022). See detailed locations of Figures 2‐12 in Table S1.…”

Variations in hydraulic efficiency of the subglacial drainage landsystem control surging and streaming regimes of outlet glaciers

“…The efficiency of subglacial drainage is known to control subglacial bed deformation, erosion and glacier dynamics (Benediktsson and others, 2009; Phillips and others, 2013; Lewington and others, 2020) and thus also the shaping of subglacial landscapes and their constitutive subglacial landform and bedform assemblages (Mäkinen and others, 2017; Vérité and others, 2021, 2022; Dewald and others, 2022). In the light of our experimental and mapping results, we intend to establish a relation between the morphological expression of drainage efficiency and ice flow dynamics to refine landsystem models of either surging or streaming ice lobes (Fig.…”