Corrigendum to “The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin” [Earth-Science Reviews volume 208 (2020) 103181]

Formation of murtoos by repeated flooding of ribbed bedforms along subglacial meltwater corridors

“…The reconstruction of subglacial hydrological systems and routes is critical for inferring basal thermal regimes (Kleman and Hattestrand, 1999;Irvine-Fynn et al, 2011;Smith-Johnsen et al, 2020), meltwater discharge fluctuations (Moon et al, 2014;Simkins et al, 2017;O'Connor et al, 2020), flow dynamics (Iken and Bindschadler, 1986;Anandakrishnan and Alley, 1997;Bell et al, 2007;Schroeder et al, 2013;Williams et al, 2020) and frontal ablation (Slater et al, 2015;Fried et al, 2019) of ice masses. Palaeoglaciology can help reconstruct past subglacial hydrological systems from the geomorphological imprints left behind by palaeo-ice sheets to understand their evolution and dynamics during deglaciation (St-Onge, 1984;Cofaigh, 1996;Rampton et al, 2000;Utting et al, 2009;Storrar and Livingstone, 2017;Lewington et al, 2019;Ojala et al, 2019;Coughlan et al, 2020) and extrapolate these findings to contemporary ice sheets. New high-resolution (<5 m) Digital Elevation Models (DEMs) based on aerial LiDAR data enable the glacial geomorphological records to be more accurately deciphered through revised mapping, identification of previously unrecognized landforms and more accurate morphometric analyses.…”

“…Recent studies conducted in Scandinavia unraveled hitherto unidentified subglacial bedforms characterized by a triangular shape. These bedforms, referred to as murtoos (Ojala et al, 2019;Peterson Becher and Johnson, 2021) or triangle-type murtoos (Ojala et al, 2021), were initially called 'V-shaped hummocks' (Peterson et al, 2017) and 'triangular-shaped landforms' (Mäkinen et al, 2017). In plan view, murtoos are triangles with a longitudinal axis of symmetry parallel to the ice flow direction and a tip pointing downstream.…”

“…In plan view, murtoos are triangles with a longitudinal axis of symmetry parallel to the ice flow direction and a tip pointing downstream. Murtoos are 30 to 200 m long and wide, less than 5 m high and have asymmetric longitudinal profiles with sharp and steep downstream edges (Ojala et al, 2019).…”

“…Hummock tracts are a few kilometers wide and several to tens of kilometers long and are interpreted as routes that drained pulses of meltwater flow beneath decaying ice sheets (Peterson and Johnson, 2018). These routes were first observed as 'glaciofluvial corridors' in Canada (St-Onge, 1984;Utting et al, 2009), and were more recently referred to as 'meltwater corridors' (Lewington et al, 2019(Lewington et al, , 2020Ojala et al, 2019;Sharpe et al, 2021), a term that we use in the article.…”

“…Murtoos have been interpreted to form by a combination of erosion, deposition and deformation of water-saturated sediments and subglacial till when large volumes of meltwater are delivered to warm subglacial beds (Mäkinen et al, 2017;Ojala et al, 2019;Peterson Becher and Johnson, 2021;Ahokangas et al, 2021). These periodic meltwater inputs are likely to cause flooding events overwhelming channelized or hydraulically connected distributed drainage systems along meltwater corridors (e.g., Lewington et al, 2020;Mejía et al, 2021;Nanni et al, 2021).…”