Glacial geomorphology between Lake Vänern and Lake Vättern, southern Sweden

Abstract

The glacial geomorphology between the lakes Vänern and Vättern is presented on a 1:220,000 scale, LiDAR-based map covering approximately 18,000 km 2. Fifteen landform units have been mapped; end moraines, De Geer moraines, drumlins, crag-and-tails, hummock tracts and corridors, irregular ridges, murtoos, eskers, deltas/sandur, outwash complexes, meltwater channels, boulder bars/sheets, the Timmersdala ridge, raised shorelines, sand dunes and prominent landslide scars (the last three are post-glacial). The area includes moraines associated with the Younger Dryas cold interval and drainage deposits of the Baltic Ice Lake. Additionally, the map reveals previously undetected geomorphic features including (1) murtoos, (2) abundant traces of meltwater erosion manifested as channels and hummock corridors, (3) laterally extensive end-moraine systems (the Remmene and Kungslena icemargin positions) and (4) the distinct lobate shape of end moraines formed above the highest shoreline. This map provides a uniform base for future use in georesources, paleo ice-sheet modelling, geologic history, and geoconservation.

Geomorphology and sedimentology of features formed at the outlet during the final drainage of the Baltic Ice Lake

“…1; Öhrling et al . 2020) support the interpretation of a 150‐m level for the BIL immediately prior to drainage.…”

“…Ice‐marginal drainages are a distinct feature in the region (Öhrling et al . 2020), and they mark the subaerial drainage of temporary ice‐dammed lakes. These channels elsewhere have been protected from subsequent erosion because spillway erosion is followed by subsequent ice retreat and lake‐level fall, indicating if they had been formed at Billingen, they would be visible.…”

“…Map has been produced for this paper but is also modified from Johansson & Dreyer Isaksson (2013); Dreyer Isaksson & Johansson (2013) and Öhrling et al . (2020). H = Hornsberg; BD = location of cores taken by Björck & Digerfeldt (1984); JL = approximate location of clay pit investigated by Johansson (1926) and Lundqvist et al .…”

Late erosion pulse triggered by rapid melt in the cold‐based interior of the last Fennoscandian Ice Sheet, an example from Rogen

“…The anastomosing pattern and sharp boundaries of widespread hummock tracts and their close association with murtoos suggest large pulses of subglacial meltwater drainage through meltwater corridors (Öhrling et al, 2020; Peterson et al, 2017; Peterson Becher & Johnson, 2018; Rampton, 2000). We interpret the murtoos as a deposition of till (Peterson Becher & Johnson, 2021), reworked from ribbed moraines (Vérité et al, 2022), whereas the isolated mounds are interpreted as partly disintegrated ribbed moraines retaining boulder‐covers and an unmoved core.…”

“…Meltwater landforms were subdivided into: (i) hummock tracts and corridors; (ii) meltwater channels; and (iii) lateral channels. Hummock tracts are mapped according to the disorganized character with irregular mounds, ridges and depressions (Öhrling et al, 2020; Peterson et al, 2017). Sharp boundaries between hummock tracts and smooth till plain are mapped as hummock corridors (Öhrling et al, 2020; Peterson Becher & Johnson, 2018).…”