High-resolution digital elevation models of Finland and Sweden based on LiDAR (Light Detection and Ranging) reveal subglacial landforms in great detail. We describe the ice-sheet scale distribution and morphometric characteristics of a glacial landform that is distinctive in morphology and occurs commonly in the central parts of the former Scandinavian Ice Sheet, especially up-ice of the Younger Dryas end moraine zone. We refer to these triangular or V-shaped landforms as murtoos (singular, ‘murtoo’). Murtoos are typically 30–200 m in length and 30–200 m in width with a relief of commonly <5 m. Murtoos have straight and steep edges, a triangular tip oriented parallel to ice-flow direction, and an asymmetric longitudinal profile with a shorter, but steeper down-ice slope. The spatial distribution of murtoos and their geomorphic relation to other landforms indicate that they formed subglacially during times of climate warming and rapid retreat of the Scandinavian Ice Sheet when large amounts of meltwater were delivered to the bed. Murtoos are formed under warm-based ice and may be associated with a non-channelized subglacial hydraulic system that evacuated large discharges of subglacial water.

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.

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