Megaflutes in the Menteith Hills, Central Scotland

Abstract

‘Flutings’ or ‘flutes’ are elongated, flow-parallel subglacial bedforms associated with relatively fast flowing glaciers. Analysis of recently acquired high-resolution (50 cm) LiDAR data has identified the presence of large, very low-relief flutings on the Menteith Hills in Central Scotland. These subtle landforms, up to 1 km in length and 10s of metres wide, are interpreted as ‘megaflutes’, falling in between the accepted definition of flutes and the much longer mega-scale glacial lineations. This new geomorphological evidence mapping suggests that the palaeo Teith Glacier grew thick enough to breach the local watershed, forcing a branch of glacier ice to flow into the Forth Valley. The megaflutes are located near the accepted Loch Lomond Stadial (Younger Dryas Stadial) limits in the area, yet are currently undated. Flutes are difficult to identify in the field, on aerial imagery or digital elevation models with ≤ 5 m resolution due to their low-relief and/or often widespread vegetation cover. LiDAR is therefore a valuable tool for revealing these landforms where they would otherwise go unnoticed. This new research offers a fresh perspective for the glacier landform record in a key part of Central Scotland and highlights the importance of high-resolution LiDAR data for mapping subtle glacial geomorphology.