Morphology and stratigraphy from several deglaciations in the Transtrand Mountains, western Sweden

The Transtrand Mountains, western Sweden, are characterised by an abundance of glaciofluvial meltwater channels. Crossing lateral channels and channel systems overprinted by fluting occur at several localities. Drainage channel systems from three older deglaciations are interpreted to have been preserved despite overriding by later ice sheets. Deep sections, machine excavated into the summit surface of the Hundfjället Mountain, revealed the presence of two lower diamictons into which two older generations of lateral channels were cut, and subsequently buried by a Late Weichselian basal till. Buried frost‐sorted structures, and frost‐fractured bedrock below the lowermost till, indicate the repeated occurrence of periglacial condil conditions. An organic layer between the two older units yielded an infinite radiocarbon age of > 45000 yr BP. The pollen content of this layer indicates a local mountain heath flora dominated by ericaceous dwarf shrubs and graminids. The climate phase is interstadial or the beginning or end of an interglacial. The different diamictons also display different pollen spectra. During the last deglaciation the ice flow was from the north‐northeast. The second youngest system of drainage channels corresponds to ice flow from approximately west‐northwest. There are still older traces of separate deglaciation events from the east and north. A frozen bed is interpreted to have been the standard basal regime for the last ice sheets to cover the Transtrand Mountains.