The Younger Dryas Main Line on Leka, Norway, as determined from a high resolution digital elevation model derived from airborne LiDAR data

• The Younger Dryas shoreline on Leka is examined by the use of airborne LiDAR data.
• Mechanical abrasion by sea–ice and frost shattering is found vital during formation.
• Platform morphology and dimensions vary with different influence of forming agents.
• Cliff degradation is found to be significantly raised during shoreline formation.
• The study sheds light on coastal landscape development in cold climate regimes.

The Main Line is a conspicuous late glacial erosive feature along parts of the Norwegian coastline. Although the shoreline has been much studied, the genesis of the ancient raised sea-level is still somewhat unaccounted for. In this study, the Main Line on Leka, Norway, is illuminated through a high resolution (1 m pixel size) digital elevation model (DEM) derived from airborne LiDAR data. The DEM allows a detailed mapping of the shoreline's dimensions and actual distribution and hence provides an improved foundation for interpreting the pronounced features. A new method for estimating cliff degradation during shoreline formation is presented. The Main Line is found from 106–112 m asl on Leka. Varying platform morphology across the island points to different shore-eroding mechanisms. The shoreline is thought to be developed through the interaction of sea–ice processes and freeze–thaw mechanisms, where the former agent is considered to be of particular importance where the platforms are most levelled. A bulge on the outermost part of the shoreline features is described for the first time and interpreted as a consequence of freeze-on plucking. Mean platform widths range from 9–29 m, while mean cliff degradation is estimated to be 140 m3 m− 1. By adapting the age span of Main Line formation reported elsewhere, maximum erosion rates over 1 Ma totals to 58 km. The study sheds light on the Main Line's potential as a reference level when assessing postglacial landscape development and highlights the significance of episodic erosional events in cold climate regimes.