A comprehensive exposure-age dating approach to interpreting complex glacial and periglacial landscapes: the landscape mosaic of Alnesdalen, a Norwegian alpine drainage basin

Our aim was to use two exposure dating techniques in combination to understand the 39 age and development of the full complement of glacial and periglacial landforms in 40 the Alnesdalen drainage basin, southern Norway. This required the development of a 41 comprehensive, landscape-scale approach based on 32 10Be dates from 9 landforms 42 and 121 Schmidt-hammer dates from 106 landforms, which identified a palimpsest 43 landscape consisting of a mosaic of landforms of different ages. The approach enabled 44 a spatial and temporal reconstruction of Late Glacial and Holocene glacial variations, 45 and a deeper understanding of the periglacial, paraglacial, and paraperiglacial 46 response of the landscape to environmental change. 47 Results suggest that the whole of the Alnesdalen drainage basin was ice48 covered by the Scandinavian Ice Sheet at the Last Glacial Maximum and that 49 deglaciation of the valley sides and floors occurred during the Bölling-Allerød 50 Interstadial (~14.6–12.9 ka). Dated ice-marginal moraines establish the limits of the 51 Scandinavian Ice Sheet and of local glaciers during the Younger Dryas (~12.9–11.7 52 ka). Glacier extent at the maxima of the Early Holocene ‘Erdalen Event’ (~10.2 ka) 53 and the Late Holocene ‘Little Ice Age’ (~0.3 ka) is clarified. The periglacial response 54 to environmental change was dominated by paraglacial processes. In the in the 55 Bölling-Allerød Interstadial, large rock-slope failures were activated and talus slopes, 56 pronival ramparts, snow-avalanche fans, large-scale patterned ground, boulder fields 57 and boulder pavements began to form. Permafrost aggradation during the Younger 58 Dryas may have led to the formation of a short-lived rock glacier. Large-scale 59 patterned ground, boulder fields and boulder pavements became inactive in a 60 seasonal-frost climate before the onset of the Early Holocene Thermal Maximum. The 61 wide range of Holocene exposure ages from periglacial landforms with diachronous 62 surfaces, including snow-avalanche fans, talus slopes and pronival ramparts, indicate 63 low-levels of periglacial activity throughout a relatively benign Holocene.