The status of the ‘Little Ice Age’ in southern Norway: relative‐age dating of Neoglacial moraines with Schmidt hammer and lichenometry

Abstract

A Schmidt hammer was used in conjunction with lichenometry to examine the relative age of the outermost Neoglacial moraines in front of glaciers in the Jotunheimen mountains of southern Norway. Particular attention was directed at (1) the magnitude of the ‘Little Ice Age’ glacier expansion episode relative to any others of Neoglacial age, and (2) the potential and limitations of the Schmidt hammer in the context of Holocene glacial chronologies. Schmidt hammer R‐values were measured at 34 glaciers and the sizes of the lichen Rhizocarpon geographicum agg. at 80 glaciers. Unusually low R‐values and large lichens suggest the occurrence of pre‐ ‘Little lee Age’ Neoglacial moraines at only a small minority (< 10 %) of the sampled glaciers. The traditional model of relatively large southern Norwegian glaciers during the ‘Little Ice Age’ is substantiated and it is tentatively suggested that differences in climate or glacier type may account for a regional difference in the status of the ‘Little Ice Age’ between northern and southern Scandinavia. The incorporation of weathered boulders into ‘Little Ice Age’ moraines by glacier push mechanisms, and the altitudinally‐related variation in boulder surface textures, are identified as major sources of potential error in the use of the Schmidt hammer R‐values for relative‐age determination of Neoglacial surfaces.