Environmental changes in Northern Iceland since the Younger Dryas inferred from periglacial slope deposits

Abstract

The slopes in Northern Iceland show the widespread occurrence of solifluction features, indicative of an active periglacial environment due to annual mean temperatures around 3°C at sea level and seasonal soil frost. In order to reconstruct periods with active and inactive solifluction in the past we excavated 18 solifluction lobes for analysing the sediment sequences. Dating of the sediments was realised mainly by tephrochronology and 14C. The oldest solifluction layer could be dated to the Younger Dryas (YD), just after the deglaciation of Northern Iceland. The early to mid Holocene up to the deposition of Hekla 3 Tephra (~3 ka BP) is characterized by the accumulation of loess and tephra layers, which show no signs of secondary remobilisation or erosion, indicating stable slopes during the mid-Holocene climatic optimum (MCO). After the deposition of Hekla 3 Tephra and especially during the ‘Little Ice Age’ (LIA), solifluction reappeared in the profiles as a probable consequence of Neoglacial cooling. The results fit well with other proxies from Iceland (glacier variations, pollen), from North Atlantic marine cores and from Greenland ice records.