Relative surface age-dating of rock glacier systems near Holar in Hjaltadalur, northern Iceland

Schmidt-hammer rebound values and photogrammetric measurements of surface displacement were used to date two active polymorphic (high-altitude) and two relict monomorphic (low-altitude) rock glaciers near Holar in Hjaltadalur, Trollaskagi peninsula, northern Iceland (65 degrees 40' N, 19 degrees 00' W). Both low-altitude rock glaciers are of Late Weichselian or Preboreal origin (ca. 10.3-9.2 k yr BP) with minor later reshaping until the early Neoglacial period ('Vatnsdalur I'; ca. 5.2 k yr BP). Both high-altitude rock glaciers consist of an upper lobe overriding a lower lobe corresponding to initiation during different cool phases. The initiation of the lower lobes can possibly be attributed to the 'GH-8.2 event' (8.6-8.0 k cal. yr BP). They reached their terminal position at the end of the 'Vatnsdalur I' stage. The upper lobes of the high-altitude rock glaciers were initiated sometimes between the 'Vatnsdalur I' but substantially before the 'Vatnsdalur II' (ca. 3.0-3.2 k yr BP) stages and underwent modification during each following Holocene glacier expansion episode, culminating the last time in the Little Ice Age. Thus, it is suggested that similar looking rock glaciers occurring elsewhere in the Trollaskagi peninsula may have a similar complex history. Therefore, they may not be seen as rather simple landforms developed during the Little Ice Age. Copyright (C) 2007 John Wiley & Sons, Ltd.