The Orravatnsrustir palsa site in Central Iceland-Palsas in an aeolian sedimentation environment

The Orravatnsrustir palsa site, located north of the Hofsjokull glacier in Central Iceland, has well developed palsas located in a valley-like depression at 710-715 m a.s.l. and stands in remarkable contrast to the surrounding desert-like highland plateau. The purpose of this paper is to give an overview of the Orravatnsrustir palsa site, geographic distribution and geomorphic statistics related to size and permafrost thicknesses of the palsas, including recent changes. Icelandic palsas exhibit characteristics of both organic palsas and lithalsa (frozen mineral soil). They are subjected to intense aeolian deposition of volcanic materials. The palsas are often 40-200 cm high, with a 40-80 cm thick active layer and permafrost reaching more than 5 m depth. Measurements of the size of the palsas and the thickness of the active layer which started in 2001 indicate that their size is decreasing and the thickness of the active layer is increasing. These results are in agreement with the general warming trend which has occurred in Iceland during the last decade. (c) 2012 Elsevier B.V. All rights reserved.