Preliminary results from the lichenometric study of the Nautardلlur rock glacier, Trِllaskagi, northern Iceland

Preliminary results from the lichenometric dating studies undertaken using the collective lichen “species” Rhizocarpon geographicum sensu lato are presented and applied to the establishment of a rock glacier developmental chronology for the Nautardálur rock glacier, Tröllaskagi, northern Iceland. Absolute dates are tentatively postulated based on the application of the largest lichen thalli diameters to a regional Trollaskagi R. geographicum s.l. growth rate of 40 mm/ 100 yr. ometric ages on the Nautardálur rock glacier range over a continuum from approximately 200 yr BP to present. A time-frame suggestive of rock glacier development initiated during or immediately after the Little Ice Age, when a small come glacier was inundated with rock debris which formed an insulating “skin” over the ice and permitted its preservation until present. Lichenometric dating therefore provides an independent means of dating rock glacier deposits which agrees well with relative ages postulated by other palaeo-reconstructional methods.