A new lichenometric dating curve for southeast Iceland

This paper presents a new lichenometric dating curve for southeast Iceland. The temporal framework for the curve is based on reliably dated surfaces c overing the last 270 years, making it the best constrained study of this na ture conducted in Iceland. The growth of lichen species within Rizocarpon S ection Rhizocarpon is non-linear over time, with large, (older) thalli appa rently growing more slowly. The linear 'growth' curves derived previously b y former authors working in Iceland represent only part of a curve which ha s an overall exponential form. Reasons for the non-linearity of the new dat ing curve are probably physiological, although climatic change over the las t three centuries cannot be ruled out, Use of linear 'growth' curves in Ice land is problematic overtime - spans of more than c, 80 years. Pre-20th cen tury moraines dated using a constant, linear relationship between lichen si ze and age Lire probably older than previously believed. Those moraines lic henometrically 'dated' to the second half of the 19th century in Iceland ma y actually pre-date this time by several decades (30-100 years), thus throw ing doubt on the exact timing of maximum glaciation during the 'Little Ice Age'.