ABSTRACT
The basic principle underlying the use of lichens in dating is that if the relationship between the size and age of a given lichen taxon is known, then the age of a surface can be inferred from the size of the lichens present on it. The potential error in dating involved in aggregation is discussed by John L. Innes. The majority of lichenometric studies deal with taxa within the Rhizocarpon genus. Lichenometric dating methods assume that the size-age relationship of lichens on one deposit can be transferred to another deposit. Various problems surround the measurement of lichens for lichenometric purposes. The problems can be divided into those associated with measurement and those associated with sampling. Statistically, the subjective element in the measurement of the largest inscribed circles means that they are significantly less reproducible than longest axis measurements.
