Editing Lichen (section)

=== Lichenometry ===
{{Main|Lichenometry}}
[[File:Lichen forming a Hidden Mickey.jpg|thumb|left|Lichen grown in a [[Mickey Mouse]] shape]]
[[File:Lichen Mickey 13 years later.jpg|thumb|left|13 years later]]
Lichenometry is a technique used to determine the age of exposed rock surfaces based on the size of lichen thalli. Introduced by Beschel in the 1950s,<ref name=Beschel1950/> the technique has found many applications. it is used in [[archaeology]], [[palaeontology]], and [[geomorphology]]. It uses the presumed regular but slow rate of lichen growth to determine the [[Surface exposure dating|age of exposed rock]].<ref name=LSN/>{{rp|9}}<ref>Curry, R. R. (1969) "Holocene climatic and glacial history of the central Sierra Nevada, California", pp. 1–47, Geological Society of America Special Paper, 123, S. A. Schumm and W. C. Bradley, eds.</ref> Measuring the diameter (or other size measurement) of the largest lichen of a species on a rock surface indicates the length of time since the rock surface was first exposed. Lichen can be preserved on old rock faces for up to{{citation needed|date=August 2014}} 10,000 years, providing the maximum age limit of the technique, though it is most accurate (within 10% error) when applied to surfaces that have been exposed for less than 1,000 years.<ref>Sowers, J. M., Noller, J. S., and Lettis, W. R. (eds.) (1997) ''Dating and Earthquakes: Review of Quaternary Geochronology and its Application to Paleoseismology''. US Nuclear Regulatory Commission, NUREG/CR 5562.</ref> Lichenometry is especially useful for dating surfaces less than 500 years old, as [[radiocarbon dating]] techniques are less accurate over this period.<ref name="innes">{{cite journal |doi=10.1177/030913338500900202 |title=Lichenometry |journal=Progress in Physical Geography |volume=9 |issue=2 |page=187 |year=1985 |last1=Innes |first1=J. L.|bibcode=1985PrPG....9..187I |s2cid=220949784 }}</ref> The lichens most commonly used for lichenometry are those of the genera ''[[Rhizocarpon]]'' (e.g. the species ''[[Rhizocarpon geographicum]]'', map lichen) and ''[[Xanthoria]]''.