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Lichenometry
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<h2 id="scope-and-limitations">Scope and limitations</h2> <p>Lichenometry can provide dates for <a href="/facts/Glacial/alIAm38r">glacial</a> deposits in <a href="/facts/Tundra/BqC0AQ7u">tundra</a> environments, lake level changes, glacial <a href="/facts/Moraine/NUoWIpka">moraines</a>, <a href="/facts/Trim_lines/r7SI7PVU">trim lines</a>, palaeofloods,<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> rockfalls, seismic events associated with the rockfalls,<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> talus (<a href="/facts/Scree/HoLvQLjc">scree</a>) stabilization and former extent of <a href="/facts/Permafrost/SkFC7LMT">permafrost</a> or very persistent snow cover.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> It has also been explored as a tool in assessing the speed of <a href="/facts/Retreat_of_glaciers_since_1850/3RVRal9J">glacier retreat</a> due to <a href="/facts/Climate_change/rEN4BDE7">climate change</a>.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p><p>Among the potential problems of the technique are the difficulty of correctly identifying the species, the delay between exposure and colonization, the varying growth rates from region to region, growth rates not always being constant over time and depend uuon substrate texture and composition, the climate, and determining the lichen that is the largest.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p> <h2 id="methods">Methods</h2> <p>Several methods exist for dating surfaces with help of lichenometry; the most simple relies on a single largest lichen though other methods use more. There are also differences in the way the lichen is measured; some scientists suggest that the largest <a href="/facts/Diameter/6uNn4VmU">diameter</a> should be measured, but others prefer the diameter of the largest inscribed circle. A problem in dating lichens is the fact that several <a href="/facts/Thalli/4FbF7wmC">thalli</a> can fuse together, making several minor lichens appears as a larger one of older age.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> The lichenometrist Tom Bradwell has listed the following five method families as the principal ones into which most other methods can be classified: </p> <ul><li>Largest lichen (LL): When the single largest lichen of a species is used it means that the lichen that is oldest or grows in most favorable conditions is used to date the minimum age of the exposed surface. This was the original lichenometric from which others then developed or used as reference. Despite relying upon a single lichen this technique is praised for its simplicity and allows obtaining an image of the age of rock exposure while still in the field.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></li> <li>Largest five lichens (5LL): This method is a development of the LL and was developed in the 1970s to avoid reliance on one single potentially anomalous lichen. It has been proved that neither accuracy nor precision improves significantly by having more than five lichens.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></li> <li>Fixed-area largest lichen (FALL): This technique was initially specially designed for dating rockfalls and <a href="/facts/Talus_cone/HoLvQLjc">talus cones</a> with no uniform age of deposition. The largest <a href="/facts/Thallus/4FbF7wmC">thallus</a> in a unit area is measured. The sample areas are usually boulders with surfaces of about 1 m2.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></li> <li>Size-frequency approach (SF): The analysis of size and frequency of lichens was initially done in order to study lichen populations and preexisting thalli growing on surfaces, but has since been used as an effective absolute and relative dating method.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></li> <li>Lichen cover approach (LC): This method works with the premise of that the area covered by a single species will increase over time, and by measuring the total area percentage covered by a certain lichen species the age of exposure can be inferred.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a></li></ul> <h2 id="further-reading">Further reading</h2> <ul><li>Winchester, Vanessa (2023). <a href="https://doi.org/10.3390%2Fland12030611">"Lichenometric dating and its limitations and problems: a guide for practitioners"</a>. <i>Land</i>. 12 (3): 611. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.3390%2Fland12030611">10.3390/land12030611</a>.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Holocene climatic and glacial history of the central Sierra Nevada, California, R.R. Curry, pp. 1–47, 1969, Geological Society of America Special Paper, 123, S.A. Schumm and W.C. Bradley, eds., 1969 <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Lichens in relation to management issues in the Sierra Nevada national parks, McCune, B., J. Grenon, and E. Martin, L. Mutch, Sierra Nevada Network, Cooperative agreement CA9088A0008. Oregon State University, Corvallis, Oregon, and Sequoia and Kings Canyon National Parks, Three Rivers, California, [1] <a href="http://openjournals.wsu.edu/index.php/pnwfungi/article/view/1031" target="_blank">http://openjournals.wsu.edu/index.php/pnwfungi/article/view/1031</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Benedict, James B. (January 2009). "A Review of Lichenometric Dating and Its Applications to Archaeology". American Antiquity. 74 (1): 143–172. doi:10.1017/S0002731600047545. S2CID 83108496. <a href="/wiki/American_Antiquity" target="_blank">/wiki/American_Antiquity</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Sowers, J.M., Noller, J.S., and Lettis, W.R., eds., 1997, Dating and Earthquakes: Review of Quaternary Geochronology and its Application to Paleoseismology. U.S. Nuclear Regulatory Commission, NUREG/CR 5562. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Benedict, James B. (January 2009). "A Review of Lichenometric Dating and Its Applications to Archaeology". American Antiquity. 74 (1): 143–172. doi:10.1017/S0002731600047545. S2CID 83108496. <a href="/wiki/American_Antiquity" target="_blank">/wiki/American_Antiquity</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Innes, John L. "Lichenometry". Progress in Physical Geography. 9 (187). <a href="http://ppg.sagepub.com/cgi/reprint/9/2/187" target="_blank">http://ppg.sagepub.com/cgi/reprint/9/2/187</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Armstrong, R. A. (August 1983). "Growth Curve of the Lichen Rhizocarpon Geographicum". New Phytologist. 94 (4): 619–622. doi:10.1111/j.1469-8137.1983.tb04870.x. ISSN 0028-646X. <a href="https://doi.org/10.1111%2Fj.1469-8137.1983.tb04870.x" target="_blank">https://doi.org/10.1111%2Fj.1469-8137.1983.tb04870.x</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Beschel, R. (1950). "Flechten als Altersmasstab rezenter Moränen". Zeitschrift für Gletscherkunde und Glazialgeologie. 1: 152–161. <a href="/wiki/Roland_Beschel" target="_blank">/wiki/Roland_Beschel</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Lichenometry". Archived from the original on 2008-08-23. Retrieved 2009-02-25. <a href="https://web.archive.org/web/20080823052446/http://mc2.vicnet.net.au/home/date/web/lich.html" target="_blank">https://web.archive.org/web/20080823052446/http://mc2.vicnet.net.au/home/date/web/lich.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>William Allen (2013) https://www.scribd.com/doc/156523915/A-Lichenometric-Study-of-Palaeofloods-in-the-Brecon-Beacons <a href="https://www.scribd.com/doc/156523915/A-Lichenometric-Study-of-Palaeofloods-in-the-Brecon-Beacons" target="_blank">https://www.scribd.com/doc/156523915/A-Lichenometric-Study-of-Palaeofloods-in-the-Brecon-Beacons</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Lichens in relation to management issues in the Sierra Nevada national parks, McCune, B., J. Grenon, and E. Martin, L. Mutch, Sierra Nevada Network, Cooperative agreement CA9088A0008. Oregon State University, Corvallis, Oregon, and Sequoia and Kings Canyon National Parks, Three Rivers, California, [1] <a href="http://openjournals.wsu.edu/index.php/pnwfungi/article/view/1031" target="_blank">http://openjournals.wsu.edu/index.php/pnwfungi/article/view/1031</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Solomina, Olga; Ivanov, Mikhail; Bradwell, Tom (2010). "Lichenometric studies on moraines in the Polar Urals". Geografiska Annaler: Series A, Physical Geography. 92 (1): 81–99. JSTOR 40661039. <a href="/wiki/JSTOR_(identifier)" target="_blank">/wiki/JSTOR_(identifier)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Richard Armstrong (September 2004). "Lichens, Lichenometry, and Global Warming" (PDF). Microbiologist: 32–35. Archived from the original (PDF) on 2009-02-25. <a href="https://web.archive.org/web/20090225044120/http://www.sfam.org.uk/pdf/features/lichens.pdf" target="_blank">https://web.archive.org/web/20090225044120/http://www.sfam.org.uk/pdf/features/lichens.pdf</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Innes, John L. "Lichenometry". Progress in Physical Geography. 9 (187). <a href="http://ppg.sagepub.com/cgi/reprint/9/2/187" target="_blank">http://ppg.sagepub.com/cgi/reprint/9/2/187</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Lichen, Lichenometry and Global Warming Archived 2011-07-08 at the Wayback Machine <a href="http://www.blackwellpublishing.com:443/Microbiology/pdfs/lichens.pdf" target="_blank">http://www.blackwellpublishing.com:443/Microbiology/pdfs/lichens.pdf</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Bradwell, Tom (2009). "Lichenometric Dating: A commentary in the light of some recent statistical studies". Geografiska Annaler. <a href="/wiki/Geografiska_Annaler" target="_blank">/wiki/Geografiska_Annaler</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Bradwell, Tom (2009). "Lichenometric Dating: A commentary in the light of some recent statistical studies". Geografiska Annaler. <a href="/wiki/Geografiska_Annaler" target="_blank">/wiki/Geografiska_Annaler</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Bradwell, Tom (2009). "Lichenometric Dating: A commentary in the light of some recent statistical studies". Geografiska Annaler. <a href="/wiki/Geografiska_Annaler" target="_blank">/wiki/Geografiska_Annaler</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Bradwell, Tom (2009). "Lichenometric Dating: A commentary in the light of some recent statistical studies". Geografiska Annaler. <a href="/wiki/Geografiska_Annaler" target="_blank">/wiki/Geografiska_Annaler</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Bradwell, Tom (2009). "Lichenometric Dating: A commentary in the light of some recent statistical studies". Geografiska Annaler. <a href="/wiki/Geografiska_Annaler" target="_blank">/wiki/Geografiska_Annaler</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> </ol>