Lichenometric dating: a commentary, in the light of some recent statistical studies

Bradwell, Tom

doi:10.1111/j.1468-0459.2009.00354.x

Cited by 48 publications

(47 citation statements)

References 67 publications

(61 reference statements)

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“…Interestingly, a study of over 12,000 thalli (Trenbirth and Matthews, this volume) has shown no clear evidence of growth rate decline in large (older) thalli (>50 mm), but does indicate that size plays a role in determining long-term growth rates in Rhizocarpon subgenus Rhizocarpon. These new results serve to underline the uncertainty still surrounding the growth curve of R. geographicum -in turn, this has important implications for the use of crustose areolate lichens in dating studies (Bradwell 2009;Armstrong and Bradwell, this volume;Trenbirth and Matthews, this volume).…”

Section: Introductionmentioning

confidence: 99%

Studies on the growth of rhizocarpon geographicum in nw scotland, and some implications for lichenometry

Bradwell

2010

Geografiska Annaler: Series A, Physical Geography

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Murchison House, British Geological Survey, Edinburgh, UK. Bradwell, T., 2010: Studies on the growth of Rhizocarpon geographicum in NWScotland, and some implications for lichenometry. Geogr. Ann., 92A (X): xx-xx. AbstractScotland, a maritime subpolar environment (55-60°N), has seen relatively few applications of lichenometry -even though it offers much potential. Perhaps surprisingly, direct measurements of Rhizocarpon geographicum growth rates in Scotland are so far lacking. This study reports on the growth of this crustose areolate species from 2 sites in Assynt, NW Scotland, between 2002 and 2009. Repeat photography of 23 non-competing thalli growing under identical environmental conditions on a single vertical surface over 5 years at Inchnadamph showed growth rates to be a function of size -with larger thalli (10-30 mm) growing significantly faster than the smallest thalli (<10 mm). Mean diametral growth rates in thalli >10mm are 0.67 mm yr -1 (s.d. = 0.16). Studies on a second vertical surface near Lochinver, over 7 years, yielded complex growth data on a more mature population of R. geographicum thalli (<50 mm in diameter). Here, mean diametral growth rates in the larger thalli (>10 mm) are slower (0.29 mm yr -1 ; s.d. = 0.12) than those at Inchnadamph. However, at this site, competition with other species rules out any meaningful comparison of growth rates between the 2 sites. Other growth processes were monitored over the 5 to 7-year study period, including hypothallus growth, areolae development, thallus coalescence, and inter-species competition -all have important implications for the use of Rhizocarpon species in lichenometry.

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Section: Introductionmentioning

confidence: 99%

Studies on the growth of rhizocarpon geographicum in nw scotland, and some implications for lichenometry

Bradwell

2010

Geografiska Annaler: Series A, Physical Geography

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“…However, this was questioned by McKinzey et al (2005) who critically assessed the historical data and concluded that LIA glacier maximum occurred in S Iceland in the late 18 th to early 19 th cen− tury. There are lichenometrical datings of the outermost Skálafellsjökull moraines pointing at the end of the 19 th century (Gordon and Sharp1983;Evans et al 1999), but other date the oldest moraines rather to the mid 19 th century (McKinzey et al 2004;, depending on the lichenometrical technique used, which is also discussed in Orwin et al (2008) andBradwell (2009). Moraines of Skálafellsjökull were in contact with moraines of Heinabergs− jökull and Fláajökull ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Rock surface micro−roughness, Schmidt hammer rebound and weathering rind thickness within LIA Skálafellsjökull foreland, SE Iceland

Dąbski¹

2014

Polish Polar Research

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Glacially abraded basaltic rock surfaces found within a Little Ice Age (LIA) fore− land of Skálafellsjökull (SE Iceland) were studied at eight sites of different age applying different weathering indices. They include surface micro−roughness parameters measured with the Handysurf E35−B electronic profilometer -a new tool in geomorphology, Schmidt hammer rebound (R−values) and weathering rind thickness. Values of these indices ob− tained from study sites exposed to subaerial weathering for more than ca. 80 years are sig− nificantly different than those from younger moraines closer to the glacier snout. Despite a wide scatter of readings within each study site, there is a significant correlation between the ages and the values of the indices. It is concluded that the micro−roughness parameters pro− vided by the Handysurf E35−B profilometer, Schmidt hammer R−values and weathering rind thickness are robust indices of rock surface deterioration rate in short time−scales. There is mounting evidence that rock surface undergoes relatively rapid weathering during first decades since deglaciation.

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“…3) for the construction of the lichen growth curve. Using the popular technique of the five largest thalli (5LL) (Bradwell 2009) we obtained an equation:…”

Section: Methodsmentioning

confidence: 99%

“…The contemporary shrinkage of the cryosphere is resulting in the recession of glaciers and the melting of permafrost on a global scale (Huber et al 2005), but has also led to a collaborative international effort to gather information on the contemporary behaviour of glaciers and rock glaciers (WGMS 2016;GAPHAZ 2017). This is accompanied by developments and discussions on dating (Hubbard & Glasser 2005), among which lichenometry and Schmidt hammer are very popular, but there are still different approaches to these methods (Winkler & Shakesby 1995;Evans et al 1999;Bradwell 2009;Dąbski 2007Dąbski , 2009Dąbski , 2014, which justifies our research in Kaunertal.…”

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Lichenometry and Schmidt hammer tests in the Kaunertal glacier foreland (Ötztal Alps) during the AMADEE-15 Mars Mission Simulation

Czempiński

Dąbski

2017

Miscellanea Geographica

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The aim of this article is to show the results of the lichenometrical and Schmidt hammer measurements performed in 2015 during the AMADEE-15 Mars Mission Simulation in the Ötztal Alps in order to test the capabilities of analogue astronauts and collect information on the geomorphic history of the study area since the Little Ice Age (LIA). The results obtained differ significantly from our expectations, which we attribute to differences in the field experience of participants and the astronauts' technical limitations in terms of mobility. However, the experiments proved that these methods are within the range of the astronauts' capabilities. Environmental factors, such as i) varied petrography, ii) varied number of thalli in test polygons, and iii) differences in topoclimatic conditions between the LIA moraine and the glacier front, further inhibited simple interpretation. The LIA maximum of the Kaunertal glacier occurred in AD 1850, and relative stabilization of the frontal part of the rock glacier occurred in AD 1711.

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Lichenometric dating: a commentary, in the light of some recent statistical studies

Cited by 48 publications

References 67 publications

Studies on the growth of rhizocarpon geographicum in nw scotland, and some implications for lichenometry

Studies on the growth of rhizocarpon geographicum in nw scotland, and some implications for lichenometry

Rock surface micro−roughness, Schmidt hammer rebound and weathering rind thickness within LIA Skálafellsjökull foreland, SE Iceland

Lichenometry and Schmidt hammer tests in the Kaunertal glacier foreland (Ötztal Alps) during the AMADEE-15 Mars Mission Simulation

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