Map lichen

Rhizocarpon geographicum
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Lecanorales
Family:	Rhizocarpaceae
Genus:	Rhizocarpon
Species:	R. geographicum
Binomial name
Rhizocarpon geographicum (L.) DC.

The map lichen is a species of lichen, Rhizocarpon geographicum, which grows on rocks in mountainous areas of low air pollution. Each lichen is a flat patch bordered by a black line of spores. These patches grow adjacent to each other, leading to the appearance of a map or a patchwork field.

Map lichen is a lichen widely used by climatologists in determining the relative age of deposits, e.g. moraine systems, thus revealing evidence of glacial advances. The process is termed lichenometry.

Lichenometry is based on the assumption that the largest lichen growing on a rock is the oldest individual. If the growth rate is known, the maximum lichen size will give a minimum age for when this rock was deposited.

Growth rates for different areas and species can be obtained by measuring maximum lichen sizes on substrates of known age, such as gravestones, historic or prehistoric rock buildings, or moraines of known age (e.g. those deposited during the Little Ice Age).

Distribution

This lichen species is broadly distributed and may be found in most cold areas with exposed rock surfaces. The North American range includes the Sierra Nevada^[1] and northern Boreal forests of Canada, Greenland, Iceland Fennoscandia and Siberia.^[2] In the tropics it only occurs at high altitudes such as the Andes of Peru and Colombia. Further south the Map lichen is found broadly across Patagonia^{[citation needed]}, in Falkland Islands, the sub Antarctic islands and the Antarctic Peninsula.^[3]

Outer space

In an experiment, this lichen species was placed in a capsule and launched into space. The capsule was opened, exposing the lichen to space conditions for 15 days before being brought back down to Earth, where it showed minimal changes or damage.^{[citation needed]}

See also

• Extremophile

References

• C. Michael Hogan. 2008. Black Spruce: Picea mariana, GlobalTwitcher.com, ed. Nicklas Stromberg
• Tracy Irwin Storer, Robert Leslie Usinger and David Lukas. 2004. Sierra Nevada Natural History,, 2nd ed, University of California Press, ISBN 0520240960, 9780520240964 439 pages

Line notes

1. ^ Tracy Irwin Storer, Robert Leslie Usinger and David Lukas. 2004
2. ^ C. Michael Hogan. 2008
3. ^ Global Biodiversity Information Facility