Lichen as a dating tool
Some authors claim lichenometry can help to a precise reconstruction of landforms and geomorphic processes in Iceland, proposing yearly dating, others includes margin errors in their reconstructions, while some limit its use to generation identifications, refusing to overpass the nature of the gathered data and further interpretation.Finally, can lichenometry be a relatively accurate dating technique or rather an accurate relative dating tool in Iceland?Fruticose lichens have a mature branching structure and resemble little bushes or trees, or they can hang down from tree branches. Foliose and fruticose lichens grow faster than crustose ones.A method of estimating the age of a rock or other surface by measuring the diameters of lichens growing on it is called lichenometry.
Scientists carefully measure the body of a lichen, called a thallus, with rulers or calipers.
Hundreds of kinds of lichens exist, classed into three main growth form types.
All are slow-growing and long-lived, lasting hundreds or thousands of years.
Richard Armstrong of Aston University gives data that shows the map lichen has an early phase of increasing growth until the thallus is 2.5 to 4.5 cm (1 to 1.77 inches) in diameter. Lichens in the Canadian Rockies that are 3 inches wide are about 600 years old; Swedish lichens with 6-inch-wide thalli are about 1,600 years old.
Reindeer lichens have an initial growth-accumulation period of six to 25 years, during which the lichen increases in height every year.
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Crustose lichens usually live tightly attached to their growing surfaces on rocks, trees, soils or buildings.