A note on biological weathering on nunataks of the juneau icefield, Alaska

TLDR: In this article, it is suggested that biological weathering may be a major destructive mechanism of the granitic lithologies, caused by wetting and drying episodes, results in the surface flaking of the rock.

Abstract: Observations on a number of nunataks of the Juneau Icefield indicate that chasmolithic algae play a major role in the breakdown of granitic rock. Expansion and contraction of the algal mucilage, caused by wetting and drying episodes, results in the surface flaking of the rock. Available data suggest that the average mass of material lost per year from 1 m2 of rock could be as high as 562 g. It is suggested that biological weathering may be a major destructive mechanism of the granitic lithologies. Des observations sur plusieurs nunataks du glacier Juneau indiquent que des algues chasmolithiques jouent un rǒle capital dans la rupture des roches granitiques. L'expansion et la contraction du mucilage algaire, dues a des periodes de secheresse et d'humidite entrainet la detachement de plaques superficielles de roche. Les donnees disponibles suggerent que la masse de materiau perdue par an sur une surface de 1 m2 de roche peut atteindre une valeur aussi elevee que 562 g. Il est suggere que cette alteration biologique peut ětre un mecanisme de desagregation capital pour des roches granitiques.