Tafoni weathering is an azonal process: Examples from Antarctica, Sardinia and Australia

Abstract

Cavernous weathering (tafoni) is described from coarse-grained granitic bedrock in Northern Victoria Land (Antarctica), northern Sardinia (Italy) and southwestern Australia. It also occurs elsewhere in the world and on other coarse-grained lithologies. The cause of this unusual in-situ flaking and granular disintegration is problematic. Azonal conditions appear to be: (1) the presence of salt, (2) aridity and (3) high evaporation and sublimation rates. Zonal (site-specific) considerations are: (1) snow may transport salts far inland in Antarctica and (2) epilithic and endolithic lichen growth may assist biological weathering in Sardinia and Antarctica. In stable landscapes of great antiquity, such as southwestern Australia, tafoni-like forms appear to have developed over millions of years; they suggest that salts in solution move slowly and continuously towards the surface where they evaporate. Combinations of these conditions result in tafoni in these different environments.