Weathering Processes and Forms

Complex weathering in drylands: Implications of ‘stress’ history for rock debris breakdown and sediment release

“…However, despite considerable advances in our understanding of the modis operandi and efficacy of individual weathering mechanisms under controlled laboratory conditions, these findings have rarely been translated to conditions and weathering forms in the natural environment. As Smith (1994) rightly comments, "weathering studies are more characterised by uncertainties and gaps in knowledge… (being) …not a question of what we know about desert weathering but what we do not know…" (p.39).…”

Response of concrete to accelerated physical salt attack exposure

“…This crystallization pressure depends on the pore size where higher pressure is created in smaller (micro) pores [9]. There are several factors affecting the salt crystallization damage in porous building materials including salt type and concentration, hydration phase transformation of the salt, evaporation rate, surface tension, vapor pressure, environmental conditions, and properties of the pore structure [2,3,10]. For instance, the conversion of anhydrous sodium sulfate (thenardite, Na 2 SO 4 ) to the hydrous (mirabilite, Na 2 SO 4 ·10H 2 O) form is associated with 314% volumetric expansion, which aggravates the damage of concrete compared to other salts [2].…”

Advances in permafrost and periglacial research in Antarctica: A review

“…More recently, the biochemical action of lichens has been stressed also for its effect of 'rock bioprotection' (Carter and Viles, 2005;Guglielmin et al, 2011b). Guglielmin et al (2011b) demonstrate that lichen colonization contributes to the hardening of the external surface of the roof of tafoni developing on granite of the North Victoria Land, as already suggested for sandstones in hot deserts in Southern Jordan (Viles and Goudie, 2004;Smith, 2009). Cannone et al (2008) analyzing the soil at several sites along a latitudinal transect between 73°and 77°S did not find any significant correlations or relationships in soil properties, active layer depth and correlated vegetation across the climate gradient because microclimatic conditions and parent material appear to be more effective than the regional climate gradient.…”