Rock moisture data from Livingston Island (maritime antarctic) and implications for weathering processes

• Published in: Permafrost and Periglacial Processes
• Main Author: Hall, Kevin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1993
• Subjects: Antarc*; Antarctic; Livingston Island; Permafrost and Periglacial Processes
• Online Access: http://dx.doi.org/10.1002/ppp.3430040306; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.3430040306; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.3430040306

Abstract Rock moisture content was determined for rock samples on different aspects of rock outcrops on Livingston Island during a summer season. As a result of the dominant rainbearing northerly winds the southern aspect usually has rock moisture levels lower than the northern. The southern aspect, however, experiences high rock moisture levels during periods of snowmelt; snow accumulates on the southern, lee‐side of the rock outcrops. Wetting and drying events are more frequent on the northern exposure, although not as common as at a site open through the full 360°, while the southern aspect tends to experience continuous, low moisture levels with infrequent dry events. Contrary to earlier suggestions, freeze–thaw weathering does not appear to be a major factor during the summer. Although rock moisture levels are conducive to freeze–thaw, rock temperatures rarely go below 0°C. Rather, it appears that weathering due to wetting and drying may be more common on the northern aspects than was previously thought while chemical weathering is active on southerly aspects. Rock moisture levels may support rock damage due to segregation ice during the winter freeze when the rate of freezing is slowed by the overlying snow cover. Contrairement a ce qui a été suggéré précédemment, l'altération par gel‐dégel ne semble pas ětre, l'été, un facteur de désagrégation principal. Quoique les niveaux d'humidité soient favorables aux actions de gel‐dégel, les températures des roches y descendent rarement sous 0°C. Au contraire, il apparaǐt que l'altération due aux alternances sèchage / humidification doit ětre plus fréquente sur les versants exposés au nord, tandis que l'altération chimique serait surtout active sur les versants exposés au sud. Les niveaux d'humidité des roches peuvent engendrer une désagrégation due à la formation de glace de ségrégation pendant l'hiver parce que la vitesse de gel est ralentie par la couverture de neige.