Desert varnish

Desert varnish

Problems in environmental geotechnology

Published in Hsai-Yang Fang, John L. Daniels, Introductory Geotechnical Engineering, 2017

Desert varnish: The uppermost layer of the soil profile (Fig. 16.5) on many desert rock surfaces is a thin, dark surface patina known as desert varnish. Most desert varnishes are very old, but some are formed recently. The causes and formation of desert varnish are still debated. Early geomorphologists thought that desert varnishes were caused by the evaporation process, which will carry iron (Fe) and manganese (Mn) from underlying rock layers. Some scientists have found evidence that in some desert varnishes, elements are scavenged and fixed by lichens and bacteria.

Rocky relationships: the petroglyphs of the Murujuga (Burrup Peninsula and Dampier Archipelago) in Western Australia

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Journal Information

Published in Australian Journal of Earth Sciences, 2019

E. R. Ramanaidou, L. C. Fonteneau

For the monitoring study that underpins this article, we were allowed to collect a small number of rock specimens to work on. Although this article interfaces the relationship between rocks, humans and birds within an archeological framework, it is fundamentally a geological paper that provides new information on the mineralogy, petrology, chemistry and spectroscopy of the weathering layer developed on both granophyre and gabbro. It will also show the impact of bird droppings associated with an increase in phosphorus and ‘desert varnish’ associated with an increase in manganese on the weathered layer as well as provide a novel technique to quantify the relative age of the petroglyphs.

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Problems in environmental geotechnology

Rocky relationships: the petroglyphs of the Murujuga (Burrup Peninsula and Dampier Archipelago) in Western Australia