Exercise and motivation

Wessels, W. H.

doi:10.4102/sajp.v39i3.888

Cited by 1 publication

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“…The bleaching of the sandstone through removal of iron(III) oxide probably assists the detachment of quartz grains and helps in the achievement of the weathering effects. 32 Optical and SEM studies 29 have demonstrated that lichen hyphae penetrate the sandstone pores to a depth of ¾1.5 mm below the surface with localized penetration to greater depths. Detachment of the quartz grains in the bioweathered substratum can result in an incorporation of˛-quartz into the lichen thalli.…”

Section: Resultsmentioning

confidence: 99%

Raman spectroscopic study of lichen‐assisted weathering of sandstone outcrops in the High Atlas Mountains, Morocco

Edwards

Holder

Seaward

et al. 2002

J Raman Spectroscopy

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The lichen Aspicilia caesiocinerea agg. colonizing Triassic sandstone rock outcrops between 1600 and 2800 m elevation in the High Atlas Mountains of Morocco has been observed to have some unusual growth strategies, including a probably unique undercutting of escarpments, which produce severe bioweathering of the substrata. Fourier transform Raman spectroscopy was applied to studies of lichen-substratal surface transects in order to identify key wavenumber spectral markers of the biogeological changes. The Raman data were combined with previously determined energy-dispersive x-ray spectral information on similar specimens to build up a picture of the survival strategy of the lichen in this seasonally arid environment, where temperature extremes on rock surfaces range between −20 and +60 • C and precipitation varies from rain and surface snow cover in winter to long periods of drought in summer.

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Section: Resultsmentioning

confidence: 99%