Original Research

Experimental strain analysis of Clarens Sandstone colonised by endolithic lichens

D. Wessels, D. Venter, W. Wessels, L. Wessels
Koedoe | Vol 38, No 2 | a313 | DOI: https://doi.org/10.4102/koedoe.v38i2.313 | © 1995 D. Wessels, D. Venter, W. Wessels, L. Wessels | This work is licensed under CC Attribution 4.0
Submitted: 26 August 1995 | Published: 26 August 1995

About the author(s)

D. Wessels, University of the North, South Africa
D. Venter, University of the North, South Africa
W. Wessels,, South Africa
L. Wessels, University of the North, South Africa

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Abstract

Endolithic lichens occur commonly on Clarens Sandstone in South Africa, where they significantly contribute to the weathering of sandstone by means of mechanical and chemical weathering processes. This preliminary investigation reports on the success- ful use of strain gauges in detecting strain differences between sandstone without epilithic lichens and sandstone colonised by the euendolithic lichen Lecidea aff. sarcogynoides Korb. Mechanical weathering, expressed as strain changes, in Clarens Sandstone was studied during the transition from relatively dry winter to wet summer conditions. Daily weathering of sandstone due to thermal expansion and contraction of colonised and uncolonised sandstone could be shown. Our results show that liquid water in sandstone enhances the mechanical weathering of uncolonised Clarens Sandstone while water in the gaseous phase enhances mechanical weathering of sandstone by euendolithic lichens.

Keywords

strain gauge, endolithic, sandstone, weathering, microclimate, lichen

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