Stabilization of friable sandstone surfaces in a desiccating, wind-abraded environment of south-central Utah by rock surface microorganisms

Wind abrasion has resulted in a number of interesting geologic features on the Colorado Plateau. Among these features is a wind-abraded groove and associated weathering pit located in south-central Utah. The groove has formed on the Navajo Sandstone which is friable and erodible due to the sparse interstitial clay and silica that cements the grains of quartz and feldspar. Examination of the groove suggests that the rock surfaces are temporarily stabilized through microbial growth via the formation of extracellular polymeric substances as well as filamentous growth by rock surface microorganisms. This contributes to the development of a durable surface crust that retards erosion by wind and water. Stabilization is evident by the pattern of undercut flutes found on sandstone surfaces inhabited by microorganisms and the absence of undercutting on surfaces not visibly inhabited by microbes. Culturing of the microbial consortium from the sandstone surface on loose sand allowed us to determine that the microbial community provides a resistance to a penetration force of 526 dynes cm−2. These findings appear to contradict the conventional geological and biological wisdom that microorganisms greatly accelerate the weathering of rock and therefore render the rock more susceptible to erosional agents