An experimental study on the susceptibility of crusted surfaces to wind erosion: A comparison of the strength properties of biotic and salt crusts

Penetrometry has been employed in a number of studies investigating the strength of crusted sediments as related to their stability to particle impact in aeolian systems. Despite the early success of this procedure, questions remain concerning the effect of the angle of penetration, the role of fatigue, and the relative importance of the ultimate strength as compared to the elasticity of the crust. This paper reports on a series of penetrometer and wind tunnel experiments that consider these effects in the context of both salt and biotic crusts. The results demonstrate that the angle of penetration is not important but the density of penetrations is. The decreased strength observed with high densities of penetration, repeated loading, and continual impact in wind tunnel experiments provides further confirmation that sedimentary crusts progressively become weaker during mass transport events. The elasticity of the surface appears to be at least as important to consider as the ultimate strength. Although much stronger, the salt crusts were found to break down and erode sooner than biotic crusts in wind tunnel studies. The notable elasticity of biotic crusts appears to afford them some protection against abrasion. (c) 2005 Elsevier B.V. All rights reserved.