The Importance of Sand in Earth Sciences

Abstract

Being a solid, sand can sustain shear stresses at rest but it can also undergo large plastic deformations without considerable change of its properties, behaving thus like a fluid. As a product of erosion, sand cannot be broken into parts because it is already a broken (‘clastic’) material. The pronounced deformability of sand gave rise not only to a large diversity of experimental investigations in Soil Mechanics but rendered also sand a model material for physical simulations of deformation processes of the earth crust: Sand box models serve to simulate not only folding and faulting processes of the earth crust but also processes of deformation of the earth mantle. There are also similarities between magma volcanism and the so-called sand boils or sand volcanoes that appear subsequent to liquefaction of water-saturated loose sand. The complex behaviour of sand is a permanent object of study not only by Soil Mechanics but —in recent time— also by Physics. In this paper, the ability of sand to model the behaviour of other geomaterials is elucidated and a new theoretical frame is presented to describe mathematically the behaviour of sand based on its asymptotic properties.