Clay between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. Mixtures of sand, silt and less than 40% clay are called loam. Loam makes good soil and is used as a building material. Clay minerals typically form over long periods of time as a result of the gradual chemical weathering of rocks, usually silicate-bearing, by low concentrations of carbonic acid and other diluted solvents. These solvents, usually acidic, migrate through the weathering rock after
Granular material the pattern-forming behaviours have been possible to reproduce in computer simulations. There are two main computational approaches to such simulations, time-stepped and event-driven, the former being the most efficient for a higher density of the material and the motions of a lower intensity, and the latter for a lower density of the material and the motions of a higher intensity. Some beach sands, such as those of the aptly named Squeaky Beach, exhibit squeaking when walked upon. Some desert dunes are known to exhibit booming during avalanching or when their surface is otherwise disturbed. Granular materials discharged from silos produce