The terminology and the concepts of gypsum-rich soils

Many terms in earth sciences, and their underlying ideas, have been developed in temperate–humid countries. Both geological and climatic reasons cause gypsum-rich soils to occur in dry lands. Soil science has paid little attention to gypseous soils, and this limited knowledge is reflected in the direct loan of customary terms of soil science that can lead to misconceptions on the composition and behaviour of soils with large proportions of gypsum. Elements for discussion on the use of sundry terms about soils containing gypsum are presented here and some of their implicit assumptions discussed. Some generic terms are examined, as well as several expressions used by organizations devoted to soil survey and classification. The transformations occurring in gypseous soils are discussed, in particular the effects from exposure. The refinements herein proposed aim to help understand the role of gypsum in local and global earth-surface processes.