ODM2 Variable Name Controlled Vocabulary ODM2 Working Group A vocabulary for describing the name of Variables. Grain size Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. Wikipedia https://en.wikipedia.org/wiki/Grain_size Added to support Critical Zone Observatory (CZO) data use cases.