Folk classification

The Folk classification is a technical descriptive classification of sedimentary rocks devised by Robert L. Folk, an influential sedimentary petrologist and Professor Emeritus at the University of Texas.Thin-section of an oosparite with calcitic ooids and sparry calcite cement; Carmel:Formation, Middle Jurassic, of southern Utah, USA.Thin section of a biopelsparite showing a geopetal structure consisting of peloid sediment and sparry calcite cement in a recrystallized bivalve shell; Bird Spring Formation (Carboniferous) of southern Nevada, USA.Bioclasts in an Ordovician biosparite; T = trilobite; E = echinoderm; Ordovician of southern Ohio, USA.BiomicriteMicriteSparDismicriteIntraspariteBroken surface of Brassfield Formation (Early Silurian, Ohio) showing coarse sparry cement. The Folk classification is a technical descriptive classification of sedimentary rocks devised by Robert L. Folk, an influential sedimentary petrologist and Professor Emeritus at the University of Texas.