Concepts of Facies

Stratigraphic facies was recognized, defined, and named by Gressly in 1838. Before the end of the nineteenth century the concept of facies became firmly established, through the works of Mojsisovics, Renevier, and Walther, as referring to the sum of lithologic and paleontologic characteristics of a sedimentary rock from which its origin and the environment of its formation may be inferred. Similar or identical rock types have isopic facies, different rock types heteropic facies. Facies changes must be studied in horizontal as well as vertical direction, with the aim of reconstructing changes of environment in space and time. Genetically interconnected isochronous facies form facies tracts; genetically interconnected facies tracts form facies families. Heteropic facies in ertical succession form facies sequences. When used to designate major stratigraphic sequences occurring in certain geographic, oceanographic, or inferred tectonic environments, the term facies loses its descriptive objectivity. Non-stratigraphic uses of facies are discussed. Recent American facies terminology is discussed in terms of earlier established European terminology. Facies and as used in ecology differ importantly from stratigraphic facies and biofacies. Rock characteristics now referred to as biofacies in stratigraphy should be called paleontologic facies. Finally, some modern Russian facies literature is reviewed.