R.C. MOORE'S PRONOUNCEMENTS ON GENETIC STRATIGRAPHY, SEQUENCES, AND CYCLIC SEDIMENTATION

Genetic Stratigraphy was proposed and practiced by R.C. Moore as early as the mid-1930s. Moore's concept and his work on sequences of deposition and erosion of sediments developed into sequence stratigraphy as promoted later by L.L. Sloss and the group at Northwestern University. Genetic stratigraphy is the grouping of rock sequences into like-related bundles separated by unconformities from systemetic to formational (mappable) size, but not based on a rock unit classification. The smallest genetic unit as understood by Moore was the cyclothem, a term proposed by J.M. Weller, composed of phases (or units) as envisioned by M.K. Elias, and arranged in a hierarchical grouping of the bundles. Rock classification is governed by a set of stratigraphic rules whereas a genetic grouping is based on interpretation by the investigator on origin and development of the genetic bundle. The two classifications serve different purposes but both have a distinct purpose. The major sequences as defined in North America better reflect significant episodes of geologic history of the continent than the classical rock column classification as developed in Europe.