Towards harmony in stratigraphic classification

Abstract

Stratigraphic classification is the systematic zonation of the strata of the earth9s crust with reference to any of the many different properties or attributes which rock strata may possess. It is an essential step for us, both toward the scientific and philosophic understanding of the rocks of the earth9s crust and toward their economic utilization. This concept of stratigraphic classification is extremely simple, and offhand it is hard to see why there should be any problems other than the strictly geological ones involved in the accurate scientific identification of stratigraphic characters and the selection, tracing, and definition of units based on variations in these characters. That there are other problems, and even some degree of confusion and controversy, seems to result principally from the following: 1) Lack of a clear concept of what is being classified. 2) Lack of adequate standards of reference for specific stratigraphic units. 3) Attempts to zone strata according to 2 or more different characters using only one set of units. 4) Lack of precise and uniform terminology. 5) Proliferation of unnecessary terms. 6) Influence of preconceived notions on stratigraphic classification handed down from the early stages of the development of stratigraphy. 7) Intolerance by specialists in one field of stratigraphic classification toward potential contributions of other fields. Great progress is being made toward general agreement on principles of stratigraphic classification and toward uniformity of usage in terminology. The work of the International Subcommission on Stratigraphic Terminology, as well as that of the several national commissions on stratigraphic nomenclature is showing excellent results. Recent questionnaires distributed to stratigraphers throughout the world, as well as other samplings of thought and opinion, reveal a very encouraging trend toward harmony on points of stratigraphic classification and terminology which only a short time ago were confused by very diverse viewpoints. A summary of the conclusions arising from 75 replies to a recent world-wide questionnaire of the International Subcommission on Stratigraphic Terminology is particularly illuminating. Some areas of controversy still remain, but the goal of reasonably close international accord appears definitely attainable. An interesting variation in views on stratigraphic classification lies in the concept of the U.S.S.R. Stratigraphic Commission of a single kind of stratigraphic classification resulting in a single set of units based on natural stages in the development of the earth9s crust, in contrast to the multiple kinds of stratigraphic units to which most of the rest of the world appears to subscribe.