Transgression, regression and fossil community succession

Abstract

Recent paleoecological studies emphasized the recognition of successional stages of level-bottom communities, but have neglected to point out techniques for distinguishing succession within a fossil community from the temporal and spatial replacement of one fossil community by another. The physical integrity of a marine level-bottom community is discernible, in most instances, through careful temporal and spatial study, and one community may be distinguished from another by judicious application application of the end-member concept Community boundaries are only as distinct as the associated environmental stress gradient. Of 1st-order significance in understanding fossil community succession and replacement is appreciation of the basic asymmetry of the community dynamics involved in transgression-regression events. Of 2nd-order importance is appreciation of the nature of the onshore-offshore environmental stress gradient, which, in turn, is controlled by the physical setting of transgression-regression (e.g., progradation versus eustatic control; high topographic relief vs. low topographic relief, etc.). The application of the preceding concepts is shown by detailed study of community succession and replacement in [Chonetinella-Septopora community] the Cambridge Limestone (Upper Pennsylvanian), Guernsey County, Ohio [USA].