Abstract

Ancient environments may be interpreted, at least in part, from primary structures in sedimentary rocks. Because such structures are largely developed during deposition, they provide information on the processes involved and on the general geologic and climatic setting. Unfortunately, many sedimentary structures are poorly understood; numerous data are required from the observation of modern sediments and of controlled experiments before positive conclusions can be drawn concerning rock genesis.

Stratification and cross-stratification representing a series of types are described with reference to environments in which they are known to have developed. Some of these structures are typical of more than one environment; other structures are represented by two or more varieties in a single environment. Thus, information on natural combinations or associations of structures is especially valuable for paleoecological interpretation.