Attempted practical applications of existing classifications of sedimentary rocks commonly encounter difficulties and inconsistencies: (1) sediments normally unassociated during deposition are artificially grouped together; (2) inferences about environment, degree of tectonic influence, and other factors not everywhere legible in the rocks are required in differentiating major categories; (3) rocks of rare and common occurrence are given equal treatment; and (4) important rock types, such as shales and carbonates, are inadequately subdivided in contrast to attention accorded sandstone. The proposed classification is designed for rapid determination of sedimentary rocks using the binocular microscope. The system of identification proceeds in regular order from characteristics which are most readily recognized to those which require more critical examination. Examples of specific conglomerate, sandstone, shale, and limestone varieties are listed and are arranged in groups to indicate their associations.

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