Correlation of Pennsylvanian formations of North America

The substance of this contribution is a comprehensive chart of Pennsylvanian rocks that undertakes to summarize present knowledge and judgment of classification and correlation of these Lat-Paleozoic strata, which most American geologists consider properly classifiable as a system. Evidence bearing on differentiation of major divisions and annotations explaining correlations are presented briefly. The correlation chart is Number 6 of a series planned and developed through efforts of the National Research Council Committee on Stratigraphy (Dunbar et al., 1942).