In connection with the preparation of coal-bed structure maps stratigraphic studies have been made based on the matching of drilling logs of a series of wells extending from the vicinity of Carlinville on the west to western Cumberland County on the east. Such studies reveal a lack of agreement with correlations based on the study of outcrops. The pattern of succession on the western margin of the basin produced by the spacing of important limestone and coal beds appears to be traceable into the central part of the basin, indicating that the surface beds in the central area are much younger than those on the margin. Such a conclusion is at variance with conclusions that have been recently reached by the study of outcrops independent of coal-bed structures. Such studies ha e resulted in correlations which require a conspicuous spreading between the prominent limestone beds as they approach the inner part of the basin, resulting in a marked departure from parallelism with coal bed No. 6 on the part of the higher limestones. The paper points out the need of further studies and elaborates the evidence on which surface correlations are based.