The correlations of the formations of the Chester from Randolph County, Illinois, to Hancock County, Kentucky, are illustrated with a series of sample logs. Basal Pennsylvanian sands and shales rest unconformably on various Chester formations from the Menard to the Kinkaid. The Menard, Glen Dean, Hardinsburg, Golconda, and Cypress formations are shown to be continuous across the basin. An eastward thickening into the basin of the strata lying above the distinctive basal Paint Creek limestone and beneath the Golconda formation and a compensating eastward thinning of the strata between the basal Paint Creek limestone and the Ste. Genevieve are noted. The sandstones, shales, and thin limestones between the Paint Creek and the Ste. Genevieve are traced eastward into the deep art of the basin where they appear to grade laterally eastward into heavy limestones which some workers have considered to be of Ste. Genevieve age.