Correlations of Pennsylvanian Strata in Arkansas and Oklahoma Coal Fields

Abstract

Investigations in the Oklahoma and Arkansas coal fields have enabled the writers to establish definite correlations between the formations present in the two areas. These correlations differ considerably from those in current use, as will be pointed out in the following discussion. In 1899, Taff published a report on the geology of the McAlester-Lehigh coal field of Oklahoma and defined the formations of the southeastern Oklahoma coal fields as now recognized. These are, from oldest to youngest, the Hartshorne sandstone, McAlester shale, Savanna sandstone, and Boggy shale. The Hartshorne sandstone in the McAlester-Lehigh field averages about 250 feet in thickness with a unit of shale in the middle part that contains the Lower Hartshorne coal. The McAlester shale in that field averages about 2,000 feet in thickness and is made up largely of dark marine shale that includes the Upper Hartshorne coal near the base and several sandstone beds and the McAlester coal in the middle portion. The Savanna sandstone averages about 1,200 feet in thickness, is made up of about equal amounts of sandstone and shale, and contains the Cavanal coal near the middle. The Boggy shale is about 2,850 feet thick, is made up largely of shale that contains many thin sandstone beds and that contains in the lower portion the Lower and Upper Witteville coals. The formations of the McAlester district were traced eastward to the Arkansas state line by Taff and Adams. The locations of the formational boundaries near the state line, as shown on the map accompanying that report, agree very closely with the boundaries as mapped by the present writers in 1930 and 1931. The recent mapping by the writers of the formational boundaries and of all traceable units within the formations was done by plane-table traverses starting at the type localities of the formations and continuing eastward to the state line.