Detailed geologic mapping has indicated that strata referred to as Drury Member of Caseyville Formation may actually lie entirely above what is mapped in the Goreville quad as the Pounds Sandstone Member, rather than below it. If this is true, author feels the Drury needs a major redefinition. Drury, as used in this report, follows the usage established by Nelson and others (1990). Drury is predominantly shale and siltstone, but the sandstones, are best exposed. One of these sandstones, the Dutchman Creek sandstone lentil, is relatively continuous and was mapped on the quad. It is an orthoquartzite, light to yellow tan that locally weathers to orange-yellow and commonly has orange-red Liesegang banding. The lentil is medium to thick bedded and typically trough cross-bedded. Occurs near the middle part of the Drury and forms ledges from 10 to 30 ft thick. Unit is shown as Middle Pennsylvanian (Morrowan). [Morrowan here considered to extend into the Middle Pennsylvanian.]

Source: GNU records (USGS DDS-6; Reston GNULEX).