The two dominant lithofacies of the Sweetland Creek Shale of the New Albany Group in IL are indistinctly bedded, bioturbated, greenish-gray to grayish-green shale and thickly laminated olive-gray to olive-black shale. Interbedding of these two shales characterizes the unit. Recognized as a distinct formation primarily in the subsurface of central IL and in parts of southwestern IL. In western and north-central IL, the Sweetland Creek is mapped together with the overlying Grassy Creek Shale. Age is early to middle Late Devonian based on conodonts. In the outcrop area of southeastern IN, the Selmier Member of the New Albany Shale is the same age. However, in the subsurface of northern and western IL, most of the Sweetland Creek is at a higher stratigraphic position and is therefore younger than the Selmier. An arbitrary vertical cutoff separates the Sweetland Creek from the Selmier southeastern IL.

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