Gently folded rocks in the Pennsylvanian of Ohio, USA.

The light brown-colored bed near the bottom of the picture is the Lowellville Limestone. It is medium grayish to gray-brown on weathered surfaces and very dark gray to black on crack surfaces. The unit is moderately fossiliferous, dominated by brachiopods. A medium-sized plant stem was also observed at this locality. The rocks here are gently folded and minor normal faulting is also present - probably relaxational structures.

Above the Lowellville Limestone is a succession of dark-colored mudshale, here nicknamed the "Lowellville Shale", which consists of fissile to flaggy to non-flaggy, fossiliferous to sparsely fossiliferous, black calcareous shale. Observed fossils in this unit include Posidonia bivalves, Trepospira gastropods, crinoid stem columnals, straight-shelled nautiloid cephalopods, coiled cephalopods, plants, and horizontal burrows.

These rocks are part of the Pottsville Group, a Pennsylvanian-aged cyclothemic succession in eastern Ohio that contains nonmarine shales, marine shales, siltstones, sandstones, coals, marine limestones, and chert ("flint"). The lower Pottsville dates to the late Early Pennsylvanian. The upper part dates to the early Middle Pennsylvanian. The Lower-Middle Pennsylvanian boundary is apparently somewhere near the Boggs Member (?).

Stratigraphy: Lowellville Shale over the Lowellville Limestone, Pottsville Group, upper Lower Pennsylvanian