The Somerset Shale Member (Salem Limestone) of Kentucky: The Macrofauna

by Don R. Chesnut (chesnut<at>uky.edu)
©DRC 2014
Introduction

The Mississippian-age Somerset Shale Member is generally a highly fossiliferous shale found at the base of the Salem Limestone. The shale member was named by Charles Butts in 1922 for outcrops near Somerset, Pulaski County, Kentucky. Although discontinuous, the Somerset Shale separates the Warsaw Limestone below and the Salem Limestone above. The Somerset is found in south-central Kentucky, but equivalent shale beds may be found in Indiana, Illinois and Tennessee. The Somerset Shale is age equivalent to the Meramec of the Mid-Continent region of the United States and mid-Visťan of Europe, most likely the Holkerian of Britain, the Livian of Belgium and the Tulsky of Russia (Greb and Chesnut, 2009).

The Somerset Shale is laterally correlative with the Science Hill Sandstone which is found in Rockcastle and adjacent counties in Kentucky. The Science Hill was probably a proximal-subaqueous-deltaic deposit whereas the Somerset Shale was a more distal deltaic muddy deposit to the west and south of the sandstone.

More details and history about the Somerset Shale can be found in Feldman (1984, 1987, 1989).

Macrofauna

Identified macrofauna from the Somerset Shale include vertebrates, echinoderms, mollusks, brachiopods, bryozoans, cnidarians, poriferans and arthropods. Most abundant are the echinoderms, brachiopods and bryozoans. The crinoid Dichocrinus simplex, the blastoid Pentremites conoideus, the brachiopods Cleiothyridina and Composita as well as fenestellid and ramose bryozoans are especially abundant. See the following categories for more information.

References