REVISITING THE DEVONIAN-CARBONIFEROUS BOUNDARY INTERVAL IN THE U.S. MIDCONTINENT: TYPE KINDERHOOKIAN AREA OF ILLINOIS, MISSOURI, AND IOWA
The McCraney Formation of the classic Kinderhookian succession was established by Moore for the limestone bluffs on McCraney Creek near Kinderhook, Illinois. In southeast Iowa, the McCraney consists of alternating beds of lithographic limestone and fine crystalline dolomite. The Iowa McCraney outcrops are very similar in appearance to the Louisiana Formation, whose type area is near the town of Louisiana in northeastern Missouri. The McCraney and the Louisiana underlie parts of SE Iowa, NE Missouri, and NW Illinois. Both typically underlie a siltstone unit or are unconformably overlain by the Burlington Formation. Both overlie siltstone or shale units of the Upper Devonian Series. Although both units share some of the same brachiopod fauna, the Protognathodus kockeli Zone fauna of the Louisiana is older than the conodont fauna with distinctive Siphonodella in the Iowa McCraney. Stratigraphic distinction of these two units has been confounded by the fact that there are no outcrops where both units are present in direct sequence. Furthermore, Witzke suggested that the ‘McCraney’ in SE Iowa may not be the same as the type McCraney of Illinois and could be a lithologically similar unit of a different age that is yet to be formally recognized.