ABSTRACT The Cincinnati Arch region of Ohio, Kentucky, and Indiana is an icon of North American Paleozoic stratigraphy, as it exposes strata ranging from Ordovician to Pennsylvanian in age. In particular, the highly fossiliferous Ordovician, Silurian, and Middle Devonian successions have been extensively studied since the nineteenth century, and continue to serve as a crucial proving ground for new methods and models of biostratigraphy, chemostratigraphy, and sequence stratigraphy in mixed clasticcarbonate depositional settings. These strata are locally capped by Middle Devonian limestones with their own diverse fauna and unique depositional history. Outcrops near Louisville, Kentucky, provide an excellent opportunity to examine these strata firsthand and discuss sequence stratigraphy, chemostratigraphy, sedimentary environments, and paleoecology. A series of new roadcuts south of Mount Washington, Kentucky, exposes the lower to middle Richmondian Stage (Upper Ordovician, Cincinnatian) and presents a diverse suite of marine facies, from peritidal mudstones to offshore shoals, coral biostromes, and subtidal shales. These exposures are well suited for highlighting the revised sequence stratigraphy of the Cincinnatian Series, presented herein. Nearby outcrops also include much of the local Silurian succession, allowing an in-depth observation of Llandovery and Wenlock strata, including several chemostratigraphically important intervals that have improved regional and international correlation. Supplementary exposures east and north of Louisville provide context for subjacent and superjacent Ordovician-Silurian strata, as well as examples of lateral facies changes and unconformities. Additionally, the Falls of the Ohio at Clarksville, Indiana, features an exceptional outcrop of the overlying Middle Devonian succession, including an extensive and well-preserved biostrome of corals, sponges, and other marine fauna. These fossil beds, coupled with significant exposures in local quarries, are critical for understanding the paleoecology and stratigraphy of the Middle Devonian of the North American midcontinent.

Abstract This field guide focuses on key outcrops that highlight recent nomenclatorial changes of Early Silurian strata in western Ohio (e.g., Dayton Formation, Osgood Formation, Laurel Formation, Lewisburg Formation, Massie Formation, Euphemia Dolomite), as well as the Brassfield Formation and Springfield Dolomite. The field trip begins near the apex of the Cincinnati/Findlay Arch at a quarry in Ludlow Falls, Ohio, and ends at a more offshore position to the southeast, near Clifton, Ohio. Recent conodont biostratigraphic and δ 13 C carb chemostratigraphic data for many of those formations at the field trip localities clearly demonstrate coeval stratigraphic patterns present throughout western Ohio that were previously obscured due to prior inconsistent lithostratigraphic terminology and correlation. Those data also help to show important differences in stratigraphic patterns in western Ohio. Strata correlative to the Lee Creek Formation are recognized for the first time near the apex of the Cincinnati/Findlay Arch in western Ohio in West Milton, Ohio, and are tentatively identified as that formation. At the same locality the Dayton is shown to be completely absent, and the Osgood Formation overlies a thin unit tentatively identified as the Lee Creek Formation and underlying Brassfield Formation. The Springfield Dolomite at the Barrett Paving Materials Ludlow Quarry in Ludlow Falls, Ohio, contains trilobites of the Gravicalymene celebra Association, one of the most taxonomi-cally diverse and geographically widespread trilobite associations in the Silurian of North America. Pentamerid brachiopods occur with molts of Gravicalymene celebra in the Springfield there, suggesting an environmental complexity not seen elsewhere; pentamerids are not found in strata containing the Gravicalymene celebra Association in most other areas of the Midwest.

Abstract This volume, produced in conjunction with the GSA North-Central Section Meeting held in Dayton, Ohio, April 2012, has a mix of papers, ranging from stratigraphy, paleontology, and hydrogeology, to geomorphology, drainage basins, and building stones. The geographic spread of the chapters focuses mainly on an area bounded by those counties adjacent to Montgomery County, but also extends beyond-from Paulding County in the north to Georgetown, Kentucky, in the south. Topics include the Silurian stratigraphy of southwestern Ohio, drainage basins of the Mad River and Little Miami River, the relationship between geology and groundwater of the Inner Bluegrass Region, Kentucky (and its connection to the distilling and aging of bourbon), and the building stones of Dayton, as well as an introduction to the geology of the Dayton area.