Abstract An integrated approach, involving nearly all available biostratigraphic data, event and sequence stratigraphy, has been utilized in correlation of the Middle Devonian (latest Eifelian–Givetian) Hamilton Group and equivalent strata in north-central North America. This approach permits high-resolution correlation of strata equivalent to the Oatka Creek (upper Marcellus), Skaneateles, Ludlowville and Moscow Formations from New York into sections bordering the Michigan Basin in Ontario, Canada, as well as southern Michigan, northern Ohio and Indiana, USA. Most member and submember-scale units, herein slightly redefined and interpreted as 3rd and 4th order sequences, respectively, and their bounding condensed beds can be correlated regionally. Moreover, many faunal patterns also persist across this region, which, together with sequence stratigraphy, provides a bridge for correlation into the Michigan Basin. The detailed stratigraphy presented herein permits a more-resolved understanding of far-field tectonics, eustasy and biotic responses during the Middle Devonian. Allocyclic processes, primarily eustasy, played a key role in generating persistent sedimentary cycles. Episodes of rapid mud sedimentation occurred over large areas of the cratonic interior, distal to Acadian source terrains. The major Algonquin–Findlay Arch, which presently separates the Michigan Basin from the Appalachian foreland basin, was not present during deposition of these strata. Conversely, a roughly north–south trending region, running approximately through present-day Cleveland, Ohio, was first a local subsiding area during late Eifelian–early Givetian time and then underwent topographic inversion to form a local arch at which upper Hamilton units were condensed and then bevelled during the later Givetian; we infer that this feature may represent a migrating forebulge. Finally, fossil biotas do not show strong partitioning into Appalachian and Michigan basin faunal subprovinces during the early Givetian, as there appears to have been no physical barrier to migration at least in the study area. However, Hamilton-equivalent strata in the most proximal portion of the Appalachian Basin do show a relatively minor admixture of typical Michigan Basin taxa with normal Hamilton forms.

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 The Battle of Gettysburg in south-central Pennsylvania was the largest ever fought on American soil and one of the most significant in its consequences. Moreover, more clearly than most, it demonstrates the roles which underlying geology and surface topography can play in military actions. Early Mesozoic happenings produced the rocks underlying and shaping the Gettysburg landscape, which influenced the flow of the battle and thereby impacted the course of American history. Integration of the battlefield’s geological and military aspects, however, has not yet been adequately presented in concise field-guide format, and so doing that is the intent of the present article. Inspired by Brown’s (1962) brief summary of the geology of the Gettysburg bat-tlefield, the present co-authors recently wrote a lengthy guidebook and reissued it for a 2006 Geological Society of America Annual Meeting field trip ( Inners et al., 2006 ). A shorter field guide was also needed for that trip that could be used by many other geologists afterwards; therefore, Cuffey condensed the long guidebook into the article here, assisted particularly by Inners and Fleeger, but drawing on all of the authors’ contributions as well.