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.

Abstract Late Cenozoic tectonics of the Eel River basin have been characterized by at least three distinctly different regimes which reflect increasing activity toward the present. Late Cenozoic sediments and structures in the Eel River basin region reflects these tectonics regimes and records the tectonic evolution of the region during the passage of the subducting Juan de Fuca-Gorda plate system. The earliest of the three tectonic regimes resulted in prolonged neogene landscape stability and generated the Klamath surface and saprolite, a regionally extensive paleo-landscape of low relief mantled by a profoundly developed weathering profile. In the late Pliocene the stability was replaced by relatively uniform regional subsidence, and a thick sedimentary fill accumulated in the Eel River Basin. Following the passage of the Blanco fracture zone strong northeast compression replaced the regional subsidence in the Eel River basin area and generated a broad fold and thrust belt within the accretionary wedge. Northeast dipping thrust faults and associated folds deformed the Eel River basin sediments and altered sedimentation pattern to local structurally controlled depocenters. Rates of crustal shortening within the fold and thrust belt accommodate most or all of the plate convergence at the southern end of the Cascadia subduction zone, and indicate the Gorda and North American plates are strongly coupled.

Abstract The objective of this field trip is to examine variability in stream systems in west-central Ohio at different time and space scales. Scales of study range from watershed changes over 10 3 –10 4 years as drainage networks are established during glacial retreat, to reach-scale changes in tributary streams in response to human impacts and land use change over 10 1 –10 2 years, to diurnal and event-driven changes in water quality over 10 –2 to 10 –3 years. Drainage network changes in the Little Miami River and Mad River systems occurred through stream capture and were dependent on the location of early meltwater channels relative to ice lobe position and relict bedrock topography. At the reach scale, channel morphology (width, depth, slope, shape, and pattern) is dependent on mean discharge of water and sediment to the reach. Tributary streams to the Little Miami River, Mad River, and Buck Creek illustrate the impact that historic changes in land use, water and sediment discharge, channelization, and straightening of stream reaches have had on channel morphology and vertical stability. At the cross-section scale, flow characteristics, including stream stage and physical water quality parameters (temperature, pH, specific conductivity, oxidation-reduction potential, dissolved oxygen, and turbidity), are being measured on Buck Creek and Beaver Creek. Though some characteristics change diurnally in response to internal stream processes, event-based changes in response to stormflow reflect source area contributions of runoff and sediment.