Abstract The lower Wabash and Ohio River valleys have experienced seismicity throughout geologic time. The rocks and sediments in southern Indiana, southern Illinois, and western Kentucky provide records of these past seismic events in the form of various types of filled fractures. In the field these features occur either as downward penetrating, surface-filled fractures created by tectonic deformation or seismicity, or as upward penetrating liquefaction features such as clastic dikes and sills created by strong earthquakes. The fractures are widespread and abundant in many places, and are usually seen in natural exposures such as stream banks and less commonly in man-made excavations. In contrast, their causative faults are rarely observed. Thus, compared to searching for faults, the study of filled fractures is a useful and relatively inexpensive technique for assessing the seismic history of a region. The fractures discussed are clearly of seismic origin on the basis of morphology, sediment characteristics, regional patterns, and proximity to known faults. Further research is needed to determine whether additional types of features, which we discuss and examine in the field, can also serve as paleoseismic indicators.

Abstract This guidebook complements the field trips offered during the 42nd Annual Meeting of the GSA North-Central Section, held in Evansville, Indiana. Topics include analysis and correlation of Silurian depositional sequences across the Cincinnati Arch in Ohio, Kentucky, and Indiana; conodonts and Pennsylvanian stratigraphy in southwestern Indiana; relationships between tectonism, igneous activity, and fluorite mineralization within the Illinois-Kentucky Fluorite District; characteristics and origin of the highly eroded Pennsylvanian sandstones at the Garden of the Gods in Illinois; use of filled-fracture features as indicators of seismicity within the lower Wabash and Ohio River valleys; and hydrogeology of an abandoned mine site in Indiana, with applications to planning for disposal of coal-combustion products. Two chapters focus on the history of New Harmony, Indiana, which served as headquarters for the pioneering naturalists who worked to characterize and map this country's interior. Another chapter relates the history of Evansville to the availability and use of geologic materials, with discussions on the characteristics and origins of building stones, building techniques, and architectural styles. References to mining history, with respect to building stone, coal, and fluorite, are made throughout.

R- and Q-mode cluster analysis of data on the occurrence and distribution of 43 conodont species enables delineation in North America of warm-water Red River and Ohio Valley provinces during the Late Ordovician Velicuspis Chron, and suggests recognition of six major biofacies that represent a continuum from nearshore, shallow-water biotopes with numerous endemics to offshore, deeper-water biotopes characterized by more cosmopolitan species. Approximately coeval conodonts from Great Britain, Baltoscandia, and continental Europe are assignable to at least 36 taxa, which are less well known than those of equivalent age in North America but represent cold-water faunas whose Late Ordovician distribution and frequency of occurrence may be used to characterize British, Baltoscandic, and Mediterranean provinces, within which we recognize only three distinct biofacies. Only a third of the taxa in the Late Ordovician cold-water region are also represented in warm-water areas, where they characterize relatively deeper-water biofacies or have a distribution that indicates they were eurythermal cosmopolites. Late Ordovician conodonts are treated as components of warm- and cold-water pelagic faunas, not because their distribution demands that interpretation, but because the pelagic model is simpler than a benthic or nektobenthic one and squares readily with available distributional data.