Abstract The Silurian rocks of the Cincinnati Arch in Ohio, Kentucky, and Indiana have been studied for nearly two centuries. Compilation of data from these studies, combined with detailed analysis of nearly 20 continuous drill cores and remeasuring and resampling of more than 60 major outcrops, is the basis for a high-resolution sequence stratigraphic framework. Seven depositional sequences are assigned on the basis of through-going unconformities, which mirror those already recognized in the early Llandovery to early Ludlow of the northern Appalachian Basin. Revision of the conodont biostratigraphy for the Cincinnati Arch has produced results that both agree and disagree with the other lines of data implemented in the sequence stratigraphic depositional model. Biostratigraphic correlations between southern Ohio and the Niagara Falls area are largely in agreement with correlations based on other lines of data, as are correlations between west-central and western Ohio, southeastern Indiana, and northern Kentucky. However, correlations between southern and west-central Ohio show major areas of disagreement. Preliminary whole rock carbonate carbon isotope analyses in western-central Ohio show patterns roughly comparable to those documented in the Niagara region, Gotland, and elsewhere. Chemostratigraphic data that might resolve inconsistencies in the correlations between southern and west-central Ohio were not yet available at the time of publication.

Abstract Dayton, Tennessee, the site of the 1925 Scopes evolution trial, is surrounded by a rich natural museum of Paleozoic sedimentary rocks that exemplifies Earth history literacy principles, in accord with those identified in the Next Generation Science Standards. A guide for a loop drive from Chattanooga to Dayton and Sequatchie Valley combines a visit to the site of the trial, analyzing its lessons for science educators, with a tour of sites where, with minimal jargon, evidence for the following principles is demonstrated: Sedimentary structures such as mud cracks and crossbeds record processes similar to those that deposit sediment in modern environments. Strata can be divided into rock units recognized over great distances. Fossils and their modes of preservation document the history of life, and give evidence of past environments. A succession of thousands of feet of sedimentary rock records hundreds of specific changes in sediment supply, water depth, and climatic conditions. The fact that diverse environments near sea level are recorded in great thicknesses of rock is powerful evidence of slow gradual subsidence, as opposed to a single flooding event followed by rapid sedimentation. Recorded changes in sediment supply and water depth provide evidence of the rise and erosion of nearby land, as well as continual moderate fluctuations in sea level. Originally horizontal rock layers have been disturbed in systematic ways traced to specific past plate tectonic events. These concepts were developed, in part, to help find mineral resources, and they prove their predictive value daily, for example, in locating deeply buried petroleum.