ABSTRACT With waterfalls and the deepest gorge in Pennsylvania, Ohiopyle State Park provides opportunities to observe a variety of habitats and three-dimensional (3-D) exposures of the Pennsylvanian sandstone most responsible for shaping Laurel Highlands landscapes. Evidence for the relationship between bedrock, ancient climates, and the landscape can be observed at some of the most scenic natural features of the park: Baughman Rock Overlook, Cucumber Falls, Ohiopyle Falls, Meadow Run Waterslide and Cascades, and Youghiogheny River Entrance Rapid. Channel azimuths and lateral variations in thickness of upper Pottsville fluvial/deltaic sandstone suggest that deposition was influenced by deformation of this part of the Allegheny Plateau during the Alleghanian orogeny. Geologic features of Pottsville sandstone outcrops include a 10-m- (~33-ft-) long Lepidodendron fossil and a 3-D exposure of a meter-high Pennsylvanian subaqueous sand dune and scour pit. Cosmogenic age dating has indicated very slow erosion of hard sandstone in an upland location at Turtlehead Rock and informed estimation of Pleistocene/Holocene waterfall retreat rates of Ohiopyle and Cucumber Falls. Bedrock exposures supporting scour habitats along the Youghiogheny River occur only in a limited area of Youghiogheny Gorge where knickpoint migration and bedrock erosion were relatively recent. Geologic factors, including locations of major tributaries, development of bars that constrict river flow, and proximity of Homewood sandstone outcrops as sources of boulder obstacles in the river, contributed to the class, location, and nature of whitewater rapids in the lower Youghiogheny River.

The Pittsburgh, Redstone, and Sewickley coal beds all occur in the Late Pennsylvanian Pittsburgh Formation of the Monongahela Group in the northern Appalachian Basin. The goal of this study is to compare and contrast the palynology, petrography, and geochemistry of the three coals, specifically with regard to mire formation, and the resulting impacts on coal composition and occurrence. Comparisons between thick (>1.0 m) and thin (<0.3 m) columns of each coal bed are made as well to document any changes that occur between more central and more peripheral areas of the three paleomires. The Pittsburgh coal bed, which is thick (>1m) and continuous over a very large area (over 17,800 km 2 ), consists of a rider coal zone (several benches of coal intercalated with clastic partings) and a main coal. The main coal contains two widespread bone coal, fusain, and carbonaceous shale partings that divide it into three parts: the breast coal at the top, the brick coal in the middle, and the bottom coal at the base. Thymospora thiessenii , a type of tree fern spore, is exceptionally abundant in the Pittsburgh coal and serves to distinguish it palynologically from the Redstone and Sewickley coal beds. Higher percentages of Crassispora kosankei (produced by Sigillaria , a lycopod tree), gymnosperm pollen, and inertinite are found in association with one of the extensive partings, but not in the other. There is little compositional difference between the thin and thick Pittsburgh columns that were analyzed. The Redstone coal bed is co-dominated by tree fern and calamite spores and contains no Thymospora thiessenii . Rather, Laevigatosporites minimus , Punctatisporites minutus , and Punctatisporites parvipunctatus are the most common tree fern representatives in the Redstone coal. Endosporites globiformis , which does not occur in the Pittsburgh coal, is commonly found near the base of the coal bed, and in and around inorganic partings. In this respect, Endosporites mimics the distribution of Crassispora kosankei in the Pittsburgh coal. Small fern spores are also more abundant in the Redstone coal bed than they are in the Pittsburgh coal. Overall, the Redstone coal bed contains more vitrinite, ash, and sulfur than the Pittsburgh coal. The distribution of the Redstone coal is much more podlike, indicating strong paleotopographic control on its development. Compositionally, there are major differences between the thin and thick Redstone columns, with higher amounts of Endosporites globiformis , gymnosperm pollen, inertinite, ash, and sulfur occurring in the thin column. The Sewickley coal bed is palynologically similar to the Redstone coal in that it is co-dominated by tree fern and calamite spores, with elevated percentages of small fern spores. Tree fern species distribution is different, however, with Thymospora thiessenii and T. pseudothiessenii being more prevalent in the Sewickley. The distribution of Crassispora kosankei in the Sewickley coal bed is similar to that in the Pittsburgh coal, i.e., more abundant at the base of the bed and around inorganic partings. By contrast, Endosporites is only rarely seen in the Sewickley coal. The Sewickley is more laterally continuous than the Redstone coal, but not nearly as thick and continuous as the Pittsburgh coal. Overall, the vitrinite content of the Sewickley coal is between that of the Pittsburgh (lowest) and Redstone (highest). Ash yields and sulfur contents are typically higher than in the Pittsburgh or Redstone. The thin and thick Sewickley columns are palynologically and petrographically very similar; ash and sulfur are both higher in the thin column.

Bench samples from the Springfield (western Kentucky No. 9) coal bed have been analyzed for 25 major, minor, and trace elements, including Au and Pt, by instrumental and radiochemical neutron activation analyses. The elemental enrichment trend of this coal bed, compared with crustal abundances, is similar to the Pittsburgh coal bed. Except for Mn, all the other elements in the western Kentucky No. 9 coal have a larger or comparable range of variation when compared with the Pittsburgh bed. The coefficients of variation increase with decreasing concentrations, or remain constant and independent of concentrations. They could be used in evaluating the mode of occurrence of chemical elements. The abundance of the chemical elements, particularly those at trace concentrations, are believed to have several sources. There are quantities inherent from plant debris, those derived from coal-forming processes, and quantities added from or lost to enclosing rocks during ground-water processes. The quantities from each source are not easily determined, but their source can be approached through the use of elemental ratios of coherent pairs. Analytical data are compared to values interpolated from U.S. Geological Survey isochem maps. Among the eight elements compared, the content of Al, Cr, Na, and Sb appear to correlate well. Three kinds of elemental abundance variation can be recognized. These are regional, local, and in-bed variations. On the basis of study of elemental distributions within mine locations, five variation types are identified. Only types I and V can be contoured directly with simple channel sampling. Local variation of the elements should be assessed for other variation types and composite channel samples should be collected to draw meaningful regional distribution contours. For the purpose of bed identification, coherent triads are presented. The triad Al-La-Sc is the best in characterization of a bed. The triads Br-Cs-Na and Co-Ga-Th are not useful for bed fingerprinting, but they are probably useful to identify coal beds locally.