Location and Accessibility The rocks at this site are exposed along a road cut on the eastern side of Pennsylvania 61, 0.3 to 0.5 mi (0.4 to 0.8 km) south of Pottsville, Pennsylvania (Fig. 1), on the southern margin of the Southern Anthracite field where the Schuylkill River has cut a deep gap in Sharp Mountain. Parking is available at several places, but it is advantageous to begin at the southern end of the outcrop and walk up section.

Abstract The thickest and most laterally continuous upper Carboniferous molasse in the central Appalachians is located in the Southern Anthracite Field of northeastern Pennsylvania. Substantial deposits extend throughout northeastern Pennsylvania where >90% of the total anthracite (original reserves) in the United States and the thickest coal beds of the eastern United States are located. The abundance of and demand for this resource allowed the region to prosper in the nineteenth and twentieth centuries. In Pottsville, Pennsylvania, the exposed Upper Mississippian to Middle Pennsylvanian molasse reveals a progressive evolution from a semiarid alluvial plain to a semihumid alluvial plain to a humid alluvial plain. The anthracite beds occur and thicken with increased humid conditions. The progression is also exposed in Tamaqua, Pennsylvania, where convenient access to the underlying Lower Mississippian strata is available, thus providing a section of all Carboniferous formations in the region. Finally, in Lansford, Pennsylvania, a renovated deep anthracite mine illustrates the historical methods and working conditions that existed to extract the valuable resource and allow the region to flourish and fuel the Industrial Revolution.

Abstract Centralia is in Pennsylvania’s western middle anthracite field, a large synclinorium in Columbia and Schuylkill Counties. Centralia residents set fire to a landfill at the edge of town in 1962, thereby igniting the Buck Mountain coal bed. Laurel Run is in Pennsylvania’s northern anthracite field, on the northwest-dipping limb of the Wyoming Valley syncline. In 1915, a miner’s abandoned carbide lamp started a fire at Laurel Run, igniting the Red Ash, Top Red Ash, and Bottom Ross coal beds. The Centralia and Laurel Run fires are burning out of control. Subsidence and the venting of toxic gases have destroyed large sections of each community. Because the Centralia fire started in the hinge zone of an anticline separating two synclines in the Western Middle Field, it spread in four directions. The Laurel Run fire occurred on one limb of a syncline, limiting its spread to two directions. At Centralia, the steeper-dipping beds permitted the fire to reach a greater depth more rapidly than at Laurel Run. In addition, the point of origin and steeper dip at Centralia make this fire more difficult to control, even though only one coal bed is burning. A historical and sociological comparison of both communities shows that the people of Laurel Run had greater access to political power and more experience as a community in dealing with crises. Laurel Run secured more government support in combating the fire than Centralia did and so emerged from the fire as a more socially intact community. The present state of each fire further underscores how different geologic settings and social conditions can lead to different outcomes.

Abstract The underground mining of anthracite coal in the Llewellyn Formation (Middle Pennsylvanian) of Centralia, Pennsylvania began in the mid-1800s and lasted until 1933, as production declined and oil replaced coal as the fuel of choice for heating homes and businesses. Strip mining in the 1950s proved to be an unsuccessful competitor against oil as well as gas, also used as a heating fuel. Consequently, major mining operations in Centralia ended in 1962, followed by the transfer of mineral rights to the borough of Centralia and eventually to the state of Pennsylvania. The Centralia mine fire is a natural laboratory for studying coal fires from historical, scientific, and sociopolitical perspectives. The fire began in May 1962 when trash burning in an abandoned strip-mining cut used as an unregulated dump on the south limb of the Centralia syncline ignited the Buck Mountain coal bed. The fire then spread to mining tunnels beneath Centralia. Residents of Centralia were unable to develop a strategic plan with the U.S. Office of Surface Mining, the U.S. Bureau of Mines, and state agencies for controlling or extinguishing the Centralia mine fire. Several factors including the fire’s elusive nature, fractures that circulate air to burning anthracite in the subsurface, the inexperience of town officials in dealing with state and federal officials, and the expense involved led to this impasse. Forty-two million dollars was appropriated by the U.S. Congress between 1985 and 1991 for Pennsylvania to relocate the remaining residents and businesses of Centralia because of the risk of subsidence and pollution associated with the fire. Although most of Centralia’s residents took advantage of the buyout, some did not. The few remaining homes that have not been demolished and the land occupied by the lingering residents now belong to Pennsylvania in accordance with the state’s declaration of eminent domain in 1992. Centralia has become a wasteland with scorched woodlands engulfed in minefire emissions. Forty-five organic and inorganic compounds were identified including the greenhouse gases methane and carbon dioxide and a number of toxins including carbon monoxide, benzene, toluene, and xylene. New mineral occurrences discovered in association with Pennsylvania’s coal fires include hydrobasaluminite and voltaite in the assemblage alunogen, voltaite, and hydrobasaluminite discovered at an active gas vent near one of two currently active fire fronts in Centralia.

ABSTRACT Fallingwater is a UNESCO World Heritage Site that showcases a unique organic architectural design by Frank Lloyd Wright. Rising from bedrock in Mill Run, Pennsylvania, USA, Fallingwater incorporates large boulders into interior living spaces and is oriented with the geometry of a landscape created by the interplay of mountain and climate. Built to showcase local sandstone, Fallingwater is of the terrain. Building stone was quarried near the house from a 2-m-thick zone of quartzose medium to thin-bedded, fine- to very fine-grained sandstones in the Pennsylvanian upper Pottsville Formation. The building stone has abundant trace fossils and ripple marks, and is interpreted to have been deposited in shoreface environments with some tidal influence, or possibly in tidal flat environments. The house rests on sandstone bedrock of the Homewood sandstone, a Middle Pennsylvanian unit within the upper Pottsville Formation. At Fallingwater, the Homewood sandstone is interpreted to fill an incised valley with coarse, fluvial sandstones common in the lower part of the valley fill and finer-grained fluvial sandstones with possible evidence of marine or brackish influence in the upper fill. The Fallingwater building stone unit overlies the Homewood sandstone, above an interpreted marine flooding surface. Thickening of the Homewood sandstone in synclines suggests that deposition was influenced by Alleghanian deformation. Natural fractures in competent bedrock controlled the orientation of Bear Run at Fallingwater, and the fit of the house within the three-dimensional landscape of the valley, stream, and waterfall. Variation in natural fractures in bedded versus massive sandstone layers appears to have controlled the azimuths of the edges of the waterfalls at Fallingwater. Creation of the Fallingwater sandstone member of the Pottsville Formation is proposed.

Studies of the physical stratigraphy and analyses of the Middle Pennsylvanian flora and fauna of some coal beds and marine units of the Breathitt Formation in Kentucky, the Pottsville and Allegheny Formations in Ohio, and the Kanawha Formation and Charleston Sandstone in West Virginia show a need for the revision of stratigraphic nomenclature of the Pottsville Formation and the lower part of the Allegheny Formation and equivalent strata. Attempts to project single stratigraphic elements from one region to another have resulted historically in multiple miscorrelations. A major marine unit (previously misidentifled as the Vanport limestone of the Breathitt and Allegheny Formations) is here named the Obryan Member of the Breathitt Formation in northeastern Kentucky and of the Allegheny Formation in southern Ohio. The Obryan is characterized by the fusulinid Beedeina ashlandensis Douglass and is correlated with the Columbiana Member of the Allegheny Formation in central Ohio, which also contains that fusulinid. This correlation and the correlation of the Boggs Limestone Member of the Pottsville Formation in Ohio with the Stoney Fork Member of the Breathitt Formation in Kentucky are supported by analyses of Middle Pennsylvanian conodonts. A preliminary zonation of conodonts for strata of the Pottsville and Allegheny Formations shows that the major marine units of these formations in Ohio are biostratigraphically distinct. The Obryan Member is locally absent, but its position is marked by overlying clay beds in many parts of Kentucky, Ohio, and West Virginia. The Vanport Limestone Member of the Allegheny Formation (as identified in Pennsylvania and central Ohio) is here correlated with the Zaleski Flint Member (Allegheny Formation) in southern Ohio. The Kilgore Flint Member (new name, Breathitt Formation), the informal Limekiln limestone and informal Flint Ridge flint (Breathitt Formation) in Kentucky, and the informal Kanawha black flint (Kanawha Formation) in West Virginia are correlated with the Putnam Hill Limestone Member (Allegheny Formation) in Ohio. These latter chert deposits are shoreward (southward and southeastward) facies of a marine unit deposited mostly in restricted estuaries and bays. The chert deposits appear to result from a widespread episode of silicification of fossiliferous marine siltstones and limestones that locally affected underlying peats and silts. The Kilgore and Obryan Members and their equivalents are used as the two principal stratigraphic marker beds for analyses of Middle Pennsylvanian sections extending across northeastern Kentucky from central Ohio to central West Virginia. Clay units and coal beds that overlie the Obryan Member contain flint clay beds (tonsteins) that are, in part, the product of volcanic ash falls. The range zones of selected palynomorphs from northeastern Kentucky and southeastern Ohio corroborate some of the correlations proposed herein.

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.