Abstract An embankment on the new Ohio Turnpike, 35 feet high, started to fail on September 1, 1955, just a month prior to the date of opening of the highway. The toe of the north side of the embankment started to bulge, and cracks developed on the flanks and in the pavement. The situation was controlled by placing backfill on the toe and flank of the embankment, making the final slope 1 to 3, with an intermediate berm of 1 to 10. Grout was placed beneath the pavement to fill the voids caused by the slumping. Boreholes drilled through the embankment indicated that cause of failure was pore pressure and instability developed in lake beds underlying the embankment. Maximum pore pressures of 13 feet were observed, which in the ensuing months gradually declined.

Abstract Carbonate and interbedded siliciclastic-carbonate rocks of the Upper Cambrian Gatesburg Formation represent deposition on, and proximate to, the great American carbonate bank (GACB), a broad, rimmed platform of low relief that was subject to periodic sea level changes. This environmental setting produced a series of complex mixed carbonate and carbonate-siliciclastic sequences (dominated by carbonates) with limited lateral continuity between outcrops and wells. Many of the rocks formed on the GACB are targets of active petroleum exploration in western and north-central Pennsylvania, as well as in other areas of the Appalachian Basin. Potential reservoir targets include the Upper Cambrian Upper Sandy member of the Gatesburg Formation (Rose Run Sandstone of Kentucky and Ohio) and paleotopo-graphic highs and paleokarstin the Mines Member of the Gatesburg Formation below the Knox unconformity (considered to be part of the Beekmantown throughout much of the Appalachian Basin). Although the latter typically are seismic plays, with companies searching for both stratigraphic and structural traps, knowledge of the patterns of sedimentation on the GACB is also critical to exploration efforts. Mixtures of carbonate and siliciclastic rocks resulted from spatial and temporal variability in depositional systems across the GACB, creating acute and complex reservoir heterogeneities. The distribution of porous and permeable sandstone and carbonate facies within the Cambrian sequence, as well as the juxtaposition of sandstones and paleokarst beneath the Knox unconformity, undoubtedly influenced the migration of fluids, including brines that diagenetically altered many of the rocks, primarily through dolomiti-zation. The spatial distribution of reservoir seals, reservoir compartmentalization, and dia-genetically controlled pore geometry are partially or wholly sedimentologic features.

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.

Abstract This walking tour will consider local geology, touch on local history, and focus on the building stones used in downtown Dayton. Building stones and construction materials used along Main Street are the main interest. Special attention will be paid to “Dayton’s own,” the Dayton limestone—a stone considered by State Geologist Edward Orton in the second half of the nineteenth century ( Orton, 1870 , 1893 ) as one of Ohio’s finest building stones. The Dayton Formation (Dayton limestone) was used extensively as a building stone in the Dayton area (and farther afield) during the nineteenth and early years of the twentieth centuries during the growth of Dayton. Perhaps the zenith of the Dayton limestone building-stone industry is characterized by the Old Courthouse (1850), an important building in the Greek-Revival architectural-style that saw the use of Dayton limestone not only for the exterior of the building but also, unusually, and perhaps with a little too much enthusiasm, for slabs of limestone for the roof. This building has much local historical significance— both Presidents Abraham Lincoln and John F. Kennedy addressed the public from its steps. Dayton limestone was used for the commemorative stone from the State of Ohio, installed in 1850, inside the Washington Memorial, Washington, D.C., and for part of the “Ohio House” built for the International Exhibition at Fairmount Park, Philadelphia, Pennsylvania, commemorating the centennial of the signing of the Declaration of Independence in 1876. Use of the stone is also documented in Cincinnati, Columbus, and Chicago. Recent developments along East Monument Avenue and Patterson Boulevard— RiverScape and the Patterson Boulevard canal walk—as well as some of the buildings, will be discussed. The “Great Dayton Flood” of 1913 probably resulted in excess of four hundred deaths along the Great Miami River valley and its watershed. The Miami Conservancy District oversees the flood-prevention scheme that developed after the 1913 flood; their headquarters are housed in a building that overlooks the Great Miami River in downtown Dayton. Flood-prevention modifications to the Great Miami River can be seen adjacent to downtown.

Abstract During the Pleistocene, the Laurentian Ice Sheet extended southward into western Pennsylvania. This field trip identifies a number of periglacial features from the Pittsburgh Low Plateau section to the Allegheny Mountain section of the Appalachian Plateaus Province that formed near the Pleistocene ice sheet front. Evidence of Pleistocene periglacial climate in this area includes glacial lake deposits in the Monongahela River valley near Morgantown, West Virginia, and Sphagnum peat bogs, rock cities, and patterned ground in plateau areas surrounding the Upper Youghiogheny River basin in Garrett County, Maryland, and the Laurel Highlands of Somerset County, Pennsylvania. In the high lying basins of the Allegheny Mountains, Pleistocene peat bogs still harbor species characteristic of more northerly latitudes due to local frost pocket conditions.

ABSTRACT During the Pleistocene, the Laurentian Ice Sheet extended southward into northwestern Pennsylvania. This field trip identifies a number of periglacial features from the Appalachian Plateaus and Ridge and Valley provinces that formed near the Pleistocene ice sheet front. Evidence of Pleistocene periglacial climate in this area includes glacial lake deposits in the Monongahela River valley near Morgantown, West Virginia, and Sphagnum peatlands, rock cities, and patterned ground in plateau areas surrounding the Upper Youghiogheny River basin in Garrett County, Maryland, and the Laurel Highlands of Somerset County, Pennsylvania, USA. In the high-lying basins of the Allegheny Mountains, Pleistocene peatlands still harbor species characteristic of more northerly latitudes due to local frost pocket conditions. Pleistocene fauna preserved in a cave deposit in Allegany County, Maryland, record a diverse mammalian assemblage indicative of taiga forest habitat in the Ridge and Valley province.

Abstract The Allegheny Portage Railroad, just one leg of the Pennsylvania Mainline Canal system, was the first railroad over the Allegheny Mountains, an imposing physiographic barrier to westward migration in the early 1800s. Construction of the canal system began in 1826 and continued until ca. 1840 without interruption. The Allegheny Portage Railroad began construction in 1831 and opened for business in 1834. This astonishing engineering feat took less than four years for completion, despite the necessity of 10 inclined planes and the use of the new-fangled railroad locomotives. Construction made use of many of the natural resources occurring along and adjacent to the right-of-way, especially the Pennsylvanian-aged sandstones used for the “sleepers” that held the rails in place. Travel occurred in sectional canal boats, boats that were built in two or three pieces that could be easily loaded onto rail cars. Passengers and goods were loaded onto the boat sections in Philadelphia, which were then hauled by horse or locomotive to the Susquehanna River west of Lancaster. The boats traveled north on the Susquehanna River canal to the mouth of the Juniata River north of Harrisburg, then along the Juniata River canal to Hollidaysburg near the foot of Allegheny Mountain. There, the boats were taken from the water, loaded onto rail cars, and hauled over the mountain on the Allegheny Portage Railroad to Johnstown where they were unloaded into the Conemaugh River canal for the journey to Pittsburgh. A New Allegheny Portage Railroad was built in the 1850s to bypass the inclined planes. It was no sooner built, however, when the state sold the entire canal system to the Pennsylvania Railroad for less than half the cost of construction. The Pennsylvania Railroad promptly dismantled the Allegheny Portage Railroad and filled in the canals. Today, the Allegheny Portage Railroad National Historic Site oversees and administers the preservation of the few remaining aspects of the old railroad.