The Field Conference of Pennsylvania Geologists has in the past visited many sites along the Ordovician-Silurian boundary. The “transitional” contact between Silurian and Ordovician rocks in central Pennsylvania becomes unconformable in eastern Pennsylvania to southeastern New York as the hiatus widens. Following the northeastward decrease in intensity of deformation in the Ridge and Valley through New Jersey, this trip will begin with the high-angle contact between the Tuscarora and Hamburg sequence at the Schuylkill River and proceed for 120 miles along the very low-angle unconformable contact between Lehigh Gap, PA and Ellenville, NY. We will suggest predominant Alleghanian deformation along the contact and, in New Jersey and New York, propose zones of increasing southeastward Taconic deformation away from the contact. We will demonstrate the relative intensities and trends of Taconic and Alleghanian deformation in New York, and will comment on the northeastward dying-out of Alleghanian structures in the Shawangunk Mountains. The perplexing story of events during the Taconic hiatus, lasting perhaps 10-20 million years, will be illuminated by an unusual diamictite in southeastern New York.

The 2011 Field Conference of Pennsylvania Geologists focused on the Permian- Carboniferous age rocks of the Dunkard Basin in Southwestern Pennsylvania, the northern panhandle of West Virginia, and Eastern Ohio. We looked at the youngest Paleozoic strata of the Appalachians exposed along winding roads built on the steep valley walls of this remote region. We closely examined the various lithologic features and fossils, touched on dramatic north to south facies change in the basin, and considered the paleoenvironmental and paleoclimatic implications of all of this. We once again asked the question about the age of Dunkard strata – Pennsylvanian or Permian? Attention was also be given to the unique topographic features of the region – the narrow, sinuous ridge tops and deep valleys shaped by strong headward erosion of streams and extensive landslides.

The first day’s trip will be devoted to the early Paleozoic platform and slope deposits near the Susquehanna River. Stratigraphic units will include the Precambrian Accomac (Catoctin) Volcanics, Cambrian Hellam Conglomerate and Chickies Quartzite, the Cambrian transition from platform carbonates of the Ledger Dolomite into the Conestoga slope limestones and olistostromes, the Octoraro (Antietam ?) Schist, and some Beekmantown carbonates. Taconic and Alleghanian-age structures will illustrate several types of cleavage, the infamous Martic thrust zone, enigmatic folds and nappe emplacement mechanics, pirated cleavages at Chickies rock, and boudin mechanics and thick carbonate mylonitic zones produced by the exposed Alleghanian-age Chickies-Oregon Thrust in the Prospect Quarry. That evening the traditional banquet lecture will be given by Damian Nance on “The Rheic Ocean in relation to the Appalachian Orogenic belt.” The second day’s trip will focus on the Taconic foreland basin mostly in Dauphin and Lebanon Counties. Recent work by Ganis, Repetski and others has produced about 50 sites with high quality graptolite and/or condont dates. With these constraints, new mapping by Ganis and Blackmer has begun to make sense out of the Martinsburg flysch and its allochthons. These are now named as a separate formation, the sub-Martinsburg Dauphin Formation that has been thrust emplaced onto the carbonate platform and folded along with those carbonates and the overlying flysch into the Lebanon Valley nappe complex. These map relationships are at complete odds to traditional views of the Hamburg klippe as an erosionally isolated part of a late stage thrust sheet and suggest the “Hamburg klippe” term should be abandoned. The stops will demonstrate the stages of evolution of the Cocalico-Dauphin-Martinsburg foreland basin from the Myerstown Formation first disturbances of the platform carbonates, through emplacement from some distant deep sea source of the deep water Dauphin allochthons, to deposition of the overlying Martinsburg flysch and ultimately to gross overturning of it all as part of the Lebanon Valley nappe complex.

The 74th Annual Field Conference of Pennsylvania Geologists returned to northwestern Pennsylvania to celebrate the 150th anniversary of the founding of the modern petroleum industry by the successful completion of the Drake Well in Titusville on August 27, 1859. The first day of the field trip began by looking at an excellent outcrop of the uppermost Devonian Berea Sandstone and adjacent rocks in Oil City. From there we headed north along Oil Creek to relive the history of the early oil days. Stops included: the McClintock #1 well, the world’s oldest producing oil well; Petroleum Centre, the heart of the industry during the early days; an early attempt to mine to the oil reservoirs; Blood Farm, with much of its old oilfield equipment still extant; Pithole, the famous ghost town that provides a sobering look at the rise and fall of an area in the throes of “black gold fever;” and Drake Well Museum where it all started. At the Drake Well, conferees also had the opportunity to examine an outcrop of the Upper Devonian “Drake Well Formation” (informal name) and search for fossils. The morning of day two was spent at a very complete esker-delta-lacustrine plain complex in northern Butler County. The new lidar images clearly show the complex. The story includes a couple of drainage diversions caused by the delta resulting in a stream that flows across and up its valley. In addition to the geomorphic relationships of the complex, we also had an opportunity to visit an active sand and gravel pit in the delta, and see the type of sedimentation that occurs in that environment. The afternoon of the second day of the Field Conference was devoted to reexamining the long-studied and long-debated end-Devonian stratigraphic succession in northwest Pennsylvania. Advances in global geochronology, recognition of the importance of the Hangenberg mass-extinction event, plus recent discoveries of apparent end-Devonian glacial activity have raised the stakes for improving our knowledge of the stratigraphy and paleontology in this regional time-slice. The results of extensive fieldwork in Crawford County and surrounding areas, as well as a partial review of the extensive and complex history of stratigraphic investigations of area sections will be presented.

The 73rd Annual Field Conference of Pennsylvania offered a duel focus: the geology of the Mesozoic Gettysburg basin and the military geology of the battle of Gettysburg. In the history of the Field Conference only one STOP has examined Mesozoic rocks. An entire day was devoted to a geological transect across the Gettysburg basin. The Gettysburg basin is an erosional remnant of the early Mesozoic Birdsboro basin, formed on the roots of the Permian Alleghanian orogeny in the middle of Pangea near the edge of what was to become the Atlantic Ocean in the middle Jurassic. Approximately 7,000 m of mostly terrigenous sediment accumulated in an elongate trough (the Birdsboro basin) during the late Triassic and earliest Jurassic. We visited deposits of the various depositional environments, including the basal fanglomerate, the fluvial playa, the lacustrine and shoreline, and the upper fanglomerates. We also entered a quarry that exposes cycles in the Ordovician Beekmantown, and considered the tectonic implications for its presence within the Gettysburg basin. The second day of the Field Conference was spent entirely within the Gettysburg National Military Park. No famous land battle in all the annals of military history exemplifies the influence of topography and geology on the course and outcome of the engagement more than the battle of Gettysburg. From the Blue Ridge-South Mountain barrier that shielded the Confederate Army of Northern Virginia from the Union Army of the Potomac both during the movement to and retreat from Gettysburg to the spoke-like road network that led both armies to the fatal field to the rocky diabase fishhook upon which the Union forces anchored their final defensive position, the landscape dominated every phase of the Gettysburg campaign. We visited several of the well-known sites at Gettysburg National Military Park, including the railroad cuts west of town, the Lee Memorial on Seminary Ridge, Little Round Top, Devil’s Den, the Peach Orchard, and the High Water Mark on Cemetery Ridge-emphasizing at each STOP how topographic and geologic conditions affected military tactics and results.

The 72nd Annual Field Conference of Pennsylvania took place in the scenic and geologically fascinating area near Lewistown, located in the heart of Pennsylvania’s picturesque Ridge and Valley province. The trip emphasized the products of recent geological mapping in the area surrounding the beautiful Kishacoquillas Valley – a locus of Amish and Mennonite farming. Geologic emphasis was on the reinterpreted structural geology of the area, which highlights pre-Alleghenian thrust faults that demonstrably were later refolded during the development of the Appalachian Mountains. Ordovician, Silurian and Devonian stratigraphy of the area was also highlighted with its local variations. The first day included examining the spectacular newly created road cut at the east end of the Lewistown Narrows where the Tuscarora and Rose Hill Formations may be seen in two very different structural settings. The remainder of the day included stops in no less than three quarries, each with structural complexities, including one in semi-consolidated Ridgeley sandstone with fossils. Day one lunch was atop Jacks Mountain featuring panoramic views of both adjacent valleys and ridge top quartzite stratigraphy. The first three stops of the second day examined the structural relationships of the pre-Alleghenian thrusting in the Kishacoquillas Valley starting with a stop at Reedsville to view “Trenton-Black River” stratigraphy and thrust fault structure. Overturned Bald Eagle conglomerate was seen at a stop demonstrating additional structures in the footwall of a refolded thrust fault. Then to road outcrops in the Ridgeley sandstone with a cross-bedded crag and a giant sinkhole in the Tonoloway Formation. Two pre-Conference Trips included a trip to an enigmatic boulder field of Ridgely sandstone that has no apparent source, and an underground excursion through the Rupert Cave in the Old Port Formation.

The 71st Annual Field Conference of Pennsylvania took place amid some of the grandest scenery in the northeastern United States, counting among its attractions two of Pennsylvania’s most picturesque and geologically interesting state parks—Ricketts Glen and Worlds End. Ricketts Glen boasts 22 named waterfalls among its many attractions, and Worlds End has two spectacular scenic overlooks and (as far as we know) the biggest Pottsville “rock city” on the High Plateau. Emphasis was on the geomorphological development and glacial history of the region that encompasses North Mountain, Eagles Mere, and the uplands bordering Loyalsock Creek, but STOPS dealing with the stratigraphy and paleontology of the Lock Haven, Catskill, and Huntley Mountain Formations were also be included. Of particular stratigraphic and sedimentologic interest was a pre-Conference field trip to the enigmatic “Haystacks” in the upper part of the Huntley Mountain Formation on Loyalsock Creek. A second pre-conference field trip involved an all-day hike through the Glens and along the Highland Trail at Ricketts Glen State Park. A late addition to the “road log” will be discussions of the damage inflicted by the “no-name” flood of late June 2006.

The 2005 Field Conference visited glacial and bedrock sections in the Shenango and Beaver River valleys in northwestern Pennsylvania. The glacial sections included a complex section of glaciolacustrine sediments with a plethora of sedimentary structures at Cochranton. A lake bluff section on Pymatuning Reservoir at Pymatuning State Park addressed problems of glacial stratigraphy, history, sedimentology, and geomorphology. The Booth Run section exposed all 5 of White and others’ (1969) Titusville Till sheets, separated by sand and gravel beds, and displayed some complicated weathering patterns. The bedrock sections include two type sections (Mercer and Homewood) described by I.C. White in the late 1800s. These were compared to modern exposures of the lower Allegheny – upper Pottsville interval, and illustrated why some of the type sections are “stereotype” sections. Also included were a stop at the Vanport Limestone, and an unusual asymmetric fold with multiple thrust faults at New Castle.

For the first time in Field Conference history, we traveled to Delaware to examine the Wissahickon and the Wilmington Complex. A highlight of the Delaware excursion on Day 1 was a ride on the section of the historic Wilmington and Western Railroad that has been repaired since 2003’s pre-hurricane storm rained destruction on the Delaware Valley. We then got a taste of our neighbors’ hospitality with lunch at stop leader Peg Plank’s house where we will also visit her quarry in the “Mt. Cuba” Wissahickon. We headed back through horse country in Chester County, PA to visit a quarry in the Cockeysville Marble and a typical Piedmont roadside outcrop of “Doe Run” Wissahickon. On Day 2, we visited Delaware County, PA to further explore the relationship of the Wissahickon to the Wilmington Complex arc and (finally!) see some “type” Wissahickon. We also looked at the Wissahickon in contact with Grenvillian gneiss of the Avondale Massif. At least we thought it was Grenvillian until zircons from the contact zone in this railroad cut gave a Silurian age.

For the first time in its history, the 2003 Annual Field Conference of Pennsylvania Geologists visited the Altoona area in west-central PA. Here, the Ridge and Valley Physiographic Province meets the Appalachian Plateaus Province along the Allegheny Front. Stops on Day 1 focused on the Silurian-Devonian carbonates in the lowlands of the Ridge and Valley. We examined excellent exposures of these units and addressed their stratigraphy, sedimentology, and paleontology, as well as their economic potential. In contrast, stops throughout Day 2 addressed the challenges of the geology and the landscape to the region’s history, and blended the past and the present across the Allegheny Front. Highlights included: Fort Roberdeau, a reconstructed American Revolutionary stockade; a train excursion up the Front around the Horseshoe Curve and through Gallitzin’s Tunnel Hill (re-enacting the first Field Conference in 1931); the Allegheny Portage Railroad National Historic Site; and an active strip-mine operation.