Tonoloway Limestone Research Articles

SEDIMENTOLOGY AND CARBON ISOTOPE (δ13C) STRATIGRAPHY OF SILURIAN–DEVONIAN BOUNDARY INTERVAL STRATA, APPALACHIAN BASIN (PENNSYLVANIA, USA)

ABSTRACTSilurian–Devonian boundary interval strata deposited during the expansion of land plants record a major perturbation of the carbon cycle, the global Klonk Event, one of the largest carbon isotope excursions during the Phanerozoic. In the Appalachian Basin, these marine strata record the regional buildup to the Acadian Orogeny. This study reports new sedimentologic, paleontologic, ichnologic, and carbon isotope data from an exceptional quarry exposure in central Pennsylvania, USA, a historically understudied area between better-documented outcrops >500 km away to the southwest (West Virginia, Virginia, Maryland) and northeast (New York). Facies spanning the continuous 113-m thick outcrop are dominantly carbonate and fine-grained siliciclastic strata interpreted as being deposited in supratidal through subtidal environments, including oxygen-limited environments below storm wave base. They record parts of three transgressive-regressive cycles, in the (1) upper Silurian Tonoloway Formation, (2) upper Silurian–Lower Devonian Keyser Formation through lower Mandata Member of the Old Port Formation, and (3) Lower Devonian Mandata through Ridgeley Members of the Old Port Formation. Micrite matrix δ13Ccarb analyses exhibit a large, positive δ13Ccarb excursion (>5‰ amplitude). Outcrops of this interval in the Appalachian Basin occur in two belts, between which correlation has been historically challenging. The regional correlation presented herein is based on carbon-isotope trends and is more consistent with published conodont biostratigraphy and volcanic ash ages, an improvement over published correlations based on lithostratigraphy. Transgressive-regressive trends at the central Pennsylvania study site are not consistent with regional trends, indicating that local controls (tectonics, sediment supply) rather than global (eustasy) dominated depositional patterns in the Silurian–Devonian boundary interval in the Appalachian Basin.

Revision of the ostracod genus Velibeyrichia Henningsmoen, 1954 from the Silurian and Lower Devonian of North America

Camilleri, T.A., Warne, M.T., Holloway, D.J. & Weldon, E.A., 10 May 2019. Revision of the ostracod genus Velibeyrichia Henningsmoen, 1954 from the Silurian and Lower Devonian of North America. Alcheringa XXX, X–X. ISSN 0311-5518.Known occurrences of the ostracod genus Velibeyrichia are restricted to a number of Silurian to Lower Devonian geological strata in North America: the McKenzie Member of the Mifflintown Formation of Maryland and West Virginia; the Tonoloway Limestone of Maryland, West Virginia, Virginia and Pennsylvania; the Bloomsburg Formation of Maryland, Virginia and Pennsylvania; the Manlius Limestone of New York; and the Decker Limestone of New Jersey and New York. The genus includes six species: V. moodeyi (type species), V. mesleri, V. paucigranulosa, V. reticulosaccula, V. tonolowayensis and V. tricornia. The diagnostic combination of characters for this genus are: distinct deflection of the velum where it crosses the crumina in heteromorphs (adult female specimens), dorsal nodes on lobes L1 and L3, sexual dimorphism of the velum, and in tecnomorph specimens, either a shallow sulcus on lobe L3 or a zygal ridge (in adult tecnomorph specimens) extending from lobe L2 to lobe L3. The presence of one or the other of the latter two characters defines two distinct species groups.Tamara T.A. Camilleri* [tamara.camilleri@deakin.edu.au], Mark T. Warne* [mark.warne@deakin.edu.au] and Elizabeth A. Weldon [l.weldon@deakin.edu.au], Deakin University, Geelong, School of Life and Environmental Sciences & Centre for Integrative Ecology (Melbourne Campus), 221 Burwood Highway, Burwood, Victoria 3125, Australia; David J. Holloway [dhollow@museum.vic.gov.au], Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia. *Also affiliated with: Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia.

New trace fossil evidence for eurypterid swimming behaviour

AbstractWe describe a recently discovered trace fossil from a eurypterid Konservat‐Lagerstätte in the upper Silurian Tonoloway Formation of Pennsylvania, and formally describe contemporaneous traces from the Williamsville Formation Lagerstätte of Ontario. The traces from both localities are assigned here to Arcuites bertiensis igen. et isp. nov. Based on comparisons with previously described eurypterid trackways, neoichnological experiments, and the co‐occurrence with eurypterid remains, Arcuites is interpreted as having been made by the swimming leg (sixth prosomal appendage) of swimming juvenile to adult eurypteroid eurypterids, and represents the first unambiguous trace fossil evidence for eurypterid swimming behaviour. The morphology of Arcuites indicates that eurypteroid eurypterids swam using drag‐based rowing, whereby the animal propelled itself forward by moving its oar blade‐like swimming paddles in an in‐phase backstroke. Arcuites morphology also indicates that the eurypteroid swimming appendage had a greater degree of movement than was previously suggested, and a revised rowing model is proposed. Differences in the abundance of A. bertiensis in the Tonoloway and Williamsville formations suggest a bathymetric control on eurypterid swimming behaviour and trace production. The association of Arcuites with eurypterid body fossils in both units indicates that these Lagerstätten were autochthonous assemblages and provides additional evidence for eurypterid inhabitation of shallow subtidal marine environments in the late Silurian.

A NEW EURYPTERID LAGERSTATTE FROM THE UPPER SILURIAN OF PENNSYLVANIA

Eurypterids are generally rare in the fossil record, but occasionally occur in abundance. The genus Eurypterus , in particular, is well known from certain upper Silurian Lagerstatten of the northern Appalachian basin (New York and Ontario), but occurs far less frequently in the central and southern Appalachian basin (Pennsylvania, Maryland, and West Virginia, respectively). The recent discovery of an exceptionally preserved mass assemblage of Eurypterus in the upper Tonoloway Formation (upper Ludlow–Přidoli) of Pennsylvania provides new information on the behavior and life habitat of the genus in this region. Eurypterids at this locality are found in thinly laminated, calcareous shale deposited within the lower intertidal to shallow subtidal zone of a coastal mudflat or sabkha. Rare associated fauna of limited diversity, and evaporitic and desiccation features in associated beds, suggest a stressed environment with variable salinity and possible hypoxic conditions. Most eurypterids are disarticulated and fragmentary, but several fully articulated, exceptionally preserved specimens are present. Exoskeletal features and taphonomic indices values indicate a molt rather than death assemblage, and the presence of arthropod trackways suggests that Eurypterus sp. may have molted en masse in the vicinity of the burial site. Sequence stratigraphic interpretation of the site suggests that preservation of eurypterid remains is the result of occupation of ephemeral environmental (salinity/oxygen) conditions during a transgression. The occurrence of this new Lagerstatte within the upper Silurian succession of the central Appalachians, an interval which had heretofore yielded only rare, fragmentary remains, indicates that eurypterids were more prevalent in this region than previously thought.

Remagnetization of the Tonoloway Formation and the Helderberg Group in the Central Appalachians: testing the origin of syntilting magnetizations

SUMMARY Palaeomagnetic, rock magnetic, geochemical and strain studies of the Helderberg Group and the Tonoloway Formation in the Valley and Ridge province of West Virginia were performed to test the origin of syntilting magnetizations and to test the mechanisms of chemical remanent magnetization (CRM) acquisition. The test for a connection between strain and remagnetization was performed by comparing the types and levels of strain with the magnetic properties between the generally coarse-grained, thickly bedded Helderberg and the thinly bedded and finer-grained Tonoloway. Standard tilt tests as well as optimal differential untilting from two transects on the Wills Mountain anticline indicate that the Helderberg contains a pervasive late syntilting (∼30 per cent untilting) characteristic remanent magnetization (ChRM) whereas the Tonoloway contains a well defined early syntilting ChRM-1 (∼76 per cent untilting) as well as a ChRM-2, which is similar to the ChRM in the Helderberg. The ChRMs reside in magnetite. The rock magnetic results from the two units are similar although the Helderberg samples have a finer apparent grain size, perhaps as a result of magnetic hardening. Strain data reveal an apparent correlation between the syntilting magnetizations and types/degrees of pressure solution strain. Pressure solution strain is higher in the Helderberg and lower in the Tonoloway. Strain may have caused rotation of magnetic minerals, but it not clear that the differences in strain between the units were high enough to cause the rotations that are needed to explain the tilt test results. Several other viable hypotheses were also investigated. One hypothesis is a strain-enhanced chemical process that caused dissolution and precipitation of new magnetite in solution structures during folding. A preliminary test of this hypothesis produced inconclusive results. Another hypothesis, consistent with some of the characteristics of the magnetizations in the Helderberg and Tonoloway units, is that the rocks were partially to completely remagnetized by a piezoremanent remagnetization process. Geochemical results show that origin of the remanence carrying grains cannot be attributed to orogenic type fluids but were probably caused by a burial diagenetic process.

Synfolding remagnetization and deformation: results from Palaeozoic sedimentary rocks in West Virginia

SUMMARY Palaeomagnetic analysis was conducted at 27 sites from two stratigraphically adjacent Palaeozoic units along two transects (Meldey and Rig) of the Patterson Creek anticline in the Appalachian orogen of West Virginia to better understand the relationship between deformation and remagnetization. While no primary directions were observed, we isolated identical, well-defined, secondary Late Palaeozoic magnetizations in carbonates from the Late Silurian Tonoloway Formation and the Early Devonian Helderberg Group. Standard application of conventional palaeomagnetic fold tests suggests that the magnetizations are synfolding in the Helderberg Group and pre-folding to early synfolding in the Tonoloway Formation. A fold test on all data combined indicates a synfolding magnetization (best grouping at 60–65 per cent unfolding), but the resulting distributions are not circular. An alternative interpretation, based on optimal differential unfolding at the site mean level yields one group with a nearly pre-folding, or early synfolding, magnetization (>70 per cent unfolding) that is both circular and concordant with North America's apparent polar wander path. The second group has a ‘variable synfolding’ magnetization that is elliptical at the optimum unfolding level and falls off the path. Differences in either the age of remagnetization or viscous partial thermoremanent magnetization contamination cannot account for this result. The sites falling into the pre-folding group are biased towards the Tonoloway Formation, the Medley Transect, the northwest limb, away from small folds and lower dip angle relative to the sites in the synfolding group. The two groups defined by the fold test results also have a relationship with both total strain and strain partitioning. The rocks containing the early synfolding remanence exhibit less total strain and, in particular, less pressure solution strain relative to grain boundary sliding and calcite twinning. It is likely that the remagnetization in the entire area was coincident and occurred prior to folding even though some sites reveal synfolding directions. The variation in the behaviour of the remagnetization relative to folding is unclear at present but it indicates that pressure solution and stylolite formation are important processes in remagnetization. In any event, the relationship between deformation and magnetization is not simple. Apparently identical magnetizations from adjacent sites may have very different histories and/or responses to deformation. While the exact relationship between remagnetization and deformation remains elusive this study demonstrates that significant variation in behaviour can exist at a very local scale.

Rocky Gap Sandstone and Huntersville Formation--Potential Hydrocarbon Reservoirs of Southwestern Virginia: ABSTRACT

In southwestern Virginia, west of New River and east of East Stone Gap, the Lower Devonian Rocky Gap Sandstone and Huntersville Formation have the best potential as hydrocarbon reservoirs. Both units have a large areal extent and a combined thickness locally exceeding 150 ft (45 m). In outcrops formed by the present erosional cycle, the Rocky Gap Sandstone is a poorly indurated and friable sandstone. Secondary porosity could have formed also by leaching during erosional cycles both before and after deposition of the Oriskany Sandstone. Combined with primary and fracture porosity, the Rocky Gap Sandstone appears to have good reservoir potential. All of the exposures of the Huntersville Chert are fractured. The thrust faulting of southwestern Virginia could have led to the development of significant fracture permeability and porosity in the subsurface. Like the Huntersville Chert in West Virginia, the unit could become an important gas producer in southwestern Virginia. Both the Tonoloway Limestone and the Millboro Shale are excellent source beds for hydrocarbons. In western counties, the Onondaga Limestone also smells highly petroliferous after fracturing. Conodont color alteration index (CAI) maps of Silurian through Middle Devonian rocks in the Appalachian basin indicate that the rocks are above the upper limit of thermal maturity for gas. Unconformities throughout the area have the potential for stratigraphic traps. More detailed seismic surveys of the area can help to define structural and stratigraphic traps that are capped by the Millboro-Chattanooga Shale. End_of_Article - Last_Page 1928------------

Systematics and Paleoecology of Silicified Gastropoda of Tonoloway Formation (Upper Silurian) at Pinto, Maryland: ABSTRACT

The silicified gastropod fauna from the excellent Tonoloway reference section at Pinto in western Maryland has been studied by means of specimens obtained by etching bulk samples in hydrochloric acid. Of the four published gastropod taxa from this locality, three are placed in synonymy and one, based on an indeterminate internal mold, is restricted to its type. In addition to the aforementioned taxa, a new genus and species of Bellerophontacea in the subfamily Carinaropsinae and two species of Holopeid gastropods were recovered and described. Sedimentary and petrographic data suggest a low-intertidal to shallow-subtidal, soft-bottom, carbonate substrate environment for the gastropod-bearing beds sampled. This interpretation is supported by data from several studies of the paleoecology of Paleozoic gastropods which are systematically related and morphologically similar to the taxa recovered in this study. End_of_Article - Last_Page 440------------

Rank exposure index on a Silurian carbonate tidal flat

ABSTRACTAdequate discrimination between ancient intertidal and supratidal limestones and dolomites is often difficult because of vagueness of terms, problems of resolution, and the fact that most ‘diagnostic’sedimentary features are not restricted to narrow environmental zones. Furthermore, the rise and fall of sea‐level in restricted, epeiric seas is usually due more to storm surges than to true tides, and hence the occurrence and extent of tidal‐flat inundations are quite irregular. ‘Rank exposure index’is a concept introduced (1) to quantify the relative percentage of time that sediments are subaerially exposed and (2) to produce a more refined subdivision of shoreline carbonate rocks. The scheme employed to determine this index is a combination of numerical methods: cluster analysis separates 46 Tonoloway Limestone samples (Silurian of Maryland) into groups based on 16 sedimentary, mineralogic, and organic features, and minimum spanning tree produces a connected series of the five resultant groups. These groups are then ranked in sequence from 1 (greatest subaerial exposure) to 5 (least). Rocks of rank 1 are thought to have been deposited at the highest position within the tidal zone, as on a beach ridge. Rocks of decreasing rank reflect greater frequency of flooding. Those of rank 5 represent sediments deposited closest to low‐water level, as in a tidal pond. Rock type, mineralogy, fossil content, algal stromatolites, and sedimentary structures are closely related to exposure rank as interpreted for the Tonoloway carbonates. Rank exposure index, therefore, is a semi‐quantitative measure to aid in the detailed reconstruction of ancient shoreline environments.

On minimum spanning trees and the intergradation of clusters

Cluster analysis groups samples, but does not generally show gradations between clusters. To illustrate these relationships, principal-coordinate analysis and multidimensional scaling can be employed, but these methods may not be appropriate due to structural distortion. A minimum spanning tree (MST) computes a point-to-point path through the original matrix, and clusters are mapped on the MST diagram. The MST linkages, therefore, provide a natural continuum between the clusters, without distortion. Forty-six Silurian Tonoloway Limestone samples were analyzed for 16 sedimentary features indicative of subaerial exposure. Cluster analysis identified nine clusters which were reduced to five final, ordered groups by MST.

A Scheme for Multivariate Analysis in Carbonate Petrology with an Example from the Silurian Tonoloway Limestone

ABSTRACT Two methods of exploratory data analysis--a numerical classification system applied in conjunction with an ordination technique--were used to facilitate environmental interpretation of 61 Tonoloway Limestone samples from Pinto, Maryland. We suggest that the scheme of multivariate analysis presented here, because it involves nonparametric methods, is more applicable to typical geologic data than other strategies. In the Tonoloway Limestone 7 facies (clusters) were identified by Q-mode cluster analysis: (1) micrite, (2) micrite-dolomite, and (3) dolomite microfacies from the supratidal zone; (4) a micrite-peloid microfacies of the intertidal mud flat; (5) intraclast and (6) ooid-calcite cement microfacies representing a shallow-subtidal environment; and (7) a peloid-calcite cement micro acies from the deeper-subtidal environment. Multidimensional scaling illustrated interrelationships among the clusters and the gradational nature of samples; neither factor was observed by cluster analysis alone. Recognition of the gradational nature of samples then led to interpretations of three environmental gradients that were normal to the paleoshoreline. Hydrodynamic energy was low on both the tidal flat and offshore near wave base and systematically increased from both directions toward the shallow-subtidal environment. Petrographic fossil diversity was highest near wave base with a second, lesser peak on the intertidal mud flat; this variable decreased into the shallow-subtidal high-energy belt and also onto the supratidal mud flat. Dolomitization, apparently of two modes, was mo t pronounced in rocks of the schizohaline supratidal zone.

Silurian-Devonian Embayment into Appalachia: ABSTRACT

Several Silurian and Devonian formations, traced along central Appalachian outcrop belts, undergo anomalous changes in lithology, thickness, and faunal content in the area of Pendleton County, West Virginia. Hematitic sandstones are replaced by nonred sandstones, other sandstones change to shales, shale formations thin and pinch out, and Catskill red beds are replaced by nonred clastics. These changes represent a move from nearshore to more offshore deposition within an embayment along the western shoreline of Appalachia. The principal Silurian sandstones, the Tuscarora, Keefer, and Williamsport, all undergo facies changes in this area, becoming finer grained, argillaceous, and/or calcareous. Hematitic nearshore sandstones of the Rose Hill are replaced by nonred sandstones in the embayment. The Rochester and Rose Hill shales are thickest in, and largely confined to, the embayment; younger shales, the Big Mountain and Mandata, are replaced by sandstones south of the embayment. McKenzie shales contain more interbedded limestones in the embayment, and the fossiliferous middle Tonoloway Limestone contains a different fauna there than in adjacent areas. During Middle Devonian time, thicker, deeper water Needmore Shale beds in the area were flanked by shallower water facies of the Onesquethaw. The Mahantango Formation also is thickest in this area and thins abruptly to the south. Throughout this time two provenances supplied detritus, one east of West Virginia's eastern panhandle and the second in central Virginia. The Pendleton embayment was situated between these two regions that occasionally prograded westward, accentuating the embayment. For the final Devonian regression these areas are End_Page 846------------------------------ referred to as the Fulton and Augusta lobes of the Catskill delta, separated by Grant bay. End_of_Article - Last_Page 847------------

Scheme for Multivariate Analysis in Carbonate Petrology with Example from Silurian Tonoloway Limestone: ABSTRACT

Scheme for Multivariate Analysis in Carbonate Petrology with Example from Silurian Tonoloway Limestone: ABSTRACT

Flow of Weak Rocks in Appalachian Plateau Folds

A thin-skinned fold model of Appalachian Plateau folds in which layers do not thin in synclines is not possible geometrically. However, a two-layer model consisting of a gently folded competent layer overlying a deformed zone in which material flows from the synclines to the anticlines is both reasonable geometrically and supported by geologic evidence from the Plateau province of Pennsylvania and south-central New York. The deformed zone is composed of weak rocks--evaporites and shale--which have been deformed much more than the competent rocks above; the decollement marks the lower boundary of this deformed zone. Care should be taken in reconstructing the depocenters of rocks composing the deformed zone, because the original thicknesses have been altered by later deform tion. The Appalachian Plateau of Pennsylvania and New York may be divided into two regions on the basis of fold mechanics. In the northwestern and far western Plateau of Pennsylvania and south-central New York, Region I, the salt-bearing part of the Silurian Salina Group is the deformed zone; no other part of the stratigraphic section has flowed significantly. Synclines are broader than anticlines in the higher relief folds of Region I because much material has been removed from beneath the synclines and flanks to fill anticlines. In southwestern and central Pennsylvania, Region II, the anhydrite-rich Tonoloway formation and/or the Upper Ordovician Reedsville Shale flowed as well as salt. Complex thrust faulting and disharmonic folding at the level of the Oriskany Sandstone contribute significantly to the structural relief, but it cannot provide the major part of the relief. Balancing the shortening present at the Oriskany level requires either stretching at this level in the synclines or significant layer-parallel shortening at shallower stratigraphic levels.

Relation Between Tonoloway Limestone Environments of Deposition and Distribution of Salina Evaporites in West Virginia: ABSTRACT

Relation Between Tonoloway Limestone Environments of Deposition and Distribution of Salina Evaporites in West Virginia: ABSTRACT

Late Ordovician and Silurian Facies, Conditions of Deposition and Paleogeography in North-Central Appalachians: ABSTRACT

The Late Ordovician and Silurian sediments of the north-central Appalachians consist dominantly of detritals, their maximum thickness about one mile, swept from land surfaces on the east into a broad geosynclinal area. Three great detrital complexes reflect diastrophic-paleogeographic activities; they are formed by Bald Eagle-Oswego-Juniata-Queenston sediments; the Shawangunk-Tuscarora-Medina-Clinton-McKenzie sediments; the Bloomsburg-Vernon-Wills Creek-Camillus sediments. Carbonates are significant in the McKenzie limestone and shale and Lockport dolomite above the Clinton shales, and at higher levels are more widespread in the Tonoloway and Keyser limestones and their equivalents. Each of the three great detrital complexes attains its greatest thickness in Pennsylvania. The sedimentary maximum for the Bald Eagle-Oswego-Juniata-Queenston deposits is located in central Pennsylvania; maxima for the Shawangunk-Tuscarora-Medina-Clinton and Bloomsburg-Verona-Wills Creek-Camillus are shifted farther east. It is suggested that location of these maxima reflects the area of debouchment of an ancient major river system that drained from the Old-land Appalachian across the present region of northern New Jersey. The Late Ordovician Juniata-Bald Eagle sediments consist of poorly winnowed sand and silt detritals coarsening toward and north of Harrisburg to puddingstones with 3- to 6-inch pebbles of vein quartz, vitreous quartzites, meta-argillites, cherts. The Bald Eagle and Juniata are eastwardly equivalents of Maysville-Richmond marine shales and limestones of Ohio, but themselves lack fossils; they were deposited rapidly in freshened waters, perhaps in part directly on alluvial surfaces, in part in extensive lagoonal-estuarine regions. The Middle Silurian Clinton and McKenzie sediments contain profuse marine faunas; sedimentation as compared to evolution was long enough continued, and there are finely developed evolutionary faunal zones as well as intriguing facies problems. The Tuscarora sa dstone below the Clinton, and the Shawangunk conglomerate that replaces both Tuscarora and Clinton on the east, contain some eurypterids, and were deposited in part in shallow freshened seas where winnowing of quartz sands was active and effective, in part on the east on or near alluvial areas where gravelly, somewhat graywackyish sands are present. The Bloomsburg redbeds are nonfossiliferous. On the whole they are presumed to be alluvial; but extensive fine-grained sandstone members in the thinned western parts indicate active spreading in shallow bodies of water. The Bloomsburg red sediments grade westward into upper McKenzie and Wills Creek clayey deposits, and into lower beds of the Tonoloway limestone. Widespread Upper Silurian salt deposits are equivalent in age to parts of the Blo msburg redbeds, but not co-extensive with them. In the Late Silurian, marine advances culminated in sedimentation of the Tonoloway and Keyser limestones. The Keyser seaways had good oceanic connections both north and south, and in them flourished extensive and diagnostic, progressively changing assemblages of brachiopods, corals, bryozoans, and ostracods, that are excellent for correlation. Waters well connected with the oceans and favorable for profuse marine life, persisted along much of the Appalachian region during Lower Devonian Helderbergian and Oriskany sedimentation; at times these waters were clear over large areas; elsewhere and at other times well winnowed sands and clays accumulated slowly over the sea floor. In their northwesterly subsurface extensions, gas has been extensively produced from the Lower Silurian Tuscarora-White Medina and Lower Devonian Oriskany sands: some production has come from Middle Silurian Lockport equivalents of the McKenzie formation; the Late Ordovician Bald Eagle-Oswego sands may have reservoir possibilities. End_of_Article - Last_Page 2160------------

Early Devonian and late Silurian formations of southeastern Pennsylvania

Research Article| August 01, 1941 Early Devonian and late Silurian formations of southeastern Pennsylvania CHARLES K. SWARTZ; CHARLES K. SWARTZ Search for other works by this author on: GSW Google Scholar FRANK M. SWARTZ FRANK M. SWARTZ Search for other works by this author on: GSW Google Scholar GSA Bulletin (1941) 52 (8): 1129–1192. https://doi.org/10.1130/GSAB-52-1129 Article history received: 12 Nov 1940 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation CHARLES K. SWARTZ, FRANK M. SWARTZ; Early Devonian and late Silurian formations of southeastern Pennsylvania. GSA Bulletin 1941;; 52 (8): 1129–1192. doi: https://doi.org/10.1130/GSAB-52-1129 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The area studied is part of a separate Silurian province which extends south of the coal measures from the Schuylkill River to southeastern New York. It is divided into two parts, southern and northern, each characterized by distinctive faunas and lithology.Numerous sections are studied embracing beds from the Silurian Bloomsburg to the base of the Middle Devonian Onondaga; their formations are described, faunas given, and beds correlated.The Middle Devonian Palmerton sandstone and Bowmanstown chert of the southern area, long designated Oriskany, are correlated with the Esopus shale of the northern area. The underlying Oriskany sandstone is present in different facies in the southern and northern areas.The Helderberg and Keyser groups differ in facies in the two areas. They are briefly described and correlated.The Silurian Poxono Island shale and Bossardville limestone are present in both areas. They are similar to, and homotaxial with, the Wills Creek shale and Tonolo-way limestone, respectively, of central Pennsylvania and Maryland but lie in a different province, and the corresponding formations differ in their time limits. Both are believed to be later than the Wills Creek shale.The formations above the Bloomsburg thin progressively and disappear southwest-ward, but the Bloomsburg is continuous throughout the area.The Keyser limestone presents both Silurian and Devonian aspects. It is tentatively made Silurian, but the determination of its true age must await further study of its relation to the European sequence. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.