North-central Appalachians Research Articles

Multi-objective planning for food production in a mountainous region: Strategic land utilization for meeting food demand and economic revitalization

• Multi-objective planning leads to increased food production in a mountainous region • Land grading criteria are used to conserve crop diversity with limited land • Land accessibility analysis suggests potential for expandable crop production • Surplus horticultural production showed immense economic revitalization potential The mountainous landscapes and significant decline of predominate industries have made the North Central Appalachian (NCA) region vulnerable to economic shocks. Given the rugged terrain that hinders large-scale industrialization, community-supported food production can be a sustainable solution to help meet food demand and revitalize regional economy. This study evaluated the potential of strategic utilization of arable land in a mountainous region to increase niche crops production and revenue. Using West Virginia as a study area, current food production shortages were estimated to be -47% to -100% for all 30 crops. A novel multi-objective planning function that considers land slope, crop diversity, yield and sale price was developed and applied to reallocate existing and expandable arable lands for increased food production. Accessibility, a numeric measure determined by the land slope and traversable road networks, was used to delineate availability of arable lands, and the accessibility values (0.816-0.999) of the expandable arable land suggests high accessibility. Results showed that demand for horticultural crops can be extensively met (potential/demand = ∼39) by restructuring the cropland; whereas field crop gaps can be slightly ( i.e ., 0.6%) reduced with the addition of expandable land. The analyses yielded a surplus production of horticultural foods while increasing crop diversity, and showed immense potential for economic revitalization. The methodology developed in this study and the results could be used to leverage regional policymaking to significantly reduce food shortage and to enhance economic revival in the NCA and similar regions.

Soil and geomorphic patterns within relict charcoal hearths could represent unique ecosystem niches

Hearths used for 19th and 20th century charcoal manufacturing have been found to have unique plant communities or to produce unique growth characteristics for some species but not others. Given known differences in hearth morphology, within hearth physical and chemical differences may exist and result in unique ecologic niches. We examined soil stratigraphy across 8 relict charcoal hearths (RCH) and control soils on different landforms near a 19th century furnace complex (Greenwood Furnace, northcentral Appalachians USA). Soils were analyzed for particle size, total and trace elements, and fertility. Platform creation resulted in soils from upslope RCH positions mixed with subsurface materials on the downslope side to create a stabilized platform. The thin, uniform thickness of charcoal surface horizons (Ac) indicate that RCHs were not used more than once for charcoal manufacturing or that charcoal was always removed very efficiently. While rubification of soil or rock from high heat was seen in 6 of 8 sites sampled, it was not extensive across sampled areas of any one hearth, which indicate hearth use may not be frequent, hot enough, or spatially disparate. Soil fertility characteristics change within RCHs but also by landscape position. Downslope RCH positions are enriched in some parameters compared to control soils (total C, Mehlich 3 Mg, Ca, and Aquia Regia digestion Mn) and that enrichment often is from the surface downward. Downslope enrichment within RCH soils may have occurred from charcoal and released ions, slope erosion and accumulation, or transportation of constructed materials during RCH creation. Landscape position may accentuate or mute soil chemistry differences. Greenwood Furnace RCHs have unique patterns of chemistry, which could result in unique niches for flora and maybe fauna within RCH. Future research could more closely investigate whether hearths support unique species assemblages and how they may play a role in enhancing today's forest biodiversity.

Species and physiographic factors drive Indian cucumber root and Canada mayflower plant chemistry: Implications for white-tailed deer forage quality

Nutrition is fundamental to white-tailed deer (Odocoileus virginianus) management given its relationship to habitat carrying capacity and population productivity. Ecological Sites (ESs) are a United States federal landscape management unit of specific land potential due to unique soils, topography, climate, parent material, and perhaps deer forage nutritional value. We present results of a study that extends the use of ESs to inform white-tailed deer management by evaluating indicator plant chemistry in two spring forb species, Indian cucumber root (Medeola virginiana) and Canada mayflower (Maianthemum canadense), across the northcentral Appalachians. We sampled spring forbs and underlying soils across two ESs: Dry, upland, oak–maple–hemlock hardwood forest (OMH) and Deep soil, high slope, northern hardwood forests (NHF). Plant elemental content, soil pH, and site aspect, slope and elevation were measured. Our results show that forb chemistry differs between species and within a species geographically. Indian cucumber root, as compared to Canada mayflower, has significantly higher Mg, Na, Cu, Fe, and Zn, and lower Mn. Canada mayflower in the NHF ES, versus OMH ES, was found to have significantly higher K, Mn, and B. Indian cucumber root in the NHF ES, versus the OMH ES, was found to have significantly higher Mg, Al, Fe, and Ca:P ratio but lower K. Linear discriminant analysis shows that plant tissue Mn was the best discriminator between species, and between ESs, Canada mayflower plant tissue Mn and Indian cucumber plant tissue P, K, Ca, Mg and Mn were best discriminators. Given that nutrition determines habitat carrying capacity, differences in forage nutrition between ESs may have different potentials to support deer. Forage nutrition is an important aspect of deer habitat conditions and carrying capacity, thus ESs are likely to support deer populations with different growth potential, which means that even if the same plant species occur in different ESs their nutritional value to deer may differ.

Small anthropogenic landforms from past charcoal production control moisture dynamics and chemistry in northcentral Appalachian soils

Throughout the northeastern United States (U.S.) and Europe, relict charcoal hearths (RCHs) are regularly being discovered in proximity to furnaces once used for the extraction of metal from ore or quick-lime production; charcoal produced in hearths was used as a furnace fuel. Given previous research has shown that topographic and subsurface disturbance can be great when a hearth is constructed, we hypothesize that hearth construction alters surface hydrology and soil chemistry in environments in and near hearths. We used a landscape classification process to identify 6758 hearths near furnaces at Greenwood and Pine Grove Furnace State Park, central and southcentral Pennsylvania, U.S. Two types of digital elevation model wetness indexes were used to quantify surface hydrology effects in and around hearths. Modeled wetness conditions were compared to field soil volumetric water content in RCHs near Greenwood Furnace State Park. Modeled wetness indexes indicate that RCH interiors are significantly wetter than RCH rim areas; RCHs are acting as a landscape moisture sink. Results also indicate that RCHs on slopes result in downslope drier conditions below RCHs. Field measured volumetric water content indicates that as distance from the center of the hearth increases, soil moisture significantly decreases. Geomorphic position was found to not be related to RCH wetness. Soil from RCHs, compared to nearby native soils, has significantly higher total C, a lower Mehlich 3 extractable acidity, higher Ca and P. No trend was evident with RCH soil chemistry and geomorphic position. The high frequency of RCH occurrence, in proximity to the furnace's RCHs supported, suggests that RCHs today could locally be an important niche for understory flora and fauna. Further research could explore how RCHs might be affecting surrounding plant populations and how within RCH patterns, especially on hillslopes, might represent a distinctly different scale of physical and chemical variability.

Distribution of silty mantles in soils of the Northcentral Appalachians, USA

Across the northcentral Appalachians, USA, high silt content soils are found as silty mantles or deep, high silt content pedons. The origin of such soils can be attributed to additions of wind-blown dust deposits (WBD) or local parent materials (i.e. shales or siltstone lithology). Previous research on silt soils originating specifically from WBD attributed to late marine isotope stage (MIS) 2 loess has often been isolated to drainageways receiving outwash from deglaciation. We hypothesize that thin (<25–50 cm) silty mantles, and some deep silt soils occurring farther from outwash systems, are also indicative of post MIS 2 WBD and their extent is widespread. To test this hypothesis, we evaluated over 900 pedons from an ~119,280 km2 area of the northcentral Appalachians, USA to: (i) develop a particle size signature indicative of soils largely derived from WBD versus local parent materials, (ii) determine the potential depth of WBD additions to soils, and (iii) document the spatial extent of WBD versus deep, high-silt content soils across part of the region. Results suggest that silty mantles are prevalent across the study area and have a particle size signature indicative of loess and the mean depth of WBD additions to soils is ~50 cm. Below 50 cm, local lithology or pedogenesis more influences particle size trends. Pedon results were applied in a spatial modeling effort using the USA Soil Survey Geographic Database (SSURGO) to document the extent of silty mantles (over non-silt sourced parent materials) and deep, high silt content soils. Model results indicate silty mantles are common on stable landscape positions or positions that accumulate sediments (depressions or valleys). Our finding of silty mantles, or deep high silt content profiles, over lithologies high in sand infers a source other than the underlying lithology. In addition, the presence of such silty mantles on summits and upper slopes suggests the importance of these landforms as stable positions preserving WBD. Our results suggest that stable landforms preserve WBD deposits and where topography is of lesser relief, broader deposition across several aspects is common. Aspect dependent deposition is tied to glaciofluvial sources of WBD, and modeled silty mantles correspond strongly to regional studies of loess.

Soil chemistry, and not short-term (1-2 year) deer exclusion, explains understory plant occupancy in forests affected by acid deposition.

The loss of species diversity and plant community structure throughout the temperate deciduous forests of North America have often been attributed to overbrowsing by white-tailed deer (Odocoileus virginanus). Slow species recovery following removal from browsing, or reduction in deer density, has been termed a legacy effect of past deer herbivory. However, vegetation legacy effects have also coincided with changes to soil chemistry throughout the north-eastern USA. In this paper, we assess the viability of soil chemistry (i.e. pH, extractable nutrients and extractable metals) and other factors (topography, light, overstory basal area and location) as alternative explanations for a lack of vegetation recovery. We compared the relative effects of soil chemistry, site conditions and short-term (1-2 year) deer exclusion on single-species occupancy probabilities of 10 plant taxa common to oak-hickory forests in central Pennsylvania. We found detection for all modelled species was constant and high ( > 0.65), and occupancy probability of most taxa was best explained by at least one soil chemistry parameter. Specifically, ericaceous competing vegetation was more likely to occupy acidic (pH < 3.5), base cation-poor (K < 0.20 cmolc kg-1) sites, while deer-preferred plants were less likely to occur when soil manganese exceeded 0.1 cmolc kg-1. Short-term deer exclusion did not explain occupancy of any plant taxon, and site conditions were of nominal importance. This study demonstrates the importance of soil chemistry in shaping plant community composition in the north-central Appalachians, and suggests soil as an alternative, or additional, explanation for deer vegetation legacy effects. We suggest that the reliance on phyto-indicators of deer browsing effects may overestimate the effects of browsing if those species are also limited by unfavourable soil conditions. Future research should consider study designs that address the complexity of deer forest interactions, especially in areas with complex site-vegetation histories.

Investigating the impact of the diseases of despair in Appalachia.

IntroductionAppalachia is one of the regions most significantly impacted by the opioid crisis. This study investigated mortality due to diseases of despair within the Appalachian Region, with an additional focus on deaths attributable to opioid overdose.MethodsDiseases of despair include: alcohol, prescription drug and illegal drug overdose, suicide, and alcoholic liver disease/cirrhosis of the liver. Mortality data from the National Center for Health Statistics (NCHS) National Vital Statistics System (NVSS) Multiple Cause of Death database were analyzed for this study, focusing on individuals aged 15–64.ResultsOver the past two decades, the mortality rate due to diseases of despair has been increasing across the United States, but the gap has widened between the Appalachian Region and the rest of the nation. In 2017, the combined diseases of despair mortality rate was 45% higher in the Appalachian Region than the non-Appalachian United States. When looking at just overdose mortality, this disparity grows to 65% higher in the Appalachian Region. Within the Appalachian region disparities are most notable in the Central and North Central Appalachian subregions, among males, and among individuals age 45 to 54.DiscussionThese findings document the scale and scope of the problem in Appalachia and highlight the need for additional research and discussion in terms of effective interventions, policies, and strategies to address these diseases of despair. Over the past two decades, mortality from overdose, suicide, and alcoholic liver diseases/cirrhosis has increased across the United States, but the disparity between Appalachia and the non-Appalachian U.S. continues to grow.

Constraints from geochemistry and oxygen isotopes for the hydrothermal origin of orthoamphibole mafic gneiss in the New Jersey Highlands, north-central Appalachians, USA

Rare exposures of orthoamphibole mafic (Oam) gneiss of Mesoproterozoic age in the north-central Appalachians are confined to the northwestern New Jersey Highlands where they form thin lens-shaped bodies composed of gedrite and sparse anthophyllite, oligoclase (An13–An20), biotite, magnetite, and local fluorapatite, rutile, and ilmenite. The gneiss is penetratively foliated and has sharp, conformable contacts against enclosing supracrustal paragneiss and marble. Orthoamphibole mafic gneiss is characterized by low SiO2 (48±2.5wt%), CaO (1.9±1.3wt%), and high Al2O3 (18±1.2wt%), Fe2O3 (10.5±1.6wt%), and MgO (12±2.3wt%). Trace element abundances overlap those of unaltered amphibolites in the study area and, coupled with δ18O values of 9.45±0.6‰ (VSMOW) from gedrite separates, support an origin from a basalt protolith.The geochemical and isotopic data are consistent with the formation of Oam gneiss through sea floor hydrothermal alteration of basalt at low temperature of 150–200°C. Mass-balance calculations indicate gains during alteration mainly in MgO and Al2O3 and losses in CaO, Sr, and light rare earth elements. Our results are compatible with the pre-metamorphic alteration of the basalt protoliths through chloritization and plagioclase dissolution that produced a Mg-rich and Ca-poor rock. Subsequent metamorphism of this chlorite-rich rock to the current mineral assemblage of Oam gneiss took place at ca. 1045Ma, during the Ottawan phase of the Grenvillian Orogeny. The close spatial association in the study area of Oam gneiss bodies and sulfide occurrences suggests an affinity to the style of mineralization associated with volcanogenic massive sulfide (VMS)-type deposits.

Non-Association of Methylenetetrahydrofolate Reductase (MTHFR) Polymorphisms with Homocysteine Levels, Venous or Arterial Thromboses in 1,141 North-Central Appalachian Patients

&lt;p class="cco-body"&gt;&lt;strong&gt;&lt;span lang="EN-GB"&gt;Objectives&lt;/span&gt;&lt;/strong&gt;&lt;span lang="EN-GB"&gt;: MTHFR polymorphism testing has been used by clinicians for thrombophilia risk assessment. We questioned the utility of such testing.&lt;/span&gt;&lt;/p&gt;&lt;p class="cco-body"&gt;&lt;strong&gt;&lt;span lang="EN-GB"&gt;Methods&lt;/span&gt;&lt;/strong&gt;&lt;span lang="EN-GB"&gt;: 1,141 patients age 18 and above had MTHFR testing for both C677T and A1298C polymorphisms, 2006 through 2012. Available plasma homocysteine levels were obtained and ICD-9 billing codes were grouped to identify venous or arterial clots in these patients.&lt;/span&gt;&lt;/p&gt;&lt;p class="cco-body"&gt;&lt;strong&gt;&lt;span lang="EN-GB"&gt;Results&lt;/span&gt;&lt;/strong&gt;&lt;span lang="EN-GB"&gt;: 901 women and 240 men were tested; median age in women was 33 years (range 18-86); median age in men was 47 years (range 18-83). County of residence mapping confirmed that this MTHFR tested population was from north-central Appalachia. Only 144 (13%) of the 1,141 patients had no polymorphism at either the C677T or the A1298C locus; only 4 patients (0.4%) had 3 or more polymorphisms; 993 patients (87%) had either one or two polymorphisms. &lt;/span&gt;&lt;/p&gt;&lt;p class="cco-body"&gt;&lt;span lang="EN-GB"&gt;We found polymorphism frequency pattern similar in both sexes. Although men had higher homocysteine levels, MTHFR polymorphisms did not associate with homocysteine levels in either sex. In 901 women tested, the ICD-9 coded incidence of arterial clots was 20%, and of venous clots was 21%; in 240 men tested, the incidence of arterial clots was 48% and of venous clots was 40%. MTHFR polymorphisms did not associate with arterial or venous clots in either sex. &lt;/span&gt;&lt;/p&gt;&lt;p class="cco-body"&gt;&lt;span lang="EN-GB"&gt;Based on CPT billing codes, a minimal cost estimate was $137,000 for performing these 1,141 MTHFR tests.&lt;/span&gt;&lt;/p&gt;&lt;p class="cco-body"&gt;&lt;strong&gt;&lt;span lang="EN-GB"&gt;Conclusions&lt;/span&gt;&lt;/strong&gt;&lt;span lang="EN-GB"&gt;: MTHFR testing was costly and did not add useful information during thrombophilia evaluation in this patient population. &lt;/span&gt;&lt;/p&gt;

Geochemical and Sr–Nd isotopic constraints on the mantle source of Neoproterozoic mafic dikes of the rifted eastern Laurentian margin, north-central Appalachians, USA

Abundant and widely distributed unmetamorphosed mafic dikes intrude Mesoproterozoic rocks of the New Jersey Highlands. The age of the dikes is imprecisely known but interpreted to fall between 615 and 576 Ma, which is consistent with the range of ages of mafic dikes from Labrador and Nova Scotia south to Pennsylvania that were emplaced along the rifted eastern Laurentian margin. New Jersey Highlands dikes are a few cm to 18 m wide and have lengths of as much as several km. They have sharp, largely discordant contacts against enclosing Mesoproterozoic rocks and aphanitic chilled margins that grade into coarser grained interiors. Columnar joints are present locally and suggest emplacement at a shallow crustal level. Geochemical compositions of the dikes range from alkalic to less common tholeiitic basalt having generally high TiO 2 , P 2 O 5 , Zr, Nb, Y, and La/Yb, and low MgO, Cr, and Ni. TiO 2 contents define high-Ti and low-Ti dikes that differ in high field strength elements (HFSE) and light rare earth elements (LREE) but overlap in abundances of most other elements. Dike magma evolved in an ascending mantle plume of OIB-like asthenosphere from enriched higher TiO 2 compositions to more depleted lower TiO 2 compositions. Subtle differences in the dike compositions are due to variations in the amount of partial melting within the plume and the depth of melt segregation. Sr–Nd isotope values of both dike compositions overlap and are characterized by ε Nd (T) of + 1.5 to + 3.8 and initial 87 Sr/ 86 Sr ranging from 0.7032 to 0.7077. Higher Sr isotope ratios are interpreted as resulting from local interaction of the dike magma with heterogeneous, high 87 Sr/ 86 Sr lithospheric mantle having EMI or EMII-like geochemical characteristics. Dikes form tabular structures that have long segments striking an average of N44°E and short segments striking about east–west. Their regional geometries form right-stepping, rhomb-shaped patterns due to emplacement into rift-related dilational fractures likely formed through a combination of southeast-directed extension and strike-slip shear stresses. Geochemical compositions of the dikes are the same regardless of their structural trend or location implying they formed during a single magmatic event. They, along with other mafic dikes in the north-central Appalachians, were emplaced in a within-plate tectonic setting along the rifted margin of eastern Laurentia, prior to opening of the Iapetus Ocean. • Mantle sources of Neoproterozoic mafic dikes were modeled from Sr–Nd isotopes and geochemistry. • Dikes formed from partial melting of a garnet-free, enriched OIB-like source. • Geochemical similarity to other regional Neoproterozoic dikes along the eastern Laurentian margin • Dikes emplaced from single magmatic event during rifting that formed the Iapetus Ocean

Stream Macroinvertebrate Response Models for Bioassessment Metrics: Addressing the Issue of Spatial Scale

We developed independent predictive disturbance models for a full regional data set and four individual ecoregions (Full Region vs. Individual Ecoregion models) to evaluate effects of spatial scale on the assessment of human landscape modification, on predicted response of stream biota, and the effect of other possible confounding factors, such as watershed size and elevation, on model performance. We selected macroinvertebrate sampling sites for model development (n = 591) and validation (n = 467) that met strict screening criteria from four proximal ecoregions in the northeastern U.S.: North Central Appalachians, Ridge and Valley, Northeastern Highlands, and Northern Piedmont. Models were developed using boosted regression tree (BRT) techniques for four macroinvertebrate metrics; results were compared among ecoregions and metrics. Comparing within a region but across the four macroinvertebrate metrics, the average richness of tolerant taxa (RichTOL) had the highest R2 for BRT models. Across the four metrics, final BRT models had between four and seven explanatory variables and always included a variable related to urbanization (e.g., population density, percent urban, or percent manmade channels), and either a measure of hydrologic runoff (e.g., minimum April, average December, or maximum monthly runoff) and(or) a natural landscape factor (e.g., riparian slope, precipitation, and elevation), or a measure of riparian disturbance. Contrary to our expectations, Full Region models explained nearly as much variance in the macroinvertebrate data as Individual Ecoregion models, and taking into account watershed size or elevation did not appear to improve model performance. As a result, it may be advantageous for bioassessment programs to develop large regional models as a preliminary assessment of overall disturbance conditions as long as the range in natural landscape variability is not excessive.

Topographic and Soil Constraints to Shale-Gas Development in the Northcentral Appalachians

Topographic and Soil Constraints to Shale-Gas Development in the Northcentral Appalachians

Early Trends in Landcover Change and Forest Fragmentation Due to Shale-Gas Development in Pennsylvania: A Potential Outcome for the Northcentral Appalachians

Worldwide shale-gas development has the potential to cause substantial landscape disturbance. The northeastern U.S., specifically the Allegheny Plateau in Pennsylvania, West Virginia, Ohio, and Kentucky, is experiencing rapid exploration. Using Pennsylvania as a proxy for regional development across the Plateau, we examine land cover change due to shale-gas exploration, with emphasis on forest fragmentation. Pennsylvania's shale-gas development is greatest on private land, and is dominated by pads with 1-2 wells; less than 10 % of pads have five wells or more. Approximately 45-62 % of pads occur on agricultural land and 38-54 % in forest land (many in core forest on private land). Development of permits granted as of June 3, 2011, would convert at least 644-1072ha of agricultural land and 536-894ha of forest land. Agricultural land conversion suggests that drilling is somewhat competing with food production. Accounting for existing pads and development of all permits would result in at least 649km of new road, which, along with pipelines, would fragment forest cover. The Susquehanna River basin (feeding the Chesapeake Bay), is most developed, with 885 pads (26 % in core forest); permit data suggests the basin will experience continued heavy development. The intensity of core forest disturbance, where many headwater streams occur, suggests that such streams should become a focus of aquatic monitoring. Given the intense development on private lands, we believe a regional strategy is needed to help guide infrastructure development, so that habitat loss, farmland conversion, and the risk to waterways are better managed.

U–Pb zircon geochronology of Mesoproterozoic postorogenic rocks and implications for post-Ottawan magmatism and metallogenesis, New Jersey Highlands and contiguous areas, USA

Postorogenic rocks are widespread in Grenville terranes of the north-central Appalachians where they form small, discordant, largely pegmatitic felsic intrusive bodies, veins, and dikes, and also metasomatic calcic skarns that are unfoliated and postdate the regional 1090 to 1030 Ma upper amphibolite- to granulite-facies metamorphism related to the Grenville (Ottawan) Orogeny. Zircons from magmatic and nonmagmatic rocks from northern New Jersey and southern New York were dated to provide information on the regional tectonomagmatic and metallogenic history following Ottawan orogenesis. We obtained U–Th–Pb zircon ages of 1004 ± 3 Ma for pegmatite associated with the 1020 ± 4 Ma Mount Eve Granite near Big Island, New York, 986 ± 4 Ma for unfoliated, discordant pegmatite that intrudes supracrustal marble at the Buckwheat open cut, Franklin, New Jersey, ∼990 Ma for a silicate-borate skarn layer in the Franklin Marble at Rudeville, New Jersey, and 940 ± 2 Ma for a calc-silicate skarn layer at Lower Twin Lake, New York. This new data, together with previously published ages of 1020 ± 4 to 965 ± 10 Ma for postorogenic rocks from New Jersey and southern New York, provide evidence of magmatic activity that lasted for up to 60 Ma past the peak of high-grade metamorphism. Postorogenic magmatism was almost exclusively felsic and involved relatively small volumes of metaluminous to mildly peraluminous melt that fractionated from an A-type granite parent source. Field relationships suggest the melts were emplaced along lithosphere-scale fault zones in the Highlands that were undergoing extension and that emplacement followed orogenic collapse by least 30 Ma. Postorogenic felsic intrusions correspond to the niobium–yttrium–fluorine (NYF) class of pegmatites of Černý (1992a). Geochronologic data provide a temporal constraint on late-stage hydrothermal activity and a metallogenic event in New Jersey at ∼990 to 940 Ma that mineralized pegmatites with subeconomic to economic deposits of magnetite ± U ± Th ± rare earth element (REE) and formed metasomatic calcic skarn bodies in marble and reactive carbonate rocks. Mineralization associated with this event overlaps the timing of pegmatite emplacement, suggesting a petrogenetic relationship. Coeval metallogeny at 975 to 950 Ma in the New York Hudson Highlands and 980 to 937 Ma in the Canadian Grenville Province implies that this event was widespread following the Ottawan phase of the Grenville Orogeny.

Fish Species Composition in Two Second-Order Headwater Streams in the North Central Appalachians Ecoregion

ABSTRACT Fish species composition was determined for two second-order headwater streams within the North Central Appalachians ecoregion in northern Pennsylvania. The two streams were widely spaced geographically (over 193 km apart) and occurred in different drainage systems. Streams were sampled in the spring and fall over two years (1996–98) yielding similar fish assemblages. A total of five species was collected. Mottled sculpin (Cottus bairdli), slimy sculpin (Cottus cognatus), brook trout (Salvetinus fontinalis), and brown trout (Salmo trutta) were the dominant adult fishes. Two creek chubs (Semotilus atromaculatus) were also collected. No significant differences were found in sculpin weight, sculpin length, salmonid length, or brook trout length between streams. Paired t-tests detected eight significant seasonal differences within sites. Brook trout and mottled sculpin lengths were significantly greater in fall versus spring, while the reverse was found with slimy sculpins. Catches per unit effort were similar between the two streams, yielding 8.46 and 8.07 fish per minute of electrofishing. Both streams were very similar in faunal assemblages attributed to small, coldwater, high quality headwater streams in other regions.

A geologic history of the north-central Appalachians; Part 3, The Alleghany Orogeny

The north-central Appalachians occupy a critical position within the 3000+ km-long Appalachian orogen, lying southwest of the boundary between the central and northern Appalachians (CNAB). The one-billion-year-long history of tectonic activity in eastern Laurentia includes the creation and evolution of the Appalachian orogen during the Paleozoic and the Mesozoic transformation of the orogen into a passive margin during Pangea9s disassembly. A most important ingredient in the evolution of the orogen was the Alleghany orogeny, which was driven by the convergence and collision between Laurentia (Laurussia) and West Gondwana (Africa). The Alleghany orogeny in the central and southern Appalachians was a decollement tectonism that involved a larger part of eastern Laurentia than had the previous three orogenies. The fundamental element was a very low-angle thrust (decollement) that originated in mid-crustal levels east of the presently-exposed Appalachians and rose westwardly to progressively higher levels in the upper crust and the supra-crustal Paleozoic section. Alleghany deformation was widely developed in the hanging-wall block (allochthon), primarily in the form of thrust faults and fold-and-thrust structures, both of which splayed upward from the basal decollement. The youngest manifestations of the Alleghany orogeny were northeast-trending strike-slip faults and dextral shear zones in the Piedmont. In the north-central Appalachians, the exposed allochthon consists of two parts: the sedimentary externides (Appalachian Plateau and Valley and Ridge provinces) and the crystalline externides (Reading Prong, Blue Ridge belt, and Piedmont province). Long, thrust-cored anticlines predominate in the sedimentary externides. A widespread layer-parallel shortening preceded the folding; it is largely coaxial with the folding but extends considerably farther to the northwest toward the craton. It is hypothesized that the folding developed in reverse order, sequentially from the northwest to the southeast. The crystalline externides are dominated by low-angle thrust faults and upright folds trending east-northeast. The first-order Valley and Ridge folds on the northwest side acted as a buttress and diverted the crystalline externides rocks north-northwestwardly, onto the topographic low area over the Anthracite region. This thrusting of the crystalline externides caused anthracitization of the coals within the Pennsylvanian rocks there. Metamorphism and magmatism were significant events during the earlier phase of the Alleghany orogeny in the southern Appalachians. Whatever magmatism and medium-to high-grade metamorphism developed in the north-central Appalachians are in the covered internides to the southeast. The Alleghany orogeny of the north-central Appalachians occurred during the Early Permian. Erosion of anticlinal crests probably began as the folds grew, with accumulation of this locally-derived sediment in the intervening synclines. A regional alluvial plain coalesced above the partially-eroded externides structures as erosion of the pre-Alleghany highland and the Alleghany hinterland mountains continued to the southeast, spreading sediment to the northwest. This erosion and northwest transport probably persisted, with diminishing intensity, throughout the remainder of the Permian and into the Mesozoic, and changed only with the beginning of crustal extension during the Late Triassic.

A Geologic History of the North-Central Appalachians; Part 2, the Appalachian Basin From the Silurian Through the Carboniferous

The north-central Appalachians occupy a critical position within the 3000+ km-long Appalachian orogen, lying southwest of the boundary between the central and northern Appalachians (CNAB). The one-billion-year-long history of tectonic activity in the north-central Appalachians includes the assembly and breakup of a late Proterozoic supercontinent, the creation and evolution of the Appalachian orogen during the Paleozoic, and the Mesozoic transformation of the active orogen into a passive margin during Pangea9s disassembly. An important part of the Middle and Late Paleozoic history is the formation and growth of the Appalachian basin, an enormous, elongate continental basin lying cratonward of the active Appalachian internides along Laurentia9s eastern margin. The Appalachian basin developed out of the Taconic orogeny, the second of the four orogenies that formed and modified the character of the Appalachian orogen. Prior to the Taconic orogeny, the eastern margin of Laurentia consisted of a broad carbonate shelf facing the Theic Ocean. The Taconic orogeny obduced various Theic components, including microcontinents, magmatic arcs, and accretionary prisms, onto the carbonate shelf. The resulting Taconic highlands formed a topographic barrier between Theia and the craton9s interior. Because tectonic activity in the internides continued more or less throughout the remainder of the Paleozoic, the Appalachian basin never had a direct connection with Theia. The coarse-grained molasse from the newly uplifted Taconic highland spread westward over most of the basin during the Early Silurian. Carbonate deposition gradually encroached eastward over the basin as the siliciclastic input from the southeast waned. A resurgence in the earliest Late Silurian, perhaps related to orogenesis in Newfoundland and the Maritimes, expanded the clastic wedge somewhat. Before long, however, carbonate deposition once again dominated most of the north-central basin for the remainder of the Silurian and into the Early Devonian. The Early-to-Middle Devonian Acadian orogeny began introducing siliciclastic material into the eastern part of the Appalachian basin, thereby ending the largely paralic environment that persisted from the Late Silurian. A number of deltas formed around local sediment-input centers during the Middle Devonian. Continued uplift and/or orogenesis must have continued into the Late Devonian because a vast amount of terrigenous sediment was introduced into the Appalachian basin to form the vast Upper Devonian Catskill delta. Although the principal tectonic activity appears to have centered in New England, the large volume of sediment input suggests that orogenesis may have extended southward to the north-central Appalachians. However, direct evidence of actual Acadian deformation and metamorphism is lacking at this latitude. The north-central Appalachian basin underwent a significant change during the Carboniferous. Prior to this time, the shoreline shifted laterally through transgressions and regressions largely as a function of sediment input and regional subsidence. In the Carboniferous, vertical movements in the basin became more important. During the Early Carboniferous, much of the Mauch Chunk delta was eroded in the central and western parts of the basin. At the end of the Early Carboniferous, an unconformity truncated progressively older rocks to the north toward New York. New sediment transport patterns and depositional environments within the basin during the Late Carboniferous probably reflect significant topographic and tectonic changes, not only in the hinterland, but in the basin itself, perhaps in conjunction with climatic changes. Extensive interfluvial swamps on a lower delta plain accumulated thick organic deposits which would become coal. This delta plain graded southwestward into tidal and marine environments. The Alleghany orogeny in the Early Permian interrupted deposition in much of the north-central Appalachian basin and profoundly altered its structure.

A geologic history of the north-central Appalachians; Part 1, Orogenesis from the Mesoproterozoic through the Taconic Orogeny

The north-central Appalachians lie just southwest of the boundary between the central/southern and northern Appalachians, occupying a critical position within the 3000+ km-long Appalachian orogen. The history of tectonic activity in the north-central Appalachians spans more than one billion years, from the assembly and breakup of a Neoproterozoic supercontinent, through active orogenesis during Laurentia9s Paleozoic northward journey off the western margin of West Gondwana, to the Mesozoic transformation of the active orogen into a passive margin during Pangea9s disassembly. The major tectonic events include five compressional orogenies and two extensional episodes: 1. The late Mesoproterozoic Grenville orogeny assembled several continental masses into the Neoproterozoic supercontinent, Rodinia. It was the most widespread but now least exposed tectonism, and rocks involved in this event underlie as basement most of the exposed north-central Appalachians. Large fragments of Laurentian Grenville rock were subsequently broken off and incorporated in later Appalachian orogenesis. 2. Crustal extension and rifting late in the Neoproterozoic and into the earliest Cambrian separated Laurentia from West Gondwana, thereby forming the intervening Theic ocean and two continental rifts on Laurentia9s eastern margin, the Catoctin rift and, later in the Middle? to Late Cambrian, the so-called Rome trough. The initial siliciclastic sedimentation on the margin migrated westward through time onto the craton, supplanted by a thick and increasingly wide carbonate shelf on Laurentia9s eastern margin. Two microcontinents of Grenville-age, non-Laurentian(?) continental rock became positioned east of Laurentia, thereby creating the Octoraro sea as an arm of Theia. 3. In Theia, east of the two microcontinents, magmatic arcs developed over a subduction zone late in the Cambrian. Convergence within Theia caused the Potomac orogeny, which obduced the arcs (Wilmington Complex, Cecil Amalgamate) over the microcontinents and associated Theic deposits (including accretionary wedge sediments). 4. Continued westward convergence collapsed the Octoraro sea, producing the Middle to Late Ordovician Taconic orogeny in which the Potomac-deformed magmatic arcs and associated Theic elements were obduced onto the Laurentian continental margin. This obduction: drowned the carbonate shelf with siliciclastic sediments (Martinsburg Formation); drove continental rise and basinal deposits over the carbonate shelf on the Martic thrust; slid the Hamburg klippe onto the shelf; and accreted the Potomac package of microcontinent/arc/basinal-sediments onto the Laurentian margin. This orogeny transformed the broad Early Paleozoic carbonate shelf into the Appalachian basin that persisted throughout the Middle and Late Paleozoic. 5. The Middle Devonian Acadian orogeny ended the largely paralic environment that dominated the Appalachian basin during the Late Silurian. Active orogenesis in New England probably extended southward to the north-central Appalachians, because a vast amount of terrigenous sediment was introduced into the Appalachian basin to form the Catskill delta; however, evidence of actual Acadian deformation and metamorphism is lacking at this latitude. These presumed internal Acadides have yet to be found. 6. The convergence of West Gondwana and Laurentia during the Late Carboniferous and earliest Permian produced the Permian Alleghany orogeny in the north-central Appalachians. This widespread decollement tectonism directly affected a larger area of the presently exposed central and southern Appalachians than any earlier Paleozoic tectonic event. An early layer-parallel shortening phase gave way to a fold-thrust development above a basal decollement. This Alleghany fold-and-thrust tectonism created long, arcuate folds in the Appalachian basin. Late in the Alleghany orogeny, rock thrust northward over the Carboniferous rocks in the Anthracite region of northeastern Pennsylvania caused anthracitization of the underlying coals. The internal Alleghanides are not presently exposed. 7. Crustal extension in the Late Triassic and Early Jurassic produced numerous local, closed basins along eastern North America. Igneous intrusions and effusions marked the beginning of the Jurassic. By the end of the Early Jurassic, horizontal crustal rebound in response to opening of the Atlantic Ocean rotated the basins by crustal inversion, which folded some within-basin rocks and produced a prominent topographic ridge along the Piedmont, up-dip of the basins. Subsequent erosion of this Piedmont ridge and other parts of the Appalachian orogen fed large volumes of sediment to offshore basins during the remainder of the Mesozoic and throughout the Cenozoic. Each of these orogenies affected most of the Appalachian orogen. The tectonic expression of each orogeny varied along and across the orogen. The elements and structural bodies involved in each also varied along strike. However, many common elements persist from one part of the orogen to another; only a few features are singular in time and space. The tectonic boundary between the central and northern Appalachians is one of these singular features-it is solely an Alleghanian artifact.

A geologic history of the north-central Appalachians; Part 2, The Appalachian Basin from the Silurian through the Carboniferous

The north-central Appalachians occupy a critical position within the 3000+ km-long Appalachian orogen, lying southwest of the boundary between the central and northern Appalachians (CNAB). The one-billion-year-long history of tectonic activity in the north-central Appalachians includes the assembly and breakup of a late Proterozoic supercontinent, the creation and evolution of the Appalachian orogen during the Paleozoic, and the Mesozoic transformation of the active orogen into a passive margin during Pangea9s disassembly. An important part of the Middle and Late Paleozoic history is the formation and growth of the Appalachian basin, an enormous, elongate continental basin lying cratonward of the active Appalachian internides along Laurentia9s eastern margin. The Appalachian basin developed out of the Taconic orogeny, the second of the four orogenies that formed and modified the character of the Appalachian orogen. Prior to the Taconic orogeny, the eastern margin of Laurentia consisted of a broad carbonate shelf facing the Theic Ocean. The Taconic orogeny obduced various Theic components, including microcontinents, magmatic arcs, and accretionary prisms, onto the carbonate shelf. The resulting Taconic highlands formed a topographic barrier between Theia and the craton9s interior. Because tectonic activity in the internides continued more or less throughout the remainder of the Paleozoic, the Appalachian basin never had a direct connection with Theia. The coarse-grained molasse from the newly uplifted Taconic highland spread westward over most of the basin during the Early Silurian. Carbonate deposition gradually encroached eastward over the basin as the siliciclastic input from the southeast waned. A resurgence in the earliest Late Silurian, perhaps related to orogenesis in Newfoundland and the Maritimes, expanded the clastic wedge somewhat. Before long, however, carbonate deposition once again dominated most of the north-central basin for the remainder of the Silurian and into the Early Devonian. The Early-to-Middle Devonian Acadian orogeny began introducing siliciclastic material into the eastern part of the Appalachian basin, thereby ending the largely paralic environment that persisted from the Late Silurian. A number of deltas formed around local sediment-input centers during the Middle Devonian. Continued uplift and/or orogenesis must have continued into the Late Devonian because a vast amount of terrigenous sediment was introduced into the Appalachian basin to form the vast Upper Devonian Catskill delta. Although the principal tectonic activity appears to have centered in New England, the large volume of sediment input suggests that orogenesis may have extended southward to the north-central Appalachians. However, direct evidence of actual Acadian deformation and metamorphism is lacking at this latitude. The north-central Appalachian basin underwent a significant change during the Carboniferous. Prior to this time, the shoreline shifted laterally through transgressions and regressions largely as a function of sediment input and regional subsidence. In the Carboniferous, vertical movements in the basin became more important. During the Early Carboniferous, much of the Mauch Chunk delta was eroded in the central and western parts of the basin. At the end of the Early Carboniferous, an unconformity truncated progressively older rocks to the north toward New York. New sediment transport patterns and depositional environments within the basin during the Late Carboniferous probably reflect significant topographic and tectonic changes, not only in the hinterland, but in the basin itself, perhaps in conjunction with climatic changes. Extensive interfluvial swamps on a lower delta plain accumulated thick organic deposits which would become coal. This delta plain graded southwestward into tidal and marine environments. The Alleghany orogeny in the Early Permian interrupted deposition in much of the north-central Appalachian basin and profoundly altered its structure.

Ages of Detrital White Mica from Devonian-Pennsylvanian Strata of the North Central Appalachian Basin: Dominance of the Acadian Orogen as Provenance

Detrital micas (mostly white mica) from Devonian-Middle Pennsylvanian strata of the north central Appalachian Basin at 12 sites were dated by conventional K/Ar. Three small pilot samples were less precisely dated than the rest. The youngest stratigraphic sample of Pennsylvanian depositional age (Alleghenian) produced 414/Ma muscovite and 361 Ma biotite. Excluding this sample, a narrower 35 m.y. range of Early to Middle Devonian detrital dates (from 406-371 Ma) were obtained. The precise dates from the proximal and distal Catskill wedge represent an even narrower 19 m.y. span (406-387 Ma), which is entirely Early Devonian and only approximately 30 m.y. older than the Late Devonian-Early Mississippian time of deposition. All these detrital dates from pre-Alleghenian samples correspond to reported primary ages of crystallization, or cooling therefrom, of regional metamorphism and plutonism during the Acadian orogeny, believed to be the principal Paleozoic orogeny in New England and eastern Canada. The dominance of the Acadian Orogen as a source region is evident. Even though these are conventional K/Ar dates of multi-grain separates, the mean provenance ages from so many individual samples are so close to the age of deposition to preclude almost any Precambrian contribution from either the nearby Canadian Shield or the uplifted cores of the orogen. They imply Acadian sources dominated considerably over Taconic ones. Furthermore, our results for the Mauch Chunk (377 Ma), Pottsville (371 Ma), and our youngest (Alleghenian) sample suggest that the Acadian Orogen persisted as the major provenance for post-Catskill clastic pulses that prograded into the central Appalachian Basin at least up until Middle Pennsylvanian time.