Geology topics

Research about North Carolina, Tennessee, Virginia

Source-linked reports with geographic coverage including North Carolina, Tennessee, Virginia.

8 recordsLinked to original sources

USGS2026

Resource selection for an endangered flying squirrel, Glaucomys sabrinus coloratus, in a montane sky-island system

Geographically isolated endemic species and their habitats in montane systems face stressors of rapid climate change as well as legacy and contemporary land use change. In the case of endangered species in fragmented terrestrial montane habitats, effectively sky-islands, insight into habitat use and resource selection is vital for effective conservation measures. We created a resource selection function using a long-term dataset of multiple monitoring techniques (live-trapping, radio-telemetry, camera traps, acoustic detectors, and nest boxes) across a wide geographical range for an endangered subspecies, the Carolina northern flying squirrel Glaucomys sabrinus coloratus , in a vulnerable high-elevation sky-island boreal forest ecosystem in the southeastern USA. Using fine-scale habitat and topographic coverage on 8 sky-islands, we employed various models to capture nuanced habitat relationships that can better inform the conservation of remaining subpopulations as well as other endemic species that share their habitat. Our analyses confirmed that red spruce Picea rubens -Fraser fir Abies fraseri was the most significant habitat component for determining Carolina northern flying squirrel presence, but that relationships varied somewhat among sky-islands owing to differences in extent, elevation range, and forest community configurations. Further, we found that solely using nest boxes, as previously reported, to create a resource selection function biased the results, but that nest boxes remain an effective tool for overcoming habitat fragmentation and decreasing exposure to antagonistic species.

North Carolina, Tennessee, Virginia↗

USGS2023

Potential effects of climate change on Appalachian stoneflies ( Remenus kirchneri , Acroneuria kosztarabi , and Tallaperla lobata )

Plecoptera (stoneflies) are an order of insects where most species rely on clean, fast-moving freshwater for an aquatic larval stage followed by a short terrestrial adult stage. Most species of Plecoptera seem to be restricted to specific stream types and thermal regimes. Climate-driven changes are likely to alter stream temperatures and flow, resulting in physiological stress, reduced reproductive success, and possibly latitudinal or elevational distribution shifts. This report focuses on climate projections and the resulting ecological effect for three species of Appalachian stoneflies: Remenus kirchneri , Acroneuria kosztarabi , and Tallaperla lobata . Although species-specific information is sparse for these three species, climate studies for other Plecoptera spp. are applicable. In the focal region, temperature is increasing and likely leading to increased stream temperatures. In response, Plecoptera spp. will likely experience physiological stress from increasing metabolic rates and energy demands concurrent with changing food quality and access. Warming temperatures and decreased larval energy stores are likely to contribute to lower adult body size and longevity, thus decreasing reproductive success. Whereas projected changes to precipitation and runoff are less certain, under drier future climate projections, decreased streamflow may further stress larval Plecoptera. Remenus kirchneri , A. kosztarabi , and T. lobata will likely retain stable permanent stream habitats for the analyzed future (2006–99). Changing climate is of particular concern for mountaintop species R. kirchneri and T. lobata because they may be unable to track shifts in suitable climate and habitat.

North Carolina, Tennessee, Virginia↗

USGS2023

Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus Ocean, Blue Ridge, VA–NC–TN

Recent field and geochronological studies in eight 7.5-minute quadrangles near Mount Rogers in Virginia, North Carolina and Tennessee recognize (1) important stratigraphic and structural relationships for the Neoproterozoic Mount Rogers and Konnarock Formations, and the northeast end of the Mountain City window; (2) the separation of Mesoproterozoic rocks of the Blue Ridge into three age groups; and (3) the timing and emplacement of the Blue Ridge thrust sheet. The study area includes folded and faulted Paleozoic strata of the Valley and Ridge in the northwest juxtaposed by metamorphic and igneous rocks of the Blue Ridge to the southeast. In the Valley and Ridge, Cambrian to Middle Ordovician carbonate and clastic rocks are exposed in a syncline in the Pulaski thrust sheet; these rocks are overridden by the Blue Ridge thrust sheet. The northeast end of the Mountain City window is interpreted as a simple window; the Stone Mountain fault is folded and continues as the Iron Mountain fault on the NW-side of the window. The Stone Mountain fault does not exist at the surface to the NE near the Razor Ridge volcanic center. Instead, a continuous section of Proterozoic gneisses, Mount Rogers Formation, Konnarock Formation and Chilhowee Group is now recognized. Rhyolites of the Mount Rogers Formation range from 760–749Ma, with detrital zircon age populations from associated volcaniclastic rocks indicating magmatism and rifting began by ~780 Ma. Rhyolite outliers in the Konnarock Formation and a change from rift-related clastic rocks of the Mount Rogers Formation transitioning to maroon laminites, mudstones and laminites with dropstones, suggest that the Konnarock Formation may be as old as ~751 Ma. Mesoproterozoic crystalline rocks of the Blue Ridge, previously referred to as the Cranberry Gneiss, are distinguished based on field relationships and SHRIMP U–Pb zircon geochronology: (1) ~1.33 Ga pre-Grenvillian crust; (2) 1190–1140 Ma granitoids (early magmatic suite); and (3) 1075–1030 Ma granitoids (late magmatic suite). Multiple greenschist-facies high-strain zones, including the 2–11 km wide Fries high-strain zone, occur in the Blue Ridge thrust sheet. Fabrics across the Fries and Gossan Lead faults have similar orientations and NW–directed contractional deformation. 40 Ar/ 39 Ar hornblende, muscovite, and K-feldspar ages indicate the western and eastern Blue Ridge had different thermal histories. The eastern Blue Ridge (Gossan Lead thrust sheet) experienced a 360–340 Ma amphibolite facies event prior to juxtaposition with the western Blue Ridge. 40 Ar/ 39 Ar muscovite ages in western Blue Ridge rocks document greenschist facies metamorphism and deformation and emplacement of the Blue Ridge thrust sheet at ~340 Ma; the Catface and Fries faults are tentatively interpreted to be contemporaneous. After initial emplacement of the Blue Ridge thrust sheet at ~340 Ma, shortening was accommodated by westward translation along the basal decollement, which carried the Blue Ridge thrust sheet to its current position.

North Carolina, Tennessee, Virginia↗

USGS2016

Predictive habitat models derived from nest-box occupancy for the endangered Carolina northern flying squirrel in the southern Appalachians

In the southern Appalachians, artificial nest-boxes are used to survey for the endangered Carolina northern flying squirrel (CNFS; Glaucomys sabrinus coloratus ), a disjunct subspecies associated with high elevation (>1385 m) forests. Using environmental parameters diagnostic of squirrel habitat, we created 35 a priori occupancy models in the program PRESENCE for boxes surveyed in western North Carolina, 1996-2011. Our best approximating model showed CNFS denning associated with sheltered landforms and montane conifers, primarily red spruce Picea rubens . As sheltering decreased, decreasing distance to conifers was important. Area with a high probability (>0.5) of occupancy was distributed over 18662 ha of habitat, mostly across 10 mountain ranges. Because nest-box surveys underrepresented areas >1750 m and CNFS forage in conifers, we combined areas of high occupancy with conifer GIS coverages to create an additional distribution model of likely habitat. Regionally, above 1385 m, we determined that 31795 ha could be occupied by CNFS. Known occupied patches ranged from

North Carolina, Tennessee, Virginia↗

USGS2014

Measurements of HFC-134a and HCFC-22 in groundwater and unsaturated-zone air: implications for HFCs and HCFCs as dating tracers

A new analytical method using gas chromatography with an atomic emission detector (GC–AED) was developed for measurement of ambient concentrations of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) in soil, air, and groundwater, with the goal of determining their utility as groundwater age tracers. The analytical detection limits of HCFC-22 (difluorochloromethane, CHClF 2 ) and HFC-134a (1,2,2,2-tetrafluoroethane, C 2 H 2 F 4 ) in 1 L groundwater samples are 4.3 × 10 − 1 and 2.1 × 10 − 1 pmol kg − 1 , respectively, corresponding to equilibrium gas-phase mixing ratios of approximately 5–6 parts per trillion by volume (pptv). Under optimal conditions, post-1960 (HCFC-22) and post-1995 (HFC-134a) recharge could be identified using these tracers in stable, unmixed groundwater samples. Ambient concentrations of HCFC-22 and HFC-134a were measured in 50 groundwater samples from 27 locations in northern and western parts of Virginia, Tennessee, and North Carolina (USA), and 3 unsaturated-zone profiles were collected in northern Virginia. Mixing ratios of both HCFC-22 and HFC-134a decrease with depth in unsaturated-zone gas profiles with an accompanying increase in CO 2 and loss of O 2 . Apparently, ambient concentrations of HCFC-22 and HFC-134a are readily consumed by methanotrophic bacteria under aerobic conditions in the unsaturated zone. The results of this study indicate that soils are a sink for these two greenhouse gases. These observations contradict the previously reported results from microcosm experiments that found that degradation was limited above-ambient HFC-134a. The groundwater HFC and HCFC concentrations were compared with concentrations of chlorofluorocarbons (CFCs, CFC-11, CFC-12, CFC-113) and sulfur hexafluoride (SF 6 ). Nearly all samples had measured HCFC-22 or HFC-134a that were below concentrations predicted by the CFCs and SF6, with many samples showing a complete loss of HCFC-22 and HFC-134a. This study indicates that HCFC-22 and HFC-134a are not conservative as environmental tracers and leaves in question the usefulness of other HCFCs and HFCs as candidate age tracers.

North Carolina, Tennessee, Virginia↗

USGS2014

Developing a topographic model to predict the northern hardwood forest type within Carolina northern flying squirrel ( Glaucomys sabrinus coloratus ) recovery areas of the southern Appalachians

The northern hardwood forest type is an important habitat component for the endangered Carolina northern flying squirrel (CNFS; Glaucomys sabrinus coloratus ) for den sites and corridor habitats between boreo-montane conifer patches foraging areas. Our study related terrain data to presence of northern hardwood forest type in the recovery areas of CNFS in the southern Appalachian Mountains of western North Carolina, eastern Tennessee, and southwestern Virginia. We recorded overstory species composition and terrain variables at 338 points, to construct a robust, spatially predictive model. Terrain variables analyzed included elevation, aspect, slope gradient, site curvature, and topographic exposure. We used an information-theoretic approach to assess seven models based on associations noted in existing literature as well as an inclusive global model. Our results indicate that, on a regional scale, elevation, aspect, and topographic exposure index (TEI) are significant predictors of the presence of the northern hardwood forest type in the southern Appalachians. Our elevation + TEI model was the best approximating model (the lowest AICc score) for predicting northern hardwood forest type correctly classifying approximately 78% of our sample points. We then used these data to create region-wide predictive maps of the distribution of the northern hardwood forest type within CNFS recovery areas.

North Carolina, Tennessee, Virginia↗

USGS2000

Water quality in the upper Tennessee River basin, Tennessee, North Carolina, Virginia, and Georgia 1994-98

This report summarizes major findings about water quality in the upper Tennessee River basin that emerged from an assessment conducted between 1994 and 1998 by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Water quality is discussed in terms of local and regional issues and compared to conditions found in all 36 NAWQA study areas, called study units, assessed to date. Findings are also explained in the context of selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. Finally, this report includes information about the status of aquatic communities and the condition of in-stream habitats as elements of a complete water-quality assessment.

North Carolina, Tennessee, Virginia↗

USGS1965

Age and metamorphism of some massive sulfide deposits in Virginia, North Carolina and Tennessee

Isotopic ages of vein and wall-rock samples have been determined on five massive sulflde deposits of the southern Appalachians. Vein mineral ages of about 1100 m.y. indicate that some ore bodies formed at least as early as the Grenville metamorphism, and probably soon after the formation of the enclosing gneiss and schist. Present textures of the ore were formed during subsequent metamorphic periods at about 450 m.y. and 300 to 330 m.y. ago.

North Carolina, Tennessee, Virginia↗