No description available.

Lower Pennsylvanian siliciclastic sedimentary rocks of the central Appalachian Basin consist predominantly of nonmarine, coal-bearing facies that developed within a fluvio-estuarine, trunk-tributary drainage system in a foreland-basin setting. Sheet-like, sandstone-mudstone bodies (up to 100 km wide and 70 m thick) developed in an axial trunk drainage system, whereas channel-like, sandstone-mudstone bodies (up to several km wide and 30 m thick) developed in tributaries oriented transverse to the thrust front. The origin of these strata has been debated largely because the paleogeomorphology and facies architecture of the New River Formation (NRF) are poorly understood. A sequence stratigraphic framework for the NRF, based on a combination of outcrop mapping and subsurface well-log analysis, reveals: 1) regionally significant erosional surfaces along the bases of sheet-like and channel-like sandstone bodies (sequence-boundaries), 2) fluvial- to estuarine-facies transitions (marine flooding surfaces), 3) erosionally based, framework-supported, quartz-pebble conglomerates (ravinement beds), and 4) regionally traceable, coarsening-upward intervals of strata (highstand deposits above maximum flooding surfaces). Using these criteria, both 3rd- and 4th-order sequences have been identified. An idealized 4th-order sequence consists of deeply incised, fluvial channel sandstone separated from overlying tidally modified estuarine sandstone and mudrock by a ravinement bed, and capped by coarsening-upward bayhead delta facies. The relative thickness of fluvial versus estuarine facies within a fourth-order sequence reflects a balance between accommodation and sediment supply within a 3rd-order relative sea level cycle. Lowermost 4th-order sequences are dominated by fluvial facies, whereas the uppermost sequences are dominated by estuarine facies. Therefore, 3rd-order sequence boundaries are interpreted to lie at the bases of the lowermost, fluvial-dominated fourth-order sequences. Coarsening-upward intervals that record the maximum landward extent of marine conditions are interpreted as highstand deposits of the composite third order sequence. Thus, the NRF consists of thick, superimposed fluvial sandstone of the lowstand systems tracts and anomalously thin transgressive and highstand systems tracts. Asymmetrical subsidence within the foreland basin resulted in westward amalgamation of multiple, 4th-order, fluvial valley-fill successions and sequence boundaries. The Early Pennsylvanian time period was characterized by global icehouse conditions and the tectonic assembly of Pangea. These events affected the geometry of the overall stratigraphic package, which can be attributed to high-magnitude, high-frequency, glacioeustatic sea-level fluctuations superimposed on asymmetric tectonic subsidence. / Master of Science

The brook trout <i>Salvelinus fontinalis</i> is the only salmonid native to the southern Appalachian Mountains, and is distributed across eastern North America from Canada to Georgia. This species was once abundant in coldwater lakes and streams throughout its range, but environmental disturbances and the introduction of non-native species have drastically reduced the number and sizes of wild populations. Genetic evidence suggests a division at the subspecies level between southern- and northern-derived brook trout populations, with the break between the two forms occurring roughly at the New River watershed. Before the subspecies structure was recognized, brook trout of northern origin were widely stocked throughout the Southeast. The primary objective of this study was to determine the phylogenetic origin of all wild brook trout populations in southwestern Virginia using allozyme markers. Seventy-eight streams believed to contain brook trout in the New, James, Holston, and Yadkin river drainages were sampled by backpack electrofishing. Muscle tissue samples were collected from 916 individuals from 56 populations using a non-lethal biopsy technique. The samples were analyzed by cellulose acetate gel electrophoresis and histochemical staining techniques. Variation at four polymorphic loci, including the diagnostic creatine kinase (<i>CK-A2*</i>) locus, was quantified in terms of genetic diversity and population genetic differentiation. Allele frequencies indicated that 19 populations were of putative southern origin, 5 of northern origin, and 32 of mixed genetic origin. The secondary objective was to determine the geographic distribution of southern- and northern-form brook trout populations throughout the native range using data compiled from all known genetic studies. A map of these data showed that the break between the southern and northern form is sharp, occurring at the New/Roanoke-James watershed divide. Populations from the New River drainage expressed the southern allele at a frequency of 85%, suggesting that their historic native character is southern, and that the presence of northern alleles is due to stocking or stream-capture events. The persistence of the southern form, despite the heavy stocking of northern-derived individuals, may be evidence of an adaptive advantage for the southern form of the species. Existence of adaptive genetic differentiation supports the case for conservation of the southern form of the species in future management of brook trout. / Master of Science

A series of geologically recent faults was discovered within a folded succession of stratified alluvial sediments, commonly referred to as New River terrace deposits, near the town of Pembroke in Giles County, southwest Virginia. Geological and geophysical investigations were utilized to characterize the terrace deposits and investigate the nature of the observed faults. Geologic mapping of the underlying carbonate bedrock provided orientation measurements of fault, bedding, and joint planes; however, none of the features mapped within the bedrock could be directly correlated with the observed faults. The results of geophysical studies suggest significant variations in lithology within the alluvial sediments. Seismic velocities (P-wave) obtained from reversed seismic refraction profiles range from 900-1700 meters/second, while apparent electrical resistivity values vary from 300-2000 ohm-meters. A 75 meter wide, east-west trending low resistivity zone extending across the center of the study area is juxtaposed against an extremely high resistivity zone which is present to the north. The results of seismic reflection and electrical resistivity data analysis are interpreted to suggest that several small and large scale extensional faults may exist throughout the sediments, possibly reaching depths of up to 30 meters. An isopach map of preserved terrace thickness indicates that the faults lie within an east-west trending zone of maximum terrace thickness (35-40 meters thick), which corresponds to a topographic rise in land surface. A structure contour map of the bedrock surface reveals an area of lowest bedrock elevation beneath this zone, implying inverted topography. Results indicate that the evolution of the terrace might be related to ongoing karst processes within the bedrock. / Master of Science

The effects of Bacillus thuringiensis var. israelensis (Bti) on chironomid production was assessed in the New River in southern West Virginia. Production was measured in a year without Bti treatment (1987) and a year with treatment (1988). Sampling was conducted from June through November at Sandstone Falls, 16 km below Bluestone Dam in Summers County. Sampling was restricted to rock outcrops covered with Podostemum (river weed). Samples were collected at 2- wk intervals with a quantitative device that delineates an area of 0.01 m². Three species belonging to two genera accounted for about two-thirds of chironomid production in both years. Cohort production intervals were estimated to be 27 d for both species of Cricotopus and 20 d for P. convictum. Total chironomid production from June through November 1987 was 10.8 g/m² and during the same period in 1988 was 33.8 g/m². In 1987, the production of C. bicinctus and Cc. politus was 4.09 g/m² (38% of total chironomid production), and production of P. convictum was 2.46 g/m² (23%). In 1988, the production of C. bicinctus and C. politus was 12.39 g/m² (37%), and production of P. convictum was 11.38 g/m² (34%). Bti treatments caused no adverse effect on chironomid production in 1988, because the same species were dominant and their production was 3X higher. In addition, density and mean individual biomass were greater in 1988 than in 1987. The production increase in 1988 was probably related to environmental factors other than Bti treatments, such as discharge and Podostemum standing stock. / Master of Science

Much of the bedrock surface of the Southern Appalachian Valley and Ridge Province is covered by a veneer of surficiaI deposits classified as alluvium, colluvium, and residuum. In this investigation the surficial geology of a 60-km² area of the New River drainage system was mapped at a scale of 1:24,000. The area is located within the Eggleston and Newport 7 1/2-minute topographic quadrangles in Giles County, southwest Virginia. The data derived from mapping the surficial geology (particularly alluvial deposits), in conjunction with other field observations and with heavy-mineral analyses, are interpreted in terms of provenance, depositional environment (or accumulation), and preservation of the surficial deposits. In addition, these data are applied to an interpretation of the evolution of the New River drainage in the Valley and Ridge Province during the latter half of the Neogene. The areal distribution of the surficial materials indicates that in a humid, temperate climate deposits of surficial materials tend to be preserved if they overlie carbonate bedrock which weathers chemically but tend to be eroded from shale and sandstone bedrock which weathers mechanically. In carbonate terrains where surface runoff is minimal, surficial materials are let down in place by solution and have been accumulating in a piecemeal fashion over a time period which in some areas may include all of Cenozoic time. Analysis of the transparent heavy-mineral assemblages contained in the modern alluvium and older alluvial deposits of the area indicates that radiation-damaged zircon (intermediate and metamict) is unstable under conditions of subaerial weathering. Earlier workers have suggested that zircon is dissolved by acid ground water. This study supports these earlier suggestions and further demonstrates in a semiquantitative manner that the solution rate of radiation-damaged zircon may be a linear function of time as measured against either tourmaline er normal zircon. The estimated period of time over which the solution rate of zircon appears . to be lil1ear is on the order of 10 m.y. The areal distribution and lithology of alluvial deposits provide evidence which can be used to reconstruct the late Cenozoic evolution of part of the New River drainage system within the Valley and Ridge Province. These data, in conjunction with assumptions involving lithologic and structural variations within the stratigraphic section which has been removed by erosion, suggest that the James and Roanoke Rivers have captured three northeastern tributaries of the New River during the latter half of the Neogene. Within this time period no evidence was found of major changes in the course of the New River itself (except for meander loops) between Radford and Narrows. / Ed. D.

This theses compares the benefits of energy self reliance strategies with the benefits of industrial development strategies to determine which strategies create greater benefits as a method of economic development. A critical factor, which is examined, is the probability of success for industrial development strategies as opposed to the near certain benefits from the self-reliance strategies. The methodology employs a Virginia input-output model using a regional purchase coefficient technique to regionalize the model for the New River Valley Region of Virginia. The strategies are developed based on two distinct expenditure levels, acting as resource constraints on the strategy selection, in order to compare the return on additional expenditures. / Master of Science

Two species of black bass, smallmouth bass Micropterus dolomieu and spotted bass Micropterus punctulatus, are sympatric in both riverine and impounded sections of the New River, Virginia. Resource use (habitat and diet) by the two species was investigated to determine patterns and extent of resource partitioning between them and how those patterns might differ between lotic and lentic environments. Individual fitness indicators (i.e., growth and body condition factor) were also measured to assess performance of populations of the two species in the study areas. Fitness indicators suggested relatively good performance of both species in both river and impoundment, which implied that competitive pressures were not intense. Diet analyses indicated fairly high overlap in prey types consumed. High fitness combined with considerable diet overlap suggested that food availability was adequate, and that segregation in this impounded river system was not on a trophic basis. The two species were found to segregate spatially, with spotted bass predominant in the impoundment and smallmouth more abundant in the river. Spatial segregation was also apparent within both river and impoundment habitat types. / Master of Science

The influence of physical parameters on spawning times of smallmouth bass and subsequent growth of young-of-the year was studied via the otolith aqeinq technique. Daily rings on the saqittae of young-of-the-year smallmouth bass were first formed the day of swim-up, and continued to be formed until growth was significantly reduced in the fall. Daily age estimates of young-of-the-year smallmouth bass collected from one unregulated section of the New River, two regulated sections of the New River, and two tributary streams of the New River were used to back-calculate spawning dates. Growth rates of young-of-the-year declined as fish got older. Smallmouth bass spawned early in the spawning season did not initially grow as rapidly as those spawned later. Spawning occurred from late-April through mid-July, 1982, at mean daily water temperatures ranging from 12.5 to 23.5 C. Frequency distributions of spawning dates were nearly identical among study sites, as were hydrological events. A major flood in June separated the spawning season at all study sites into t)lo distinct periods. Discriminant functions were developed from four water temperature variables that differentiated between daily stream conditions prior to the spawning season and daily stream conditions during the spawning season. Mean daily water temperature was the most important of the four variables in differentiating between groups of conditions. / Master of Science

Density estimates of the species and life stages in different habitat types were made from electrofishing collections and underwater fish counts. During midday, fish densities in edge pool and riffle habitats were comparable, but densities in edge pool habitat were significantly higher than densities in middle pool and run habitats. Snag and edge riffie habitats supported the highest densities of fish. Habitat use and activity shifts between daytime and nighttime were found for many species. Fish species and lifestage composition and densities differed among the habitat types, and five habitat-use guilds (edge-pool, middle-pool, edge-channel, riffie, and generalists) were described. Larger centrarchids preferred deep habitats with slow velocities (deep edge and middle pool, and snags), while young centrarchids preferred shallower habitat. However, all sizes of smallmouth bass were nearly ubiquitous in the habitats of the study area. The cyprinids and percis preferred shallow areas, but preferences for velocity differed among the species and lifestages. Spawning and habitat preferences of the endemic bigmouth chub, Nocomis platyrhynchus, were described. Bigmouth chubs used areas with plenty of small to large gravel (3-64 mm diameter), shallow depths, and moderate velocities for constructing spawning mounds. Bigmouth chubs were seen only using riffie and adjacent run habitat during late summer. Within these areas, depth, velocity, substrate, and cover were used in accordance with their availability, except for an avoidance of the shallowest available depths. Bigmouth chubs occupied positions near the substrate, where velocities were slower than the mean water column velocity. / M.S.