Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Lindgren. / Vita. / Bibliography: leaves 385-402. / Ph.D.

The eastern Blue Ridge near Warrenton is composed of low grade metamorphosed and very little deformed clastic sedimentary rocks, which unconfomably overlie Middle and Late Proterozoic gneisses and granites. A thick succession of Late Proterozoic metavo1canics (Catoctin Formation) lies above the metasediments. The metasediments in the Warrenton area are the Lynchburg and Fauquier Groups, the latter of which is raised herein from a formation to a group. The lowest unit, the Bunker Hill Formation, is dominated by coarse- to very coarse-grained feldspathic sandstone, typically trough and planar cross-bedded, with minor fine-grained sandstone and siltstone or granule conglomerate. The overlying Monumental Mills Formation is dominated by thin bedded fine sandstone and siltstone, with minor laminated mudstone towards the top. The next overlying unit, Ball Mountain Formation, is composed of thick beds of medium to coarse sandstone and rare conglomerate, interbedded in black schists and dark laminated mudstones. The facies observed and correlation with previous work farther south suggests that these three formations record a continuous transgressive alluvial to deep water rift sequence. The Ball Mountain passes northwards to the lower Swains Mountain Formation, which is dominated by massive sandstone, and farther north to the upper Swains Mountain and Carter Run Formation, a continuous fining upwards succession from medium sandstone to laminated mudstone. From south to north the clastic sequence shows an overall thinning, and at the time of eruption of the Catoctin volcanics probably was shoaling as well. The overlying Catoctin shows a basal volcanic breccia unit covered by a thick succession of lavas. Medium grained, parallel bedded feldspathic sandstone occurs as lenses along a regionally continuous belt in the upper part of the formation. Numerous metamorphosed mafic intrusives were observed within the clastic sequence, and evidence for Late Proterozoic faulting was documented. The whole assemblage of lithofacies is interpreted to represent a continuous rift sequence, and the presently exposed section was probably oblique to the trend of the original rift. The rift stratigraphy can be traced in all the Warrenton area. The whole sequence is characterized by one low grade progressive metamorphism. Deformation is minimal and took place in two stages: Development of pervasive foliation (S 1) in varying degrees throughout the sequence (event: Dl). Subsequent folding and faulting and development of a localized discrete cleavage (S2) (event: D2). The observed structural features can be correlated with features described by other workers in adjacent areas. The map-scale structure is dominated by a change in attitude of the strata from east-dipping next to the basement, to open folded and gently dipping farther east. Considering that the whole Blue Ridge is an allochthonus thrust sheet, this change probably corresponds to the eastern subsurface edge of the basement block, on which the rift sediments were deposited, above a gently dipping decolement. Some workers have proposed tectonic models of the central Appalachians in which accreted terrane boundaries, are present along the eastern Blue Ridge. The continuous rift stratigraphy and the tectonic evolution proposed herein do not support such models. / Master of Science

The Precambrian or Canbrian Unicoi Formation in southwestern Virginia consists of at least three litho logically distinct rock sequences which can be distinguished as formations. The Uhicoi therefore should be raised to the rank of group. The lowest rock sequence is named Iron Mountain Formation; the middle sequence, consisting of three basalt flow and inter-layered claatic sedimentary rocks, an the upper sequence of clastic sedimentary rocks are not named. / Ph. D.

Many coal mines in southwestern Virginia and West Virginia are plagued with excessive deterioration of roof shales. Shale flakes and sheets spall off the roofs at unpredictable intervals and create hazards in many coal mines (P1.1). The failures are more frequent during the summer months when the incoming air is at a higher temperature than the roofs and walls of the mine. This differences in temperature causes the moisture of the air to condense on the cooler parts of the mine. Prof. C.T. Holland, Department of Mining Engineering, Virginia Polytechnic Institute, has suggested that this type of roof failure may depend upon some mineralogical or chemical change caused by the increase in moisture on the rooms of the mine. In addition to the weathering process, some roof shales are notoriously susceptible to failure in those places where ground-water seepage is prevalent. The failures caused by this type of situation at the entry of a mine are usually more predictable than those caused by weathering. The purpose of this investigation was to determine if there were any significant differences in the mineral, chemical, or textural compositions of roof rocks which have failed and those which have not. / Master of Science

Graduation date: 2006 / Best scan available. Ink on original is smeared.

Before the arrival of Euro-Americans, the inland Pacific Northwest was settled by native people whose frequent intentional burning of the landscape promoted open stands dominated by large fire-resistant ponderosa pine. Fire suppression for nearly a century, livestock grazing, and logging of the largest trees has resulted in forests characterized by increased densities of small trees with closed canopies and unusually high fuel loads. Such structural changes to the forest ecosystem are particularly evident in the Blue Mountains of Oregon and Washington where forest managers are applying prescribed fire and thinning to reduce the risk of stand-replacing wildfire and reestablish stand structure characteristics seen prior to Euro-American settlement. Aboveground ecosystem recovery after disturbance is directly linked to the survival of ectomycorrhizal fungi (EMF) that form an obligate symbiosis with roots of tree species in the Pinaceae. EMF are critical for the uptake of nutrients by the tree host. The research comprising this dissertation explores the response of the EMF community structure and composition, live fine root biomass, and duff (decaying material) levels to (i) seasonal burning (fall vs. spring) and (ii) alternative fuel reducing restoration treatments (thinned only, prescribed burned only, thinned and prescribed burned). In both studies, treatments significantly reducing duff depth (e.g. fall burning and both restoration burning treatments) negatively impacted EMF species richness and live fine root biomass. The EMF community is characterized by a large number of species scattered at low frequencies across the sites. The frequent occurrence of a few species (e.g. Rhizopogon salebrosus and Wilcoxina rehmii), in both studies before and after treatment applications, demonstrates that some EMF species survive or rapidly reestablish after disturbance. The initial reduction of EMF species richness, fine root biomass, and duff levels after prescribed fire has important implications for whether managers can achieve the desired future condition of stands with large-tree retention and low fuel loads. The impacts of prescribed fire on the soil microbial community, along with the recovery potential of a site and the impending risk of stand-replacing wildfire in stands differing in structure from historic conditions, bear consideration when developing restoration prescriptions. / Graduation date: 2005

No description available.

A moderately intense, broadcast, understory, prescribed burn in 3 previously unburned ponderosa pine stands in southeastern Arizona felled or consumed 50% of all ponderosa pine snags ≥ 15 cm dbh. Large moderately decayed snags were most susceptible to burning. Large snags in the early stages of decay were preferred as nest sites by cavity-nesting birds. Numbers of live woody plants were reduced by 40%, mortality was greatest among shrubs and small trees. Canopy volume was reduced by 19%, the greatest impact was below 5 m. No species of cavity-nesting birds, or birds that associated with understory vegetation disappeared in the first season after burning, but 3 species decreased, and 1 species increased in abundance. The minor impacts of a single treatment with broadcast understory burning on bird populations will be ephemeral, but a repeated burns could have greater, and more lasting effects on the avian community.

Recent research has emphasized the importance of understanding the consequences of species loss, not just for biodiversity per se, but also for ecosystem resilience and functioning. Firstly, a baseline analysis of the effects of a naturally patchy landscape on avian community composition and resilience in a high altitude Afrotemperate forest landscape in South Africa is presented. Bird data from a point count survey of 706 counts at 31 forest sites was used to test whether taxonomic species diversity, functional species richness and density of birds provide insight into community resilience in this historically patchy ecosystem. Bird species richness of forest patches ranged from 17 to 38, with a total species richness of 50. Density was slightly but negatively related to both area and species richness. That density compensation is occurring in these Afrotemperate forests suggests a level of resilience in this system. Following on from this, cumulative species-area and function-area graphs were derived to quantify the loss of forest area or taxonomic bird species richness that this landscape may potentially sustain before ecosystem functioning is negatively affected. The concept that species’ patterns of distribution, abundance and coexistence are the result of local ecological processes has recently been challenged by evidence that regionalscale processes are equally instrumental in shaping local community composition. The historically and naturally fragmented Afrotemperate forests of the uKhahlamba– Drakensberg Park, South Africa, offer an interesting test case. In this study the relative effects of local and regional-scale processes on species assemblages in a naturally patchy forest system were investigated. By employing species-area and species-isolation relationships, and nested subset analyses, we showed that isolation (regional-scale process) had a greater effect on bird species richness and composition than area (local-scale process), though the species-area relationship was significant. Using generalized linear models and an information-theoretic approach to model selection, patch area, the size of the regional species pool as well as the distance to the nearest Eastern Mistbelt forest were all influential in determining local bird species richness in these montane forests. Thus, localities are regionally enriched within the constraints on species occupancy provided by the available habitat. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Using a genealogy of the narratives of the Guadalupes, I explore three moral identities. The Mescalero Apache exist as caretakers of sacred space. Spanish and Anglo settlers exist as conquerors of a hostile land. The park service exists as captives, imprisoned in the belief that economic justifications can protect the intrinsic value of wilderness. The narrative shift from oral to abstract text-based culture entails a shift from intrinsic to instrumental valuation. I conclude that interpretation of narratives, such as those of the Guadalupes, is not by itself a sufficient condition for change. Interpretation is, however, a necessary condition for expanding the cultural conversation beyond merely instrumental justifications to include caring for wilderness's intrinsic values.