The Bouguer gravity field, deterrmined from 395 measurements in Giles County, Virginia exhibits a broad positive anomaly approximately 12 mgal in amplitude situated over the Bane Dome, and several smaller anomalies of a few milligals amplitude. For the most part they are produced by the distribution of relatively high density carbonate rocks and lower density clastic rocks within the dome. These anomalies can be explained by two contrasting interpretations of the structure of the Bane Dome. One interpretation, represented by the geologic cross sections of Woodward and Gray (Woodward, 1985) and Bartholomew (personal communications, 1987) suggests that the dome is cored by a relative abundance of high density carbonate rocks transported by overthrusting within the Narrows thrust sheet. Because the gravity anomalies can be entirely explained by sources confined to the Narrows thrust sheet, this interpolation precludes the existence of significant lateral density contrasts associated with deeper structure beneath the decollement zone in the Rome Formation. The contrasting interpretation represented by the cross section of Gresko (1985), suggests a smaller proportion of carbonate rocks in the core of the dome due to duplex structures in the lower density clastic rocks. This interpretation proposes high angle faults with associated lateral density contrasts in the deeper rocks underlying the decollement. Because sources within the Narrows thrust sheet are insufficient to completely account for the gravity anomalies, the density contrasts associated with deeper structure are required. The Bouguer gravity field can be separated into regional and residual parts. The regional field is caused by changes in crustal thickness known independently from the seismic measurements of James, Smith, and Steinhart (1968). The remaining residual field can be explained in terms of anomaly sources within the upper 10 km of the crust. / Master of Science

Slope stability maps are useful in seismic hazard evaluation, land use and emergency planning, and geomorphological studies. Such maps were generated for Giles County, Virginia (approximately 1000 square km) by the synthesis of data sets for topographic slope, surficial deposits, geologic structure, and seismic slope response. Both graphical and digital techniques were used to generate a topographic slope map. Relevant limiting slope angles according to seismic shaking and land movement studies are <15, 15-35, and >35 degrees. These slope categories were integrated with geologic factors (presence/absence of colluvium; dip direction of bedrock) to develop a set of 12 slope stability categories tailored to the Appalachian Valley and Ridge geologic/topographic province. The techniques developed are directly applicable anywhere in the Appalachian Valley and Ridge province and can be adapted to other similar physiographic provinces. Both the slope map and the regional slope stability map can be produced graphically or digitally. The graphical method is inexpensive and fast when used to examine the detailed slope stability of a small area (7.5 minute quadrangle or less about 150 square km). The computer method but is more cost-efficient than the graphical method when studying the slope stability of larger areas. The location and type of slope movement triggered by seismic shaking, torrential rainfall, rapid snowmelt, or human activities can be estimated with the use of a regional slope stability map. Integration of the slope stability map with additional factors (such as joint pattern, seismic intensity attenuation pattern, or the local water table) results in a more detailed map for specific site studies. / M.S.

Master of Science

The purpose of this study was (1) to determine some of the problems in family foods and nutrition of dual-role mothers in Giles County, Virginia, and (2) to make recommendations of types of assistance homemaking teachers could render these mothers in solving some of their problems. Using schedule forms especially prepared for this study, information relating to problems in family foods and nutrition was personally collected from 32 mothers, and by mail from 32 mothers. None of the respondents had children who had reached the eighteenth birthday. Study of the data obtained on the schedule forms showed that the mothers who participated in this investigation were generally poor managers of time, energy, and available resources, had inadequate knowledge of nutrition, and failed to exercise desirable kitchen and shopping practices. The investigator recommends that homemaking teachers (1) emphasize experiences which lead to better use of time, energy, and available resources and (2) consider possible ways and means of promoting adult education programs which will meet the needs of the dual-role mothers. / Master of Science

M.S.

The Spruce Run Mountain area embraces about 45 square miles in the south-central portion of Giles County. It lies wholly within the Appalachian Valley and Ridge Province. The rocks exposed in the Spruce Run Mountain area range in age from Middle Cambrian to Lower Devonian. All the rocks are sedimentary rocks deposited in a marine environment and have an aggregate thickness of approximately 6,500 feet. An important disconformity separates rocks of Lower Ordovician age from those of Middle Ordovician age. The Saltville thrust, a southeast dipping thrust fault, crosses the Spruce Run Mountain area trending northeast. The thrust separates Middle Cambrian dolomite from Ordovician formations on the southeast flank of the Spruce Run Mountain syncline. The Spruce Run Mountain syncline is a northeast trending overturned syncline with a southeast dipping axial surface. The Clover Hollow anticline and the Bane anticline border the northwest flank of the Spruce Run Mountain syncline. The geomorphology and geologic history of the area are briefly discussed. / Master of Science

In the vicinity of Hoges Store, Giles County, Virginia, certain portions of the Five Oaks and Elway limestones containing more than 97 per cent calcium carbonate crop out near the event of the Thessalia anticline and John's Creek syncline and underlie an extensive area where dips probably are less than 20 degrees. Locally, part of the Benbolt, Gratton, and Witten are also high-calcium limestone. Sites for core drilling and possible subsequent mining or quarrying are inferred from study of exposed rocks, by chemical analyses of channel samples of selected zones of high-calcium limestones and by detailed geologic mapping. The report includes columnar sections showing the character and thickness of the limestone units. One large deposit of chemical-grade limestones was found about 1.5 miles northeast of Hoges Store, which is believed to underlie a large area wherein dips of the mineable strata are less than 15 degree. The amount of recoverable stone is estimated to be 80 million tons. Suggested locations for core drilling are shown. An anticline, two synclines and an intricate structure are the structural features of the area of study. The major structural features of Giles County are delineated on a sketch map. / Master of Science

[none] / 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 Poplar Hill area lies in the southwest corner of Giles County, Virginia and contains marine sedimentary rocks that range in age from Middle Cambrian to Middle Bilurian. The formations trend northeast in narrow outcrop belts. The summit of Walker Mountain is the southeastern boundary of the area and the southern slopes of Brushy and Buckeye Mountains form the northwestern boundary. Nineteen different rock formations are recognized and are mapped, measured, and described in detail. The geologic structure of the area is described and includes a major thrust fault, a homocline, two synclines, and two anticlines, all illustrated on the geologic map (P1. 1). The geologic history of the area is briefly discussed and several possible localities for limestone and dolomite quarries are described. / Master of Science