Previously known only from the subsurface, the Piney Point Formation was recently discovered in outcrop along the Pamunkey River on the Virginia Coastal Plain (Ward, in ms.). The ostracode fauna of this unit is diverse and well preserved, and is here identified and described for the first time. It is composed of forty-five species of Ostracoda, twelve having been described previously, eleven having affinities to previously described species, and eight described as new. Based on correlation of the previously described species with ostracode faunas from the Gulf Coastal Plain, the age of the Piney Point Formation is middle Claibornian to middle Jacksonian, or middle middle Eocene to middle late Eocene. This shows that the Piney Point Formation is time-transgressive, because the ostracodes from the type locality are strictly middle Claibornian (Brown et al., 1972). The ostracode assemblage of the Piney Point is typical of one inhabiting warm, clear, open marine waters with a slow sedimentation rate and little reworking. / Master of Science

Large amplitude seismic reflections from within the Catoctin Formation of central Virginia are interpreted to originate from acoustically thin beds of interlayered metabasalts and metasediments. Large acoustic impedance contrasts exist between epidotised layers ( epidosites and volcanic breccia) and non-epidotised layers (greenstones and phyllites) within the Catoctin Formation. Acoustic impedance contrasts also exist between greenstones (metabasalts) and phyllites (metasediments). Constructive interference of small amplitude reflections from thin beds result in large amplitude, reverberating reflections. Thin bed reflections that approximate the first derivative of the source wavelet constructively interfere to give even larger amplitude reflections than those originating by conventional tuning. Computer modeling based on two geologic sections of thin beds of epidosites interlayered with greenstones and of greenstones interlayered with phyllites and epidosites indicates that large amplitude reflections result from constructive interference of thin bed reflections. / Master of Science

The East River Mountain district. located in Tazewell and Bland counties. Virginia. is an area of approximately 80 square miles much of which is underlain by ferruginous sandstones of Clinton age. The extensive areas of outcrop of the ferruginous sandstone make large tonnages of the rock readily available for open-pit quarrying. Investigations show that within the area studied over 60 million tons of hematite were contained in the ferruginous sandstones present in the East River Mountain district. Thus these sandstones constitute a large potential for commercial iron ore if extraction is possible. In September of 1956 9 laboratory study of the ironbearing sandstones was inaugurated primarily to discover a commercially feasible method of beneficiating and concentrating the hematite contained in the sandstones. High-tension electrostatic, wet and dry magnetic. and ultrasonic methods of extraction were studied. Of these methods ultrasonic insonation of the ferruginous sandstone appears to hold the most promise for obtaining satisfactory concentrates of hematite from the sandstone. A marked upgrading of the hematite content was noted after the crushed iron-bearing sandstones were subjected to ultrasonic insonation at a frequency of 22 kilocycles. The ultrasonic treatment used to concentrate the hematite appears to be both adaptable and economical on a commercial scale. / Master of Science

The McMullin syncline is located in Smyth County within the Valley and Ridge Province of southwestern Virginia. The syncline lies in a recess along the northern periphery of the Seven Springs-Pulaski thrust and consists of seven small fault blocks which are complicated by three generations of folding, the the F2 and F3 folds trending oblique to nearly perpendicular to regional Appalachian trends. Two components of stress operated on the local area, a major one directed from the southeast and a lesser one from the southwest. The latter component resulted from rotation of the Seven Springs-Pulaski thrust. The Marion, Virginia area where the McMullin syncline occurs developed up-plunge from the Tennessee basin depocenter. The McMullin syncline includes the Middle Ordovician cartonate onlap package which was deposited over the lower Ordovician upper Knox Group during a major transgression. Altogether, 3519 conodonts representing 48 monoelement or multielement apparatuses and 19 form species were recovered. Biostratigraphically important conodonts recovered from this ramp to basin sequence include: Polyplacognathus friendsvillensis, Polyplacognathus sweeti, Eoplacognatus lindstroemi, Pygodus serrus, and Pygodus anserinus. The Polyplacognathus friendsvillensis-P. Sweeti evolutionary lineage is a valuable datum on which to base correlations in the Southern Appalachians. The datum in this study confirms that the transgression moved northwestward. The Lenoir and Arline Formations correlate with the Pygodus serrus Zone of Eergström’s (1971a) North Atlantic zonation and the Effna Formation with the lowermost Pygodus anserinus Zone. / Master of Science

The Fries fault zone south of Riner, Virginia is marked by a ductile, greenschist-facies thrust that places Middle Proterozoic gneiss over deformed Late Proterozoic(?)—Early Paleozoic rocks of the western Blue Ridge province. This work presents an analysis of the field relationships and finite strain patterns within the fault zone, and further relates these features to an interpretation of its structural framework. A geologic map of the fault zone is provided, in addition to more detailed lithologic descriptions within the text. Noteworthy aspects of the field geology include: (1) the discovery of a reasonable protolith to the mylonitic Little River Gneiss, which could previously only be inferred; and (2) the recognition of a varied lithologic assemblage that is considered to be correlative with the Pilot Gneiss, which is exposed along strike within the Brush Creek anticlinorium. Kinematic analysis of tectonic fabrics within the Little River Gneiss, Pilot Gneiss, and Chilhowee Group suggest that the fault zone developed in response to southeast—northwest shortening, accommodated by general noncoaxial flow, which produced a top-to-the-northwest sense of shear at all scales of observation. However, it is evident that the original stratigraphic anisotropy within the Chilhowee Group effectively partitioned the coaxial and noncoaxial components of strain. Additional finite strain analyses within the Chilhowee Group, including the correlation of R_f/Ø data with quartz c-axis fabrics, indicate that there is considerable variation in the geometry of finite strain along the fault zone. Whereas flattening strains appear to predominate, it is evident that domains of constructional strain and plane strain are localized near the nose of the Brush Creek anticlinorium. These data are considered to support an interpretation in which the Pilot Gneiss and Chilhowee Group were metamorphosed and folded into a doubly-plunging antiform during the Taconic orogeny (ca. 480-435 Ma), and that progressive shortening of the Laurentian continental margin during this interval caused the Little River Gneiss to be uplifted along the Fries fault. The present structural framework of the Fries fault zone south of Riner, Virginia is thus considered to represent a northwest-vergent fold composed of Late Proterozoic—early Paleozoic strata, which is transected by the base of the Little River Gneiss. / Master of Science

Attempts to recover reserves of coal situated within barrier pillars in the Beatrice Mine using the room and pillar method have thus far been largely frustrated due to magnitude, in or near the working places shortly after commencement of retreat mining in a given area. Since pillar mining offers the opportunity for achieving relatively high production at a low cost per ton the development of methods for the detection and distressing of areas of high bump probability in advance of mining would significantly improve the competitive position of the deep mines operating in the Pocahontas No. 3 seam in Buchanan County, Virginia. Unstable ground movements occurring within a panel of pillars removed using continuous mining equipment were detected using the microseismic monitoring system developed by the U. S. Bureau of Mines. Areas of high stress occurring within the panel were detected by a series of convergence points installed by the mine operator and by small diameter auger holes drilled into individual pillars. The highest levels of seismic activity were recorded during the mining of pillars which, though themselves suffering convergence to some extent, were situated inby areas in which greater amounts of closure had occurred. The presence of anomalous geologic structures in the roof strata outby, as well as the presence of pillars of irregular geometry, in close proximity to areas of high seismic occurrence was also noted. Of the pillars probed using auger drilling it was determined, using criteria developed in Poland for evaluation of bump prone pillars, that two pillars in the next panel to be mined presented an extreme hazard, while several others were of intermediate hazard potential. The practice of injecting water into pillars through holes drilled well in advance of mining was found to be largely ineffective, though injection carried out immediately following drilling of the hole in a highly stressed pillar did induce rapid convergence for a period of approximately two weeks. / M. S.

The geology of Frederick County, Virginia is known mostly from surface mapping. Based on this work are interpretations of the subsurface geology including cross sections which have been constrained by the surface geology and by the method of area balancing based upon palinspastic reconstruction. With the intent to further constrain these cross sections. gravity measurements were made at 422 sites in Frederick County. Then, gravity anomalies were compared with theoretical gravity profiles calculated from two dimensional models of density distribution based upon the cross sections. Using the cross section geometry and densities published for the known and inferred rock units, the theoretical gravity profiles did not compare favorably with corresponding Bouguer gravity profiles. However, by modifying the geometry of the model units and adjusting the model unit densities, a reasonable fit between theoretical and Bouguer gravity profiles was obtained. Although the geometrical modifications adhered to the structural style, no attempt was made to area balance these modifications within the model. / 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.

The Parsons Lineament (a major Appalachian Cross-strike Structural Discontinuity, CSD) extends from the Plateau of West Virginia into the Valley and Ridge Province in northern Rockingham County, Virginia. Regional and second—order folds change in strike from typical Central Appalachian trends (N30—35°E) to near due north within the CSD, regional anticlines plunge out, and major thrusts terminate within thisi zone. ln the Rockingham County portion of the Broadtop Synclinorium, the CSD is marked by an increase in intensity (ratio of surface area to volume) of systematic joints and second—order, sinistral strike-slip faults. Two sets of regional joints occur : J1, a pervasive east—west— trending, near vertical joint set, and J2 which varies with structural position. Peaks in J1 intensity coincide with known strike-slip faults and pronounced photolineaments. J2 is associated with closure on the Bergton anticline. Drilled depths to the Oréskany horizon, age relations and intensity of systematic joints suggest deformation associated with a northeast—facing lateral ramp is responsible for both the Parsons lineament and closure on the Bergton natural gas field. Within the North Mountain thrust sheet, the Parsons CSD consists of a linear zone of anomalously-trending, second-order folds and shears near the nose of the Linville anticline. Blind thrusts responsible for second-order folding are exposed in a quarry face and strain values (from pressure fringes adjacent to pyrite framboids in Martinsburg shales) suggest that the second-order folds adjacent to the Linville anticline are the result of movement on the Saumsville fault in the subsurface. Age relations of S1 and S2 cleavages and V2 calcite veins indicate an east-to-west order of thrusting for the Pulaski-Staunton and Saumsville faults. The linear disturbed zone results from displacement transfer at the termination of the Saumsville fault and, together with the structural anomalies in the Broadtop Synclinorium, constitutes the Valley and Ridge extension of the Parsons CSD. / Master of Science

Geologic mapping along the northeasternmost 25 miles of the St. Clair fault, which traverses the Central and Southern Appalachian juncture at about the middle of this segment, was accomplished to observe the changes in geologic style and structural trend that occur across the juncture in this northwesterly Valley and Ridge strike belt. The study area is an excellent smale scale area for observations on the nature of the juncture over the larger scale as it includes most of the features that characterize this juncture such as change of physiographic and structural trend and transition from thrust fault-dominated deformation to fold-dominated deformation. The juncture or recess is prominent in the study area as a sharp bend in Gap-Moss Mountains and is in fact one of the sharpest bends occurring at the junction. Southwest of this recess, the stratigraphic units on the northwest of the St. Clair fault are overturned and a broad syncline is formed on the northwest, known as the Hurricane Ridge. The axis of this fold closely parallels the strike of the St. Clair fault. As the junction is approached the Hurricane Ridge syncline changes axial strike to the north and passes northwest of the Browns Mountain anticlinorium which is plunging out into the junction. Just northeast of the recess the St. Clair fault bifurcates and its strike is slightly changed when the segments rejoin. Northeast of this point, the St. Clair fault loses stratigraphic displacement and instead of a single broad fold northwest of the fault and parallel to it, there are numerous small folds developed that strike 20-30° more northerly than the fault. The fault does not, however, truncate any of the folds. The St. Clair fault extends 13 miles into the Central Appalachians where it dies out down the plunge of an anticline at Morning Knob in Alleghany County, Virginia. A strong shear zone is evident in the core of the structure at Morning Knob but is lost as the competent Silurian units plunge under Devonian shales. Integrating this information with other recent work on the juncture it may be concluded that: 1. The change of topographic and structural trend across the Central and Southern Appalachian juncture does not require any significant difference in timing of deformation. 2. There is probably no significant difference in orientation of principal stress across the juncture but rather the change of trend and differences of geologic "style" reflect contrasts in thickness and facies within the sedimentary column and contrasts involving basement topography which indirectly influence cover structure. Thus the changes evident across the juncture are seen to be the result of differential physical response to the applied stress. / Master of Science