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Biostratigraphic study of the Late Silurian-Early Devonian strata of western Virginia reveals the presence of at least three potentially useful multielement conodont apparatuses. Two multielement species of the genus Ozarkodina may prove to be useful in determining the boundary between the Silurian and Devonian Systems in the Appalachian Basin. Currently, a single form species, Icriodus woschmidti woschmidti, which was found in the lowermost New Creek Limestone at Low Moor, Virginia, is used by previous agreement to denote the base of the Devonian system. In the absence of this standard paleontologic indicator, multielement species of the genus Ozarkodina aay be useful. Ozarkodina steinhornensis eosteinhornensis is identified from the Silurian Tonoloway Formation in the area of New Castle, Virginia. Ozarkodina steinhornensis remscheidensis, which is transitional to Oz. s. eosteinhornensis, has been identified in the overlying Late Silurian-Early Devonian Keyser Formation and Early Devonian New Creek Limestone near New Castle and Low Moor. Oz. s. remscheidensis, which is reported to occur first in the Gedinnian, has been suggested as a possible alternative indicator of lowest Devonian strata (Walliser, 1971). However, because of the transitional relationship of these two multielement species, abundant yields of conodonts are necessary to determine the first appearance of Oz. s. remscheidensis. Elements belonging to a third conodont apparatus, Delotaxis elegans, have been recovered from the Keyser and New Creek intervals at the same locations. Delotaxis elegans may ultimately prove to be a significant biostratigraphic marker with further study of these units. An overview of the Late Silurian-Early Devonian strata in Alleghany, Botetourt, Craig, and Roanoke Counties is developed to provide a regional perspective of this stratigraphic package and to illustrate significant biostratigraphic markers. Unconformities, wedge-outs, facies changes, and thickness variations are examined within the study area based on nine measured sections and a review of pertinent literature. Clastic units and quartzose carbonates within the Helderberg Group are discussed with regard to source area. / Master of Science

Call number: LD2668 .T4 1965 L77 / Master of Science

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 189-215. Also available online.

Trilobites collected during the past twenty years from the Morgan Creek, Point Peak, and San Saba members of the Wilberns Formation constitute the material basis for this paleontologic and statistical investigation. Eighty-nine species assigned to forty-five genera belong to zones of the upper Franconian and Trempealeauan Stages of the Upper Cambrian Croixan Series. New zonal names are proposed in the interest of a regionally applicable nomenclature. Although none of the zonal nomenclature is identical to that of the Cambrian Correlation Chart, the four zones recognized in central Texas are equivalent to the eight highest zones of the Chart. Stratigraphically lowest is the Franconian Taenicephalus zone, with a locally recognized Parabolinoides subzone at its base; this is equivalent to the Conaspis zone of the Correlation Chart. The Franconian Idahoia zone, with a locally recognized Idahoia lirae subzone at its base, is equivalent to the Ptychaspis subzone of the Ptychaspis-Prosaukia zone of the Correlation Chart. The sparsely fossiliferous Ellipsocephaloides zone corresponds to the Prosaukia subzone of the Ptychaspis-Prosaukia zone of the Chart. Almost two-thirds of the trilobite species occur in the Trempealeauan Saukia zone, which corresponds to the five highest zones of the Correlation Chart; local subzones, in ascending order, are the Saukiella pyrene subzone, the Saukiella junia subzone, the Saukiella serotina subzone, and the Corbinia apopsis subzone. The succession of ptychoparioid trilobite faunas contained within these zones make up the Ptychaspid biomere. The base of the biomere is at the base of the Taenicephalus zone; the top coincides with the lowest occurrence of the Ordovician trilobite fauna. Trilobite families that characterize the Ptychaspid biomere are the Ptychaspididae and the Parabolinoididae. Regression analyses of range data for all Saukia-zone taxa were used to compile a quantitative range chart. Differences between the quantitative chart and my intuitive range chart were not significant. Systematic descriptions include new species of Conaspis, Idiomesus, Euptychaspis, Keithiella, Saukiella, Prosaukia, Calvinella, and Westonaspis?; and one new variety of Orygmaspis. / text

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Thesis (Ph. D.)--University of Adelaide, Dept. of Geology and Mineralogy, 1983. / Twenty four folded leaves of ill. in pocket inside the back cover of v. 2. Includes bibliographical references (leaves 146-164 (v. 1)).