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Questions as to the tempo and mode of changes in faunal composition at the Triassic/Jurassic boundary remain unanswered. Inquiries are hampered by a general paucity of sections containing correlatable Late Triassic/Early Jurassic strata. Vertebrate fossil material from Cromhall Quarry, recovered as part of an extended project centered on Late Triassic fissure infillings in southwestern Britain, was organized into a biostratigraphic scheme in 1993. This scheme could prove important in correlating Late Triassic continental strata. The Cromhall data consists of taxonomic counts from individual Stratigraphic levels within a series of fissures. Level counts were sorted into a series of sequential sedimentary and faunal associations that rest on the assumption that significant differences in faunal composition occur between individual fissures, but do not exist between individual sedimentary strata within any one fissure. Before the biostratigraphic framework could be utilized, the actual degree of similarity between the fissure faunas had to be quantified and tested. The original database, and counts from newly processed material, were subjected to Principle Components and Cluster Analyses. The analyses suggest that the majority of stratigraphic levels within any one fissure contain faunas with very similar composition. Levels from fissures that are temporally sequential contain faunas that are somewhat similar in composition. Overlap, in faunas found in strata at the top and bottom of sequential fissures, can be detected. In addition, there is a trend toward increased presence of certain taxa in the younger levels. These results indicate that the biostratigraphic framework may be used to enhance Triassic-Jurassic boundary research. Master of Science

Early Ordovician Knox Group carbonates consist of meter-scale dolomite cycles deposited on a passive margin. The meter-scale cycles were deposited under warm, semi-arid conditions, under low amplitude sea level fluctuations on a relatively ice-free earth. The overlying Knox unconformity (~10 m.y. duration), formed by global eustatic sea level fall and tectonic uplift of the subducting margin at the onset of Taconic orogenesis. Middle Ordovician carbonates were deposited on a ramp peripheral to a foredeep in Tennessee. The Middle Ordovician High Bridge Group consists of a 2nd-order supersequence with three 3rd-order sequences (each 30 to 100 m thick), which record a long term change from humid conditions in TST's into more arid conditions during HST's. Peritidal cycles formed under low-amplitude eustatic fluctuations. The late Middle to Late Ordovician carbonates and clastics comprise a 2nd-order supersequence deposited on a ramp peripheral to the Taconic foredeep. The supersequence is composed of four 3rd-order sequences (each 40 to 80 m thick), which contain 11 parasequence sets (2 to 20 m thick). The small sequences are composed of stacked, predominantly subtidal meter-scale cycles (parasequences). Meter-scale subtidal cycles contain facies that suggest they formed under moderate amplitude (20 to 40 m) sea level fluctuations, likely produced by glacio-eustasy. However, peritidal cycles in the HST's indicate they formed under low-amplitude sea level fluctuations, thus suggesting the amplitude of sea level fluctuations decreased during 3rd-order sea level falls. The facies in the supersequence indicate they formed under cool, humid conditions during the 2nd-order TST and became more arid during the 2nd-order HST. The unconformity at the top of the supersequence formed during eustatic sea level drawdown associated with extensive Latest Ordovician glaciation. Ph. D.

Four intervals of Middle Pennsylvanian marine strata in the Breathitt Formation of eastern Kentucky, the Elkins Fork, Kendrick, Magoffin, and Stoney Fork, were measured, sampled for fossils, and described. Each marine interval was shown to be the product of a single episode of transgression and regression that led to the establishment of a variety of marine habitats in the central Appalachian basin. These habitats included marginal marine, nearshore normal marine, nearshore stressed, offshore normal marine, and offshore dysaerobic environments. Fossil collections were made and species abundance distributions were obtained for each paleontological sample. Multivariate statistical analyses such as cluster analysis and principle components analysis were used to classify fossil assemblages sampled into a variety of paleocommunity types, each associated with a particular lithological facies. Paleocommunity types that were found to occur in more than one of the four marine intervals were resampled at selected localities, with replicate samples taken at each locality. These additional samples were used to test for the presence of the same statistically defmed paleocommunity at different localities within the same marine units and to test for the recurrence of statistically defmed paleocommunities between marine units. Results of the analyses suggest that recurrence of similar fossil assemblages (paleocommunity types) is common in the Breathitt marine units whenever there is recurrence of comparable marine facies. However, recurrence of the same statistically defined paleocommunity is rare, with significant variation in the abundances of member species appearing each time a particular paleocommunity type recurs. This suggests that the recurrence of distinct fossil assemblages over intervals of geologic time can be explained by the repeated reinvasion of suitable habitats by the individual members of a persistent species pool, without recourse to ecological mechanisms needed for preserving or perpetuating particular community structures. Ph. D.

The Diligencia Formation comprises approximately 1600 meters of OligoMiocene continental siliciclastic sedimentary rocks and intercalated basaltic lavas, located in the eastern Orocopia Mountains of southeastern California. These deposits exhibit characteristics which may link them to tectonic processes diagnostic of both the Basin and Range physiographic province of North America, and the Transverse Ranges province of California. These different processes were active, however, during different periods in the history of the formation. The early Diligencia Basin had an asymmetric half-graben geometry, and formed in response to presently north-south directed extension along a listric detachment located along the northern basin margin. Facies associations determined from five measured sections through the lower Diligencia Formation reveal a distinctly asymmetric distribution of facies across the basin. The deposits along the northern margin of the basin are characterized by cobble and boulder conglomerates and very coarse-grained sandstones unconformably overlying marine sedimentary rocks of the Eocene Maniobra Formation. These sedimentary rocks represent a high-gradient alluvial fan system which developed against the steep escarpment of the listric detachment fault. These deposits contrast with those present along the southern basin margin. The sedimentary rocks on the southern margin are characterized by pebble and cobble breccias, pebble conglomerates, very coarse- to fine-grained sandstones and gypsiferous mudstones. These facies define a system of low-gradient alluvial fans/fluvial braidplain that were deposited on the relatively gently sloping hangingwall block of the detachment, and that interfingered with deposits of a playa lake complex that formed in the basin interior. The age of these deposits, basin geometry, and the style of sedimentation are very reminiscent of half-graben basins known from the Colorado River Extensional Corridor of the Basin and Range. Paleomagnetic studies indicate that the block containing the Diligencia Formation may have been rotated more than 90° about a vertical axis since deposition ceased. In addition, regional palinspastic reconstructions indicate that the basin may have been significantly further north and east in the Miocene. These observations suggest that the Diligencia Basin may be genetically related to similar basins in the western Basin and Range, and that Diligencia Formation can be better understood if viewed in this tectonic context. Sometime after deposition had ceased, the rocks of the Diligencia Formation were deformed under an imposed compressional stress field in association with activity along the Clemens Well Fault, a major, dextral wrench fault in the region. The action of the Clemens Well Fault also juxtaposed the Diligencia Basin with distinctive crystalline terranes of the central and western Orocopia Mountains, including the Mesozoic Orocopia Schist. The association of these rock types with structures characteristic of dextral strike-slip deformation have led most workers to tie the Orocopia Mountains to similar complexes in the Transverse Ranges province of southern California. In fact, the post-depositional history of the Diligencia Formation can best be understood only in the context of Transverse Ranges-style tectonic processes. The complicated history of the sedimentary and volcanic rocks of the Diligencia Formation has made it difficult for previous workers to sort out an appropriate tectonic context in which to describe them. Recent advances in our understanding of the sedimentary responses to Tertiary rifting in the western Basin and Range, provide a new opportunity to evaluate the history of these deposits and this work has determined that the Diligencia Formation has had close ties to both the Basin and Range and the Transverse Ranges at different times during its complex history. Master of Science

Marine organic-walled microplankton biostratigraphy of the Maastrichian Prairie Bluff Chalk is documented. A total of 69 dinoflagellate species were identified in the Prairie Bluff Chalk. Samples were studied from three sites in central and western Alabama (Tombigbee River, Millers Ferry, and Braggs). Also included were several samples of the overlying Clayton Formation, and the underlying Ripley Formation. The species and their stratigraphic ranges were compared with other coeval sections in the U. S. and Europe. Dinoflagellate Zones Va and Vb of Wilson (1974) are recognized in the Prairie Bluff Chalk. This suggests the age of the Prairie Bluff Chalk is restricted to late Maastrichtian. The Prairie Bluff Chalk correlates to the upper Providence Formation of Georgia (Firth 1984); the lower Providence being early Maastrichtian. The basal Clayton Formation may be latest Maastrichtian in age Master of Science

Sedimentological analyses, including detailed facies characterization and lateral profiling, demonstrate deposition in a bedload-dominated fluvial system for the quartzose sandstones of Lee Formation. Internal (architectural) elements of the sandstones consist primarily of truncated channel-fIll sequences. Individual channel elements, up to 20 meters thick, contain a complex hierarchy of bedform deposits. The principal internal component of channels were downstream-accreting (mid-channel?) macroforms; channel elements frequently contain deposits of more than one macroform. Reconstruction of the macroforms reveals accretion primarily by superposed bedforms that migrated down a low-angle front. Steeper, giant foresets, transitional along flow with the low-angle facies, indicate that the macroform episodically developed a steep slipface. Uppermost channels within the Rockcastle Member contain macroform elements with components of lateral accretion, interpreted as deposits of alternate bank-attached macroforms. Also recognized within channel-fill deposits are minor-channel, sandy-bedform, gravity-flow (attributed to bank slumping), and channel-bottom elements. The latter element is contained within a facies sequence that suggests rising- to flood- to waning-stage deposition. In general, deposition was probably during relatively high stage; little evidence of low-stage flow was recognized. Subordinate fine-grained facies are interpreted as levee and overbank deposits. Strongly unimodal paleocurrents, lack of facies that suggest low-stage reworking and paucity of lateral-accretion features indicate deposition in a single-channel, low-sinuousity, system (i.e., a low braiding index). Fluvial architecture similar to that found in the Lee Formation has been previously explained by deposition in multi-channel, braided-river systems. However, the internal architecture of sandstone members is also consistent with a single-channel origin. Individual channels were temporarily confined, during which time the passage of several macroforms aggraded the channel. Position of the channel in the alluvial plain was largely controlled by avulsion of the river from fully aggraded channel belts to other areas of the plain. Calculations reveal that avulsion of a single-channel system across a wide alluvial plain is a plausible mechanism for building the sheet-like sandstone bodies of the Lee Formation. Spatial arrangement of individual sandstone members of the Lee Formation was probably controlled by tectonic processes. Episodic thrust-loading in the orogenic belt to the east and subsequent flexure of the crust in the foreland basin caused a step-wise progression of the river system towards the west. Petrographic, sedimentologic and stratigraphic data indicate that source area and climate functioned as the primary controls on the mature composition of sandstones in the Lee Formation. Source areas were composed primarily of quartz-rich sedimentary rocks and were located chiefly to the northeast/north. A east/southeast source area supplied subordinate and low-grade metamorphic rock fragments. Intense weathering, associated with humid tropical climates, acted upon the detritus throughout the sedimentation cycle. Less important controls on composition were tectonics and transport/depositional processes that extended exposure of the sediments to the severe climatic conditions. Quartzose sandstones of the Lee Formation reflect lower rates of tectonic subsidence and greater recycling of sand-sized grains during transportation and temporary deposition on the alluvial plain, relative to lithic time equivalents to the east. Ph. D.

The Lower Mississippian Lodgepole/lower Madison Formations (20-225 m thick) developed along a broad (>700 km) stormdominated cratonic ramp. Three types of shallowing-upward cycles (5th order) are recognized across the ramp-to-basin transition. Peritidal cycles consist of very shallow subtidal facies overlain by algal-laminated tidal flat deposits, which are rarely capped by paleosol/breccia layers. Shallow subtidal cycles consist of stacked ooid grainstone shoal deposits or deeper subtidal facies overlain by ooid-skeletal grainstone caps. Deep subtidal cycles occur along the outer ramp and ramp-slope and consist of sub-storm wave base limestone-argillite, overlain by graded limestone, and are capped by storm-deposited skeletal-ooid grainstone. They pass downslope into rhythmically interbedded limestone and argillite with local deepwater mud mounds; no shallowing-upward cycles occur within the ramp-slope facies. Average cycle periods calculated along the outer ramp range from 30-110 k.y. The cycles likely formed in response to 5th order (20-100 k.y.) sea level oscillations. The cycles are stacked to form three 3rd to 4th order depositional sequences which are defined by regional transgressive-regressive facies trends. The ramp margin wedge (RMW) developed during long-term sea level fall lowstand conditions and consists of cyclic crinoidal bank and oolitic shoal facies which pass downdip into deep subtidal cycles. The transgressive systems tract (TST),which onlapped the ramp during long-term sea level rise, includes thick deep and shallow subtidal cycles; peritidal cycles are restricted to the inner ramp. The highstand systems tract (HST) developed during long-term sea level highstand and fall, and along the ramp is composed of early HST shallow subtidal cycles which are overlain by late HST peritidal cycles; shallow through deep subtidal cycles composed the HST along the ramp-slope. Ph. D.

An interbasinal study of Late Cambrian cyclic carbonate successions in the Appalachian and Cordilleran passive margins, the Texas cratonic embayment and the southern Oklahoma aulacogen has provided controls on the simultaneous development of peritidal to subtidal meter-scale cycles and the larger scale depositional sequences on which they are superimposed. Fining-upward peritidal cycles grade seaward into coarsening-upward, shallow to deep subtidal cycles that form a continuum across the carbonate platforms and are genetically linked to one another by shared lithofacies. Eustacy appears to exert the dominant control on the simultaneous development of peritidal and subtidal cycles on different carbonate platforms. Based on the recognition of dominant periodicities on power spectra derived from time series of subtidal cycles, high frequency eustatic oscillations may be controlled by Milankovitch astronomical rhythms. Interbasinal correlation of Late Cambrian depositional sequences was performed by graphic correlation and the time-equivalent intervals were correlated lithostratigraphically using isochronous biomere boundaries as time datums. Fischer plots of meter-scale cycles define changes in relative sea level based on the amount of extra accommodation space produced by eustacy beyond that provided by subsidence. Residual eustatic curves derived from subsidence analysis are useful for correlating the longer-term Late Cambrian sea level events and changes in the rate of sea level rise and fall can be used to define shorter-term events. Combining the sea level curves defined by Fischer plots and subsidence analysis with paleobathymetric curves of Late Cambrian cyclic strata suggests that the curves may approximate the form of the eustatic sea level curve. A composite "eustatic” sea level curve for the Late Cambrian was created by qualitatively combining the sea level curves defined by the different techniques for each of the four localities. “Eustatic" sea level curves defined by Fischer plots and subsidence analysis may be used to apply sequence stratigraphic concepts to onedimensional outcrop sections. Combined with systematic changes in the stacking patterns of meter-scale cycles, they can be used to define the internal composition of systems tracts, sequence boundaries, and flooding surfaces of third-order depositional sequences. One- and two-dimensional models of peritidal and subtidal cycle development indicate that peritidal cycle thickness is primarily controlled by accommodation space and deeper subtidal cycle thickness is primarily controlled by sedimentation rate. Whereas lithofacies within peritidal cycles alternate in response to fluctuations in sea level, subtidal cycle development may be related to fluctuations in fairweather and storm wave base that oscillate in harmony with sea level fluctuations. Ph. D.

The depositional and erosional history can be summarized as follows: 1) Subtidal carbonate shelf sedimentation through Early Ordovician (and including early Middle Ordovician White Rock?) time represented by the Beekmantown Formation. 2) Emergence of a Beekmantown terrain due to eustatic lowering of sea level and inception of gentle folding in late Early Ordovician (or early Middle Ordovician White Rock?) time. Subsequent erosion of the Beekmantown Formation and development of drainage and topographic relief. Development and filling of the paleodolinen on the topographic high. 3) Transgression of the sea. Previously developed drainage was drowned, evidenced by fining upward of the Cahoon Conglomerate Member into dolomite. Continued development and filling of the paleodolinen on the still exposed topographic high. 4) Development of tidal flats with numerous shoaling episodes as evidenced by fenestral fabrics and crystal silt in the New Market Limestone. Fresh meteoric waters available for crystal silt to fill voids throughout much of New Market time. Continued development and filling of the paleodolinen on the still exposed topographic high. Topographic high exposed until end of New Market time. 5) Beginning of Lincolnshire sedimentation marks complete submergence of topographic high. Deeper water, lower energy environment with abundant argillaceous material being brought into the basin and abundance of mud producing organisms. 6) Development of offshore biostromes as represented by Effna Limestone. Lack of mud may reflect high energy or the absence of mud-producing organisms. Master of Science

The Monmouth and Brightseat Formations contain a rich and diverse dinoflagellate assemblage. Thirty-five genera and sixty-six species, of which two genera and eight species are new, are described in this study. The stratigraphic distribution of the taxa is summarized in Figure 4. The content of the assemblage changes suddenly at the Cretaceous-Tertiary boundary with thirteen species making the~r first appearance at or just above the boundary. Nineteen species cross the boundary and thirty-five species are restricted to the Cretaceous. The rather sudden change in the nature of the dinoflagellate assemblage at the boundary is interpreted by the author to indicate a paraconformable relationship between the Cretaceous and Paleocene sediments. The term paraconformity is used since there is little field evidence (a few pebbles, some lignite, and evidence of boring) indicating any extensive period of erosion at the boundary. Master of Science

Geographical variation in taxa must be considered in evolutionary studies. The purpose of the present study is to demonstrate how geographical variation can be measured and documented for a taxon for one slice of time. Future evolutionary studies should document geographical variation for the entire geographical range of the species involved at several points of time throughout its total stratigraphic range. Thus the variation that is present at one time horizon may be separated from the variation that occurs through time. This work consists of a study of geographical variation in the genus Astarte (Phylum Mollusca: Class Bivalvia) from the Yorktown and Jackson Bluff Formations (early Pliocene) of the Atlantic Coastal Plain. Factor analysis, multivariate analysis of variance, and discriminant analysis were performed on measurements of specimens of Astarte from ten localities. There are significant differences in the morphologies of individuals among localities. These differences are due to the presence of different species of Astarte and to variation in size and external ornamentation within the same species. Seven species recognized from literature on Pliocene Astarte were identified among the individuals of the ten localities, but the statistical results indicate that these seven species may be grouped into three "types" that mayor may not represent species. The three types occur together in some localities, suggesting that they are distinct species living in sympatry. Factors influencing geographical variation include larval dispersal strategy and the effect of the environment. Master of Science

This study describes the biostratigrapaic distribution of Meramecian conodonts from three measured sections of the Greenbrier Limestone (Meramecian-Lower Chesterian), located in the Greendale and Hurricane Ridge Synclines of southwestern Virginia and southern West Virginia. The Little Valley Formation, Hillsdale Limestone and lower portions of the "Denmar-Gasper" and "Ste. Genevieve" Formations, consisting of rocks deposited in a variety of shallow carbonate-ramp environments, were investigated. Two new multielement conodont apparatuses were recognized: Kladognathus sp. A and Hindeognathus ("Apatognathus") laevipostica. Elements of Kladognathus sp. A are morphologically distinct from homologous elements of the K. levis-K. tenuis group. Evolutionary change from K. levis to K. tenuis is marked by slight Sa and Sb element changes, and the addition of an X element, DE Lambdagnathus fragilidens. Species of Kladognathus are promising Meramecian biostratigraphic markers. Also recognized in this study are species of: Cavusgqnathus, Gnathodus, Hindeodus, Idioprioniodus, Lochriea, Rhachistognathus, “Spathognathodus," Synprioniodina? and Taphrognathus. Meramecian formations in the study area can be correlated with the Mississippian stratotype (Illinois Basin) based on the following zones: Taphrognathus varians - "Apatognathus," "A." scalenus - Cavusgnathus aad Gnathodus bilineatus - Cavusgnathus charactus. Southward thickening of the "A." scalenus zone from the Hurricane Ridge Syncline (11 m) to the Greendale Syncline (180-200 m) reflects higher rates of sedimentation and subsidence in the depositional area of the latter. In addition, thinness of the zone in the Hurricane Ridge Syncline may be due to a hiatus between this zone and the younger G. bilineatus zone. This hiatus is not indicated by conodont faunas from the Greendale Syncline, which preserves a more complete Meramecian biostratigraphic record. Conodont and litahologic evidence for a coeval hiatus exists in other areas of eastern North America: the Illinois Basin stratotype, eastern Kentucky, Southern Ohio and eastern Tennessee. Master of Science

A detailed statistical study was performed on molluscan fossil assemblages collected from the Pliocene Morgarts Beach Member of the Yorktown Formation, located in Isle of Wight County, southeast Virginia. The principal objectives of this study were to examine potential sampling problems and biases inherent in paleontological research. This has been accomplished by statistically testing for the homogeneity, or lack thereof, in species assemblages obtained from samples collected from three localities within the Morgarts Beach Member. Multivariate analysis of variance, two-way analysis of variance, multiple comparison tests and cluster analysis were performed on data collected from a five horizon by five section sampling grid (18 feet [5.5 meters] high, 21 feet [6.4 meters] long) located at Morgarts Beach, Virginia. The results of this analysis demonstrate that the relative abundances of species present in the five horizons are significantly different, whereas the relative abundances of species present in the five sections are not significantly different. Results from cluster analysis show that species assemblages contained in samples collected from the Morgarts Beach Member located at Rushmere are substantially different from the Morgarts Beach type area assemblages, in terms of relative abundances of species. The reason for the lack of faunal similarity relates to the documented facies change between the two localities. The results demonstrate that there is no reliable method to obtain accurate census data (frequency abundance curves) from biostratigraphic or lithostratigraphic units deposited during anything but a restricted time interval. In addition, replicate sampling was found to be unnecessary when attempting to determine the relative abundances of species contained in closely spaced sections within the Morgarts Beach Member. Species accumulation curves were constructed from the data collected from the Morgarts Beach Member. Examination of these curves demonstrate that many rare species will not be found unless extensive collecting is undertaken. Master of Science

Condodont biostratigraphy has been established for complete sections of the Mifflintown, Wills Creek, and Tonoloway formations along the Wills Mountain anticline in the Central Appalachians. Beds in the Central Appalachians formerly called the Rochester Formation have been renamed the Cosner Gap Member of the Mifflintown Formation. The type section of the unit is at Cosner Gap, northwest of Maysville, Granty Count, West Virginia. Use of the name, Rochester Fornation is restricted to the New York section. The succession of conodont faunas described for these formations range from latest Wenlock through Pridoli in age. The fauna includes 46 form species assignable to the form genera Hindeodella, Ligonodina, Lonchodina, Neoprioniodus, Ozarkodina, Panderodus, Plectospathodus, Spathoenathodus, and Trichonodella. Sixteen new form species are described and twelve of these are named: Ligonodina brevis, Ozarkodina edithae mariae, Q. typica intermedia, O. serrata, Q. sinuosa, O. ziegleri crassatoides, Spathognathodus bicornutus, S. primus highlandensis, S. primus multidentatus, S. tillmani, S. walliseri, and Synprioniodina lowryi. One platform species, possibly representing a new form genus, occurs in the upper Tonoloway Formation. The important European forms Spathognathodus sagitta bohemicus., S. snajdri, S. crispus, and S. steinhornensis eosteinhornensis, are reported for the first time from the Central Appalachians. Eleven multi-element conodont species are recognized using open nomenclature. The faunas of the S. sagitta bohemicus, S. snajdri, S. crispus, and S. steinhornensis eosteinhornensis zones correlate with the sagitta, snajdri horizon of the siluricus, crispus, and eosteinhornensis zones of Walliser. The S. bicornutus and S. tillmani zones are tentatively correlated with Walliser's crassa and latialatus zones. The ploeckensis Zone of Walliser was not identified, but its stratigraphic position would be similar to that of the unzoned interval of the middle third of the McKenzie Member of the Mifflintown Formation. Ph. D.