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The Starkville Quadrangle is a hotspot for geological research. The Late Cretaceous is represented by the Demopolis Formation in the northeast corner of the quadrangle, followed by the Ripley Formation, and the Prairie Bluff Formation. The K-Pg boundary is exposed in the quadrangle, and the remarkable paleontology is of global importance. The Clayton Formation is the first Paleocene unit. Where the Clayton Formation channel sands are in contact with the underlying Prairie Bluff Formation, springs occur. Springs were a rare source of water in the Black Prairie and spurred the settlement of the area over 10,000 years ago. The Paleocene Porters Creek Formation occurs in the southwest corner of the Quadrangle. Quaternary streams left Holocene to Pleistocene alluvium and terraces overlying the subcrop. This project provides a modern geologic map and stratigraphic framework as a background for future research in the Starkville Quadrangle.

For the same reasons which prompted its ratification in 1990 as the Global Stratotype Section and Point for the Mid-Carboniferous boundary, namely, section completeness, abundant fossils, and excellent exposure, the Morrowan Arrow Canyon Bird Spring strata is recommended as a candidate standard sequence stratigraphic reference for the Morrowan portion of the Lower Absaroka I supersequence. The stratigraphic architecture of Morrowan strata in Arrow Canyon was largely controlled by high-amplitude (100-m), high-frequency sea-level changes. Outcrop data and facies stacking patterns define 59 fifth-order fundamental cycles. These fundamental cycles stack into ten third-order sequences with an average duration of 320 ka. Changes in both cycle thickness and fundamental cycle type indicate that the second-order sea-level curve of Golonka and Keissling for the Lower Absaroka Ia supersequence should be modified to reflect rising sea-level from the Mid-Carboniferous boundary with maximum flooding conditions ~120 to 135 meters above the Mid-Carboniferous boundary, followed by falling sea-level to ~6 meters below the Morrowan-Atokan boundary in Arrow Canyon. Additionally, cycle diagnostic conodonts and foraminifera permit correlation of selected third-order sequences to basins containing time-equivalent strata.

Pliocene-Pleistocene sediments in the southeastern Acambay graben, central Mexico have yielded mammal fossils, including Equus simplicidens, cf. Rhynchotherium, ?Camelops, Mammuthus sp., Bison sp., and Antilocapra sp. The fossiliferous sediments include a period of lacustrine sedimentation in the late Pliocene-early Pleistocene that interrupted fluvial and alluvial sedimentation during the early Pliocene and Pleistocene. The sediments deposited in this late Pliocene paleolake record a history of lake level fluctuations, shown by lithologic variations in lacustrine sediments and abundance of vertebrate burrows. Volcanic and tectonic events in the Acambay graben were the major controls on sedimentation during Pliocene-Pleistocene time. Various local volcanic structures produced source rocks for Pliocene-Pleistocene sediments, and intra-arc extensional tectonics caused basin subsidence. Blockage of stream drainages by lava flows or perhaps increased basin subsidence contributed to the appearance of and fluctuations in the lacustrine system during the late Pliocene. Diatom assemblages from lacustrine sediments indicate slightly higher precipitation and humidity than present-day conditions in the Acambay graben. Therefore, climatic forcing may have also contributed to the development of the late Pliocene paleolake in the Acambay graben. Pliocene-Pleistocene volcanic rocks in this part of the Acambay graben range from basaltic andesite to rhyolite. The calc-alkaline composition of these volcanic rocks is similar to others in the modern Mexican Volcanic Belt; they have a continental arc affinity, which is consistent with a tectonic setting within the Mexican Volcanic Belt. The major eruptive episode in the Acambay graben occurred during the early Pliocene, although volcanism, represented by small volcanic structures, continued until the late Pleistocene. This observed decline in volcanism in the Acambay graben correlates with a early Pliocene through Quaternary trenchward migration of volcanism in the Mexican Volcanic Belt.

The Wattis 7.5 Minute Quadrangle is located in central Utah, in the transition zone between the Basin and Range province and the Colorado plateau. Two small grabens, located in the quadrangle, are the easternmost evidence of Basin and Range faulting. Sedimentary units exposed are mainly Cretaceous in age and deposited in the Western Cretaceous Interior Seaway. This area is of economical importance due to its large coal deposits, coal bed methane, and groundwater. The Wattis Quadrangle provided an ideal opportunity to test, at a small scale, the applicability of a new groundwater model for stratified mountainous terranes. Water samples had 14C ages ranging from modern to 10,000 ± 500 years. Stable isotopes of oxygen and hydrogen showed that recharged precipitation fell when climate conditions were close to modern, or slightly colder. Three groundwater systems consist of one shallow groundwater system in the North Horn Formation, and two deeper aquifers located in the Blackhawk Formation and the Star Point Sandstone. Water in the North Horn Formation is modern, whereas the Blackhawk Formation and Star Point Sandstone waters are mixed systems, having tritium concentrations between 3 and 4 T.U., and 14C ages between 7,000 and 10,000 years. Geochemical modeling shows that there are no plausible reaction paths to evolve the North Horn Formation waters into waters contained in underlying units. Thus, water entering the top of the plateau does not flow through the stratified rocks to exit at its base. Instead, the waters represent discrete perched systems at various stratigraphic levels. The Star Point Sandstone has three parasequences with a single sequence boundary. The deposits show normal marine conditions containing lower shoreface biota of Skolithos and Ophiomorpha overlain by middle shoreface sedimentary structures. The Star Point Sandstone deltaic parasequences likely prograded into the basin during pulses of thrusting from the Sevier Orogeny. The Emery Sandstone Member of the Mancos Formation contains three parasequences all located in the lower shoreface, and also exhibits the normal marine biota of Skolithos and Ophiomorpha. The Emery Sandstone reflects density currents caused by major storm events, including Bauma C and D depositional structures. Thick sandstone bodies are restricted to paleochannels.

The Early Pennsylvanian (Bashkirian/Morrowan) Round Valley Limestone of northeastern Utah was deposited on the Wyoming shelf, a slowly subsiding depositional surface located between the Eagle and Oquirrh basins. The 311-foot-thick Round Valley Limestone displays a distinct cyclicity formed by stacked, meter-scale parasequences, comprised of a limited suite of open- to restricted-marine limestones with minor interbeds of siltstone and shale. Open-marine deposits are characterized by mudstone and heterozoan wackestone-packstone microfacies (MF1-4) and comprise the lower portions of parasequences. Rocks of these microfacies were deposited during maximum high-order transgression of the shelf. As sediment filled the limited accommodation, the shelf became restricted, leading to deposition of mollusk-peloid dominated wackestone microfacies (MF6). Grainstones (MF5) microfacies are volumetrically limited in the Round Valley and represent deposition on isolated sand shoals that populated the shallow shelf. The complete Round Valley section at Split Mountain in Dinosaur National Monument is comprised of 5 intermediate-order sequences and 48 higher-order parasquences. Twenty-one of the shallowing-upward cycles are bounded by exposure surfaces as indicated by the occurrence of rhizoliths, glaebules, autobreccia and alveolar structures. Four of these that also indicate a significant drop in sea level (abnormal subaerial exposure surfaces and surfaces with erosional relief) constitute candidate sequence boundaries. The high percentage of cycles capped by exposure surfaces indicates that deposition of the Round Valley took place intermittently and that the Wyoming shelf was exposed during a significant portion of the Bashkirian epoch. Intermittency of deposition is confirmed by comparing the thickness and sequence architecture of the Round Valley Limestone with coeval strata in the eastern Oquirrh basin (Bridal Veil Limestone). The Bridal Veil Limestone is four times thicker and contains 24 cycles not represented on the Wyoming shelf.

Multiple shallow sediment cores were obtained from Pilot Valley playa, a sub-basin located in the northwestern Bonneville basin. Analysis of stratigraphy, ostracodes, mineralogy, chemistry, total inorganic carbon (TIC), total organic carbon (TOC), and stable isotopes were performed to better place these sediments into proper context with respect to the Lake Bonneville cycle. Results showed Pilot Valley playa contains a nearly full sequence of Lake Bonneville deep-water marl in addition to sediments deposited before and after the Lake Bonneville cycle. Within the marl is a sequence of organic rich algal laminated marl correlated with the Stansbury oscillation. Four 14C ages ranging from ~22.4 k 14C years to ~15.8 k 14C years from preserved algae filaments in this sequence place it well within the time frame of the Stansbury oscillation. Oolitic sand found below this sequence indicates the existence of a shallow (<~5 m), saline lake in Pilot Valley prior to the transgression of Lake Bonneville. Analysis of sediments deposited during the late regressive phase of Lake Bonneville indicates the lake may have fallen to levels below that of Pilot Valley prior to transgressing to the Gilbert level.

Since the early days of the discovery of the Gray Fossil Site (GFS), meticulous efforts to preserve the spatial data were a priority. Direct surveying of fossils prior to recovery, as well as grid mapping the site, provided relative spatial data within a square meter. Such efforts meant that even fragments and microfossils, recovered during the screening operations and eventual concentrate picking, maintained some spatial data. Available spatial data are used to identify smaller deposits within the greater system, as well as non-random distribution patterns among a number of GFS taxa. Patterns are particularly pronounced in the large-bodied taxa, Teleoceras aepysoma and the GFS mammutid, as well as microvertebrates. Results suggest that controlling factors include taphonomic constraints related to body size, proximity to near-shore or shallow areas, underlying geological features, and to a lesser extent “ecological role”. Results of this research may help guide future excavation and collection methods.

Excavations at Natural Trap Cave (NTC) began in the mid-1970's and quickly yielded evidence of a diverse steppe fauna that existed during the Last Glacial Maximum (MIS 2) along the western slope of the Bighorn Mountains in north central Wyoming. NTC is a karst pit cave with a 24.5 m vertical drop into a roughly 43 m wide bell-shaped ‘Main Chamber’ and during the course of early excavations a plugged entrance to a fossil-bearing ‘Lower Chamber’ was discovered. Stratigraphic relationships below the entrance to the Main Chamber of the cave were originally studied in the mid-1970's, but were never formally published. Although stratigraphy, taphonomy, and depositional circumstances were briefly discussed over the following years, little has been done to correlate the numerous stratigraphic schemes used by various authors. In this study, four stratigraphic sections were measured and analyzed to establish an easily modifiable lithostratigraphic system of nomenclature. We provide the first correlations of all stratigraphic nomenclature used throughout excavations at NTC to facilitate comparisons with current and previous collections and publications. By leveraging more than 100 radioisotopic dates we developed an age-depth model and chronostratigraphic framework to further interrogate spatiotemporal relationships between strata, paleoenvironmental proxies, and fossil assemblages. Deposition is shown to be discontinuous; sediment accumulation in the study area is restricted to the buildup through peak penultimate and Last Glacial maxima. More recent (<10 ka) Holocene deposits unconformably cover the eroded surface of underlying Pleistocene strata. There is active reworking of sediments with transport and deposition of reactivated material within the Lower Chamber. We note that the two hiatuses coincide with interglacial periods and may reflect changing depositional circumstances within the cave such as extended periods of non-deposition, erosion, or bypass (possibly leading to deposition in the Lower Chamber). Contrary to previous reports, we demonstrate that it is unlikely a prominent snow cone existed or contributed to the pattern of sediment and fossil distribution within the study area, furthermore, we do not observe a continuous Pleistocene-Holocene transition in the study area. Further stratigraphic work will be needed to better understand the interrelationship between Main and Lower chamber deposits and the evolution of sediment accumulation in NTC.

Early Pennsylvanian, coal-bearing, siliciclastic strata of the Breathitt Group within the Pocahontas Basin, southwestern Virginia, define a southeasterly thickening clastic wedge deposited in continental to marginal marine environments influenced by recurring, high-magnitude relative sea-level fluctuations and low-frequency changes in tectonic loading. A robust dataset of >1200 well logs, cores and numerous outcrops allowed a unique review of the Central Appalachian lithologic record during both the Late Paleozoic Ice Age and onset of the Alleghanian Orogeny. The tropical depositional landscape produced stacked deposits of braided-fluvial channels, broad alluvial plains, tidally-influenced estuaries and small deltas. Trends in facies associations allowed development of a high-resolution sequence stratigraphic architecture based on regional flooding surfaces and bounding discontinuities. Analysis of vertical stacking patterns of lithofacies on regional cross-sections identified 15 widespread, unconformity-bounded depositional sequences with an average duration of ~80 kyr based on available geochronology. Glacioeustatic control on stratigraphic architecture is supported by corresponding sequence duration within the short-eccentricity periodicity of the Milankovitch band, as well as the magnitude and extent of rapid facies shifts, suggesting that far-a-field variations in overall Gondwanan ice-sheet size and volume impacted base-level changes in the tropical basin. The progressive increase in magnitude of transgressions, as indicated by brackish-marine ichnofacies and other faunal indicators within regional high-frequency transgressive system tracts, indicate extrabasinal trends in ice-volume and eustasy. High-frequency eustatic sequences are nested within four asymmetric composite-sequences, attributed to low-frequency variations in tectonic accommodation. Evidence for tectonic forcing on foreland-basin accommodation is based on abrupt facies shifts, angular stratal terminations and wedge-shaped composite-sequence geometries. Spatial and temporal trends in facies associations within composite-sequences reveal episodic variation in tectonic loading overprinted by recurring high-frequency eustatic events. Petrology and detrital-zircon geochronology indicates that sediment was derived from low-grade metamorphic Grenvillian-Avalonian terranes and recycling of older Paleozoic sedimentary rocks uplifted as part of the Alleghanian orogen towards the southeast and, in part, from the Archean Superior Province to the north. Applications of the observed facies distribution and petrophysics of these coal-bearing sedimentary rocks indicate numerous confining intervals within regional mudstones overlying coalbeds, suggesting the potential for beneficial geological storage of CO2 through enhanced-coal-bed-methane recovery. / Ph. D.