Investigations Into The Advancement Of Cryptotephra Geochemical Fingerprinting, Laura Hartman

Electronic Theses and Dissertations

The primary purpose of this work is to advance new sample preparation and analytical methods for ice core tephrochronology. When a volcanic source can be accurately identified using volcanic glass particle geochemistry, it may provide a robust time reference for the ice core’s timescale. The presence of an identifiable tephra layer may also suggest atmospheric pathways at the time of deposition, or assist in reconstructing volcanic forcing of climactic state for a specific event. One of the perpetual challenges in ice core based tephrochronological work is measuring the geochemical composition of ultra-fine particles (<10 >μm). Not only is it difficult …

Remote Sensing Of Icebergs In Greenland's Fjords And Coastal Waters, Jessica Scheick

Electronic Theses and Dissertations

Increases in ocean water temperature are implicated in driving recent accelerated rates of mass loss from the Greenland Ice Sheet. Icebergs provide a key tool for gaining insight into ice-ocean interactions and until recently have been relatively understudied. Here we develop several methods that exploit icebergs visible in optical satellite imagery to provide insight on the ice--ocean environment and explore how iceberg datasets can be used to examine the physics of iceberg decay and parent glacier properties. First, a semi-automated algorithm, which includes a machine learning-based cloud mask, is applied to six years (2000-2002 and 2013-2015) of the Landsat archive …

Stream Dynamics In The Headwaters Of Post-Glacial Watershed Systems, Brett Gerard

Electronic Theses and Dissertations

This dissertation summarizes research examining watershed processes across Northern New England, with an emphasis on the Central and Coastal regions of Maine. The research presented here focuses on the linkages between watershed geomorphic conditions, climate, and surface flow regimes driving stream channel hydraulic conditions and bed dynamics governing channel geometry. The geologic and human history of the landscape provides the context in which earth surface processes are examined within the dominant physiographic settings in Maine to describe vulnerabilities to climate change. Results are summarized to support the development of sustainability solutions for forecasted watershed management problems by natural resource management …

Controls On Phosphorus Export From An Agricultural Watershed: Amsden Brook, Fort Fairfield, Maine Usa., Gregory J. Mcdonald

Electronic Theses and Dissertations

This study explores the sources and mechanisms of phosphorus (P) mobilization during base flow within the Amsden Brook watershed, Fort Fairfield, Maine, USA. Amsden Brook is an agriculturally dominated watershed drained by a spring-fed and perennial first- to second-order stream. We characterized the P concentrations within the watershed to investigate connections between soils, stream sediment, surface water, and groundwater. Waters were monitored monthly during the 2017 snow-free period for temperature, pH, dissolved oxygen, conductivity, soluble reactive P (SRP), total P, strong acid anions, strong base cations, dissolved organic carbon (DOC), Al, Fe, and Mn. Phosphorus speciation within soils and sediment …

Mercury In Big Cypress Bayou And Caddo Lake Watersheds In Marion And Harrison Counties Texas, Joseph Watkins

Electronic Theses and Dissertations

Caddo Lake has been included on the Texas Commission on Environmental Quality 303(d) list for impairment due to mercury (Hg) content since 1996. One of the primary tributaries, Big Cypress Bayou, flows across Eocene-aged rocks and sediments associated with the Wilcox Group; the Wilcox is of interest because it contains lignite coal, which has a direct link to mercury. Previous research has focused on dry deposition from fossil fuel combustion as the primary source of mercury but has not addressed the potential watershed contribution to mercury concentrations in Caddo Lake.

Big Cypress Bayou flows through Harrison and Marion counties in …

Delineation Of Karst Potential Using Lidar And Gis Analyses, Fort Hood Military Installation, Texas, Colby Reece

Electronic Theses and Dissertations

ABSTRACT

Traditional karst surveys require extensive field investigations to completely characterize large areas. They are often time-consuming, requiring up to several years to collect and categorize data. Bias is given to areas that are most easily accessible and false negatives are common. The implementation of geographic information systems (GIS) has aided in the aggregation and standardization of karst data; however, these systems have also been used to develop terrain models that allow the user to remotely delineate sinkholes and other surficial features. The Fort Hood Military Installation is a karst landscape that has been altered significantly for use in military …

Climatic Range Filling Of North American Trees, Benjamin Seliger

Electronic Theses and Dissertations

Understanding the degree to which species distributions are controlled by climate is crucial for forecasting biodiversity responses to climate change. Climatic equilibrium, when species are found in all places which are climatically suitable, is a fundamental assumption of species distribution models, but there is evidence in support of climate disequilibria in species ranges. Long-lived, sessile organisms such as trees may be especially vulnerable to being outpaced by climate change, and thus prone to disequilibrium. In this dissertation, I tested the degree to which North American trees are in equilibrium with their potential climatic ranges using the ‘range filling’ metric, which …

An Outcrop Based Study Of The Weches Formation In Sabine County, Texas: Investigating Its Unconventional Resource Potential Through The Study Of Stratigraphy, Sedimentology, Petrology, And Geochemistry, Talban Kantala

Electronic Theses and Dissertations

Fresh Weches Formation (Middle Eocene) exposures found in aggregate quarries in Sabine County, Texas, were sampled, measured, and logged with gamma-ray spectrometry (GRS). Sedimentology and petrology characteristics of Weches samples were analyzed through thin section, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and GRS Th/K ratios analyses. The source rock quality of the Weches was evaluated with geochemical techniques involving total organic carbon (TOC), Rock-Eval pyrolysis, and GRS Th/U ratios.

The Weches, in the study area, is 27.4 meters thick, and delineated into three major stratigraphic facies: an upper marginal marine prodeltaic facies (Therrill Member) comprised of silty claystones and …

Physical And Chemical Controls On Suffosion Development In Gypsic Soil, Culberson County, Texas, Jonah Morris

Electronic Theses and Dissertations

In the Gypsum Plain, suffosion processes have encouraged road failure through dissolution and transport of gypsic soils; however, no prior research has been conducted within the Delaware Basin in regard to these processes. These phenomena were evaluated in both field and laboratory settings in order to assess the parameters of suffosion development associated with Ranch to Market (RM) 652 in Culberson County, Texas, where infrastructure extends across Castile and Rustler strata. Field studies simulated surficial ponding in various gypsic soils and correlated suffosion potential with soil composition and thickness. Soluble fractions of gypsic soils were delineated through geochemical analyses, further …

Depositional Environment And Facies Analyses Of The Owl Mountain Province, Fort Hood Military Installation, Bell And Coryell Counties, Texas, Jacob Meinerts

Electronic Theses and Dissertations

The Owl Mountain Province is a plateaued, karst landscape located in the eastern section of the Fort Hood Military Installation and is characterized by Lower Cretaceous Fredericksburg Group carbonates. The topography is capped by thick sequences of the Edwards limestone; steep scarps and incised valleys along the edges of the plateaus host inter-fingering outcrops of the Edwards and Comanche Peak limestones, and the lower valleys are covered by alluvial sediments and intermittent outcrops of the Walnut Clay. These formations were deposited to the north and west of the main Edwards trend, and are thought to be part of a series …

The Effects Of Seasonal Variations In Chemistry And Hydrology On The Microbial Community And Its Sulfide Oxidation Potential In A Naturally Acidic Maine Stream, Raymond C. Kahler Iii

Electronic Theses and Dissertations

Sulfide minerals oxidize through interaction with water and oxygen, releasing hydrogen ions. The process often occurs naturally near metal sulfide deposits, and can be accelerated through mining. Microorganisms accelerate the rate of sulfide oxidation. Acidified streams typically contain high metal concentrations (e.g. aluminum) and microbes in these systems may develop resistances to metal toxicity. Stream flow can affect sulfide oxidation and microbial community structure. Baseflow can influence stream chemistry from interactions with the surrounding bedrock, while stormflow affects stream chemistry and the local microbial community through dilution and addition of microbes transported by runoff. Microbial community composition is affected by …

Three-Dimensional Bedrock Channel Evolution With Smoothed Particle Hydrodynamics, Nick Richmond

Electronic Theses and Dissertations

Bedrock channels are responsible for balancing and communicating tectonic and climatic signals across landscapes, but it is difficult and dangerous to observe and measure the flows responsible for removing weakly-attached blocks of bedrock from the channel boundary. Consequently, quantitative descriptions of the dynamics of bedrock removal are scarce. Detailed numerical simulation of violent flows in three dimensions has been historically challenging due to technological limitations, but advances in computational fluid dynamics aided by high-performance computing have made it practical to generate approximate solutions to the governing equations of fluid dynamics. From these numerical solutions we gain detailed knowledge of the …

Improving Sinkhole Mapping Using Lidar Data And Locating Sinkhole Hotspots In Johnson City, Tn, Kingsley Fasesin

Electronic Theses and Dissertations

Predicting infrastructure damage and economic impact of sinkholes requires high accuracy mapping distribution and development. The study mapped sinkholes and sinkhole hotpsots in Johnson City, TN using LiDAR-derived Digital Elevation Model (DEM) and a database of known sinkholes which were matched to LiDAR-derived depressions. For all matched depressions (n = 404), three metrics were calculated: circularity index, ratio of length to width of the Minimum Bounding Rectangle (MBR) and percent coverage of the MBR by the depression, and 3,634 new sinkholes were identified. Newly developed hotspots were identified in north Johnson City and other areas in the south near the …

Groundwater Hydrogeolgy And Hydrochemistry Of Karst Springs In The Eastern Peninsula Of Fort Hood Military Installation, William Scribner Welles

Electronic Theses and Dissertations

The eastern peninsula of Fort Hood Military Installation is underlain by a complex karst spring network. These springs are a primary water source in a protected habitat for endangered songbirds, which has only recently begun to be fully investigated. These Fredericksburg Group springs express both epigenetic and hypogenetic karst signatures. The study area is part of a paleo reef trend, a hydraulically disconnected segment of the northern section of the Edwards Aquifer. This study utilized standard ion index values, repeated measures, and principal component analyses on the chemical profiles of six perennial springs to classify spring water sources and their …

Modern And Paleoecological Perspectives On A Terrestrial-Marine Linkage In The Falkland Islands, Dulcinea V. Groff

Electronic Theses and Dissertations

The Falkland Islands are a biodiversity hotspot in the South Atlantic Ocean, with some of the world’s most important populations of seabirds and seals. The impact of climate change on these marine populations and their coastal breeding habitat in the Falklands is unknown. Coastal grasslands of Poa flabellata (tussac grass) form critical breeding habitat for wildlife, but have been heavily degraded by the introduction of livestock in the 17^th century. This dissertation investigates the impacts of global change (climate change, grazing) on P. flabellata and its sensitivity to the fecal nutrient subsidies provided by marine wildlife. Chapter 1 provides …

Late Holocene Spit Evolution On Centennial Timescales In The Southeast Delaware Bay, Usa, Ryan Eli Phillip

Electronic Theses and Dissertations

The relationship between barrier spit growth and longshore drift is well established. However, the role of storm activity in spit evolution on an intermediate (centennial) timescale is more of a mystery due to a knowledge gap between decadal-scale shoreline processes and millennial-scale stratigraphic data. Recent studies in the northwestern Atlantic basin using ground-penetrating radar (GPR) and optically-stimulated luminescence (OSL) are providing the opportunity to study centennial-scale shoreline evolution and examine similar age storm activity. Cape Henlopen, Delaware exhibits preserved remnants of a long-term northward-growing spit coastline that evolved from a recurved spit complex, to a cuspate spit, to the present-day …

Nitrogen Cycling During A Period Of Environmental Change, Kaizad Patel

Electronic Theses and Dissertations

Natural and anthropogenic disturbances have altered the N cycle on the regional to global scale. Although numerous studies have examined the effects of chronic atmospheric N deposition on ecosystem processes, less is known about intra-annual variability of these processes, or how these responses might be altered under conditions of changing climate. The work described in this dissertation focuses on the effects of a changing chemical and physical climate, particularly terrestrial N processes (a) during Maine’s changing winters, and (b) in response to chronic elevated N additions.

Subnivean winter soil processes were examined at the Dwight B. DeMerritt Forest (DBDF) and …

Retreat Of The Antarctic Ice Sheet In The Southern Ross Embayment From Records At Amundsen And Liv Glaciers, Southern Transantarctic Mountains, Jillian Pelto

Electronic Theses and Dissertations

The Antarctic Ice Sheet contains ~58 m of global sea-level equivalent and thus its future behavior under global warming is of pressing concern. Examination of past ice-sheet behavior during periods of warming climate can afford insight useful for predicting future sea-level rise. This study focuses on a major unanswered question - namely, the cause of Antarctic Ice Sheet retreat following the last glaciation. Documenting the timing and nature of this deglaciation is crucial to understand the mechanisms behind ice-sheet behavior. Here, I examine how the marine portions of the ice sheet responded to the major warming that occurred at the …

Warning Confidence And Perceptions Of Lava Flow Hazard Diversion Strategies At Kīlauea And Mauna Loa Volcanoes, Hawai‘I, Ashleigh Reeves

Electronic Theses and Dissertations

The 2014-15 lava flow crisis at Kīlauea volcano, Hawai‘i and post-September 2015 elevated unrest at adjacent Mauna Loa volcano provided opportunities to assess households’ psychological and behavioral responses to different levels of volcanic activity. Weused the Protective Action Decision Model to examine stakeholder perceptions and confidence in warnings, in addition toattitudes toward lava flow mitigation strategies, such as diversion by berms and bombing, and people’s acceptance of additional risk to personal property in exchange for protecting important elements of their community, such as schools, major roads, electrical substation, and shopping centers. Respondents’ confidence in events important in decision-making during emergencies …

Fault-Adjacent Damage At The Base Of The Seismogenic Zone And Seismic Anisotropy Of Fold Structures, Won Joon Song

Electronic Theses and Dissertations

While earthquakes represent a major hazard to life and property, there are a number of open questions about how earthquake faults operate at depth, and how the energy released by earthquakes travels as elastic waves through Earth’s complexly deformed crustal rocks. The aims of my dissertation are to explore (a) the extent of co-seismic damage in an ancient earthquake fault exhumed from great depths, (b) the deformation processes and mechanics of the fault at depth during earthquake cycles, and (c) the role of different rock structures in determining the velocities of seismic waves.

When tectonic plates collide, deformation tends to …

A Glacial History Of Roberts Massif, Central Transantarctic Mountains, Antarctica, Using Cosmogenic 3he, 10be, And 21ne Surface Exposure Ages, Alexandra M. Balter

Electronic Theses and Dissertations

Ice-free areas at high elevation in the central Transantarctic Mountains preserve moraines and drift deposits that delineate the former thickness and extent of the East Antarctic Ice Sheet (EAIS); cosmogenic exposure ages on these features indicate when the ice sheet was as or more extensive than today. Approximately 30 existing cosmogenic-nuclide exposure ages from scattered locations within these deposits suggest that some moraines and drift sheets are at least 5 Ma old. Those ages imply that the age range of these deposits may span warm periods during the Miocene and Pliocene, during which the EAIS is hypothesized to have been …

Holocene Formation History Of Mud Depocenters On The Continental Shelf In The Gulf Of Cadiz, Southwestern Spain, Mary Lee King

Electronic Theses and Dissertations

Holocene mud accumulation on the continental shelf in northern Gulf of Cadiz, from the Guadalquivir River to the Tinto-Odiel Estuary, is described as two types of mud depocenters (MDCs): a sheet-like prodelta and mud belt. Despite a substantial number of investigations of this continental shelf (Somoza et al., 1997; Hernández-Molina et al., 2000; Lobo et al., 2001; synthesis: Lobo et al., 2015), information on Holocene sediment facies and a robust stratigraphic age model remained unestablished (Lobo et al., 2002; and Lobo and Ridente, 2014). Objectives of this study are to describe the dynamics of MDC formation in a chrono- and …

Hardbottom Characterization And Relationship To The Geologic Framework In Long Bay, South Carolina, Cathryn J. Wheaton

Electronic Theses and Dissertations

Hardbottom seafloor is a common element among sediment-starved portions of the inner continental shelf along the U.S. Atlantic margin. These areas are characterized by indurated sediment surfaces that are heavily altered by biological and physical processes. Long Bay, in northeastern South Carolina, offers ideal environmental conditions for hardbottom exposure with only patchy Holocene sand deposits, interspersed with extensive hardbottom areas. Here we use high-resolution multibeam bathymetry, CHIRP subbottom profiling and electrical resistivity data, along with surficial sediment samples, hardbottom thin sections, and water column radioisotope (radon-222) analysis to investigate the origin and geologic framework of a region of hardbottom seafloor …

A Geophysical Delineation Of A Normal Fault Within The Gulf Coastal Plain, Montgomery County, Texas, Danielle Minteer

Electronic Theses and Dissertations

The Gulf Coast of Texas has been a known hydrocarbon basin for many years with various structural trapping mechanisms such as anticlines, faults and salt domes. While most large salt domes have been extensively studied in the Gulf Coastal Plain, many smaller normal faults have not been studied in detail. This research study employs an integrated geophysical approach to mapping the Big Barn fault in Montgomery County, Texas. This fault is located on the Gulf Coastal Plain and is approximately 20 miles north of Houston, Texas. Most normal faults in the Gulf Coastal Plain formed as a result of the …

Speleogenetic Evolution And Geological Remote Sensing Of The Gypsum Plain, Eddy County, New Mexico, Jessica Shields

Electronic Theses and Dissertations

Permian evaporites of the Gypsum Plain region of the Delaware Basin host extensive karst phenomena, as well as unique diagenetic alterations of host strata. Because of the complex, poorly understood hydrogeologic system, little has been established concerning the relation and evolution of the overprinted, modern and ancient karst manifestations within the Gypsum Plain, as a whole. Through a combination of traditional field studies and the development of improved remote sensing methodologies, this study established the speleogenetic evolution of the Gypsum Plain in relation to the greater tectonic, stratigraphic, hydrogeologic and climatic history of the Delaware Basin. Emphasis was focused on …

Developing A Risk Assessment Protocol To Quantify Distribution And Uptake Of Persistent Organic Pollutants In Glacial Outflows, Kimberley Rain Miner

Electronic Theses and Dissertations

Pollutants released by industrialized nations between 1960 and 2004 have been transported northward through atmospheric processes and deposited into glaciated alpine ecosystems. Many of these chemicals retain their original structure and are absorbed into the biota thousands of miles away from where they were originally utilized. With a warming climate increasing the melt of alpine glaciers, these glaciers may be introducing growing amounts of toxins into the watershed. While studies have demonstrated the existence of resident pollutants within glaciated ecosystems, no one has developed a risk assessment to identify sources and quantity of risk posed by these compounds when released …

Assessing The Reliability Of The Benthic Mg/Ca–Temperature Proxy: A Uvigerina Core-Top Study From New Zealand, Cassandre R. Stirpe

Electronic Theses and Dissertations

Sediment cores from New Zealand’s Bay of Plenty and the Chatham Rise in the Southwest Pacific were sampled to establish a regional Mg/Ca–temperature calibration for the benthic foraminifer Uvigerina peregrina. Comparison of foraminiferal Mg/Ca from core-top sediments to local bottom water temperatures reveals a Mg/Ca–temperature relationship broadly consistent with previously published calibrations. In addition to bottom water temperatures, other environmental parameters are examined for possible influence on the Mg/Ca of foraminiferal calcite. Elderfield et al. (2006) proposed that such parameters may exert an influence at colder temperatures, particularly below temperatures of ~3oC (e.g. Lear et al., 2002; Elderfield et al., …

Utilizing Ground-Penetrating Radar In The Delineation And Cultural Resource Management Of Eroding Maine Coastal Shell Middens, Jacquelynn F. Miller

Electronic Theses and Dissertations

Shell middens along the Maine coast archive up to 5000 years of cultural and climatic change, but the record is continually and rapidly lost to the sea through climate-driven coastal erosion and sea-level rise. These sites were constructed by the ancestors of Maine Tribes, and are composed of centimeters to meters of clam (Mya arenaria) and/or oyster (Crassostrea virginica) shells, other faunal remains, and cultural materials. Shell middens record human interaction with the environment and early coastal occupation and adaptation. The faunal remains reflect paleoenvironmental conditions and the distribution of extinct and extant forage-species along the western Gulf of Maine. …

Petrographic And Stratigraphic Analysis Along The Lower Cretaceous Strata, In Kimble County Texas, Austin C. Wilkerson

Electronic Theses and Dissertations

The upper Trinity Group is predominantly a carbonate system with minor clastic couplets that were deposited during the Middle Cretaceous in the south Llano Uplift region. The upper Trinity Group was deposited on a southward dipping platform in the Kimble County area. Stratigraphic units of the upper Trinity Group are the Hensel Formation, determined to be supratidal claystones, the Glen Rose Formation, which are mudstones that were deposited in a carbonate lagoon, and the Walnut and Fort Terrett formations, which are wackestones to packstones interpreted to have been deposited on a shallow carbonate shelf.

Nine stratigraphic sections were measured along …

Postcranial Morphology And The Locomotor Adaptations Of Extant And Extinct Crocodylomorphs And Lepidosaurs, Laura Rooney

Electronic Theses and Dissertations

I have collected a series of linear measurements of the postcranial skeletons of 43 extant crocodylian and lepidosaur taxa to determine if those engaging in similar locomotor behavior display similar morphology despite phylogenetic differences. Stepwise discriminant function analyses reveal reptile locomotor mode can be accurately predicted (over 80% correct) based on morphology. Semi-aquatic taxa are distinguished by a longer ischium relative to pubis length, a longer scapula relative to humerus length, and a broader acetabulum than terrestrial and arboreal taxa. Arboreal taxa display a more elongate, gracile humerus and a smaller acetabulum. This morphometric data can potentially be used to …