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2020

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Articles 1681 - 1710 of 3204

Full-Text Articles in Earth Sciences

Wildlife Use Of Road Mitigation Structures In Relation To Their Construction, Structural Characteristics, And Environmental Factors Along A South Texas Highway, Anna D. Rivera Roy May 2020

Wildlife Use Of Road Mitigation Structures In Relation To Their Construction, Structural Characteristics, And Environmental Factors Along A South Texas Highway, Anna D. Rivera Roy

Theses and Dissertations

Roads are known to negatively impact wildlife by fragmenting habitat and mortality caused by wildlife-vehicle collisions. Road mitigation structures, such as wildlife crossing structures (WCS), wildlife guards (WG), and fencing are commonly used to address the issue of roads. In South Texas, such structures were built or modified along State Highway (SH) 100 in Cameron County as an effort to conserve the endangered ocelot (Leopardus pardalis). Camera traps were deployed to monitor these structures as a way to assess their effectiveness in restricting wildlife entry into the roadway with fencing and WG and conveying wildlife movement across roads …


Links Between Eruptive Styles, Magmatic Evolution, And Morphology Of Shield Volcanoes: Snake River Plain, Idaho, Katelyn J. Barton, Michelle Hurst May 2020

Links Between Eruptive Styles, Magmatic Evolution, And Morphology Of Shield Volcanoes: Snake River Plain, Idaho, Katelyn J. Barton, Michelle Hurst

Utah Space Grant Consortium

Despite their similar ages and geographic locations, two low-shield volcanoes on the eastern Snake River Plain, Idaho, Kimama Butte (87 ka) and Rocky Butte (95 ka), have strikingly different profiles. In this study, these two volcanoes are examined to determine the connections between chemical composition, intensive parameters, eruption style, and topographic features of basaltic shield volcanoes. Because lava temperature, magma viscosity, and chemical composition overlap at the two volcanoes, they are probably not important controls on the differences in morphology. The main difference at the two shields, aside from general vent morphology, is the presence of late-stage, phenocryst-rich, high viscosity …


Soil Amendment And Soil Testing As Nutrient Reduction Strategies For The Peel Integrated Water Initiative, Robert Summers, Peta Richards, David Weaver, David Rowe May 2020

Soil Amendment And Soil Testing As Nutrient Reduction Strategies For The Peel Integrated Water Initiative, Robert Summers, Peta Richards, David Weaver, David Rowe

Resource management technical reports

The Transform Peel program focuses on 42 000 hectares (ha) due east of Mandurah called the Peel Food Zone, 75 kilometres (km) south of Perth in the shires of Murray and Serpentine Jarrahdale and includes an assessment of intensified and enclosed agriculture and a business park. The Peel Integrated Water Initiative was developed through Transform Peel to identify water sources and minimise the effect of these projects on water quality by reducing the nutrient loads discharged into the Peel–Harvey Estuarine System, which has been suffering from poor water quality for this reason.

The mineral sand miner MZI Resources Pty Ltd …


Geochemical Tracers Of Arctic Ocean Processes: A Study Of Gallium, Barium, And Vanadium, Laura M. Whitmore May 2020

Geochemical Tracers Of Arctic Ocean Processes: A Study Of Gallium, Barium, And Vanadium, Laura M. Whitmore

Dissertations

The Arctic Ocean is linked to the global oceans and climate through its connectivity with the North Atlantic Ocean and the regional thermohaline deep water formation sites. It’s also a region undergoing rapid environmental change. To inform the community of potential changes in geochemical and biogeochemical cycles, this dissertation addresses three dissolved geochemical tracers (gallium, barium, and vanadium) as indicators of Arctic Ocean processes. Gallium is tested as a replacement for nutrient-type tracers in an effort to deconvolve Pacific and Atlantic derived waters in the Arctic Ocean basins. These water masses carry different heat and salt content and can influence …


Climate From The Mcmurdo Dry Valleys, Antarctica, 1986–2017: Surface Air Temperature Trends And Redefined Summer Season, Maciej K. Obryk, Peter T. Doran, Andrew G. Fountain, M. Myers, Christopher P. Mckay May 2020

Climate From The Mcmurdo Dry Valleys, Antarctica, 1986–2017: Surface Air Temperature Trends And Redefined Summer Season, Maciej K. Obryk, Peter T. Doran, Andrew G. Fountain, M. Myers, Christopher P. Mckay

Geology Faculty Publications and Presentations

The weather of the McMurdo Dry Valleys, Antarctica, the largest ice‐free region of the Antarctica, has been continuously monitored since 1985 with currently 14 operational meteorological stations distributed throughout the valleys. Because climate is based on a 30‐year record of weather, this is the first study to truly define the contemporary climate of the McMurdo Dry Valleys. Mean air temperature and solar radiation based on all stations were −20°C and 102 Wm−2, respectively. Depending on the site location, the mean annual air temperatures on the valleys floors ranged between −15°C and −30°C, and mean annual solar radiation varied …


De-Icing Soil Impacts, Spring 2020, Rachel Holstein, Alex Kattan, Ali Michel, Jesse Strod May 2020

De-Icing Soil Impacts, Spring 2020, Rachel Holstein, Alex Kattan, Ali Michel, Jesse Strod

Sustainability Exchange Projects

De-Icing Impacts on the Danforth Campus, Spring 2020. Poster and presentation on de-icing impacts on Danforth Campus, Washington University in St. Louis, Sustainability Exchange, Spring 2020. Faculty Mentor: Dr. Avni Solanki


An Unusual Mastodon Revisited: Providing A Regional Focus For Mammut Americanum (Proboscidea, Mammutidae) In The Southeast, Matthew Inabinett May 2020

An Unusual Mastodon Revisited: Providing A Regional Focus For Mammut Americanum (Proboscidea, Mammutidae) In The Southeast, Matthew Inabinett

Electronic Theses and Dissertations

A century ago, two large American mastodon Mammut americanum specimens from coastal South Carolina were mounted for display at Amherst College. Their robust build, broad and pentalophodont third molars, and well-developed mandibular tusks were noted as unusual. Here, these specimens are redescribed; three additional mastodon mandibles from the same region of South Carolina are also described. Though collection information on these specimens is sparse, they appear to span >150 ka in the Middle to Late Pleistocene, and probably include the first report of Mammut from the earliest-Rancholabrean Ten Mile Hill Formation. Some “unusual” features — moderately to extremely broad third …


Detection And Enumeration Of Bacterial Pathogens In The American Oyster (Crassostrea Virginica), Mohammad Maruf Billah May 2020

Detection And Enumeration Of Bacterial Pathogens In The American Oyster (Crassostrea Virginica), Mohammad Maruf Billah

Theses and Dissertations

American oyster (Crassostrea virginica) is a popular seafood for its delicacy and high nutritional value. Based on increasing concern about contamination of bacterial pathogens in raw oyster, my research objectives have been focused on detection and enumeration of two important bacterial pathogens, Escherichia coli and Salmonella spp. in the American oyster in south Texas waters, local markets and controlled laboratory studies. Immunohistochemical and RT-PCR analyses showed substantial bacterial pathogen’s presence in gills and digestive glands of oysters collected from San Martin Lake and South Padre Island as well as local markets. Laboratory studies showed increasing trend of both …


Effects Of Arbuscular Mycorrhizal Fungi (Amf) On Growth And Herbivore Defenses In Sorghum Sudangrass (Sorghum X Drummondii), Jasleen Kaur May 2020

Effects Of Arbuscular Mycorrhizal Fungi (Amf) On Growth And Herbivore Defenses In Sorghum Sudangrass (Sorghum X Drummondii), Jasleen Kaur

Theses and Dissertations

Chapter 2: In this chapter we have examined the role of trichomes in plant stress biology, reviewed the studies on herbivore X trichome interactions, and their role in plant defences. Ultimately, we have proposed new areas of research for future work.

Chapter 3: In this chapter, we examined whether AMF has cascading effects on insect community dynamics through attraction/repulsion of beneficial and damaging insects using Sorghum-sudangrass (Sorghum x drummondii), either inoculated with commercial AMF mix or left as control in lab and field experiments. Our results suggest positive effects of AMF on plant growth, and a lower initial incidence of …


Adjusting The Lens Of Invasion Biology To Focus On The Impacts Of Climate-Driven Range Shifts, Piper D. Wallingford, Toni Lyn Morelli, Jenica M. Allen, Evelyn M. Beaury, Dana M. Blumenthal, Bethany A. Bradley, Jeffrey S. Dukes, Regan Early, Emily J. Fusco, Deborah E. Goldberg, Inés Ibáñez, Brittany B. Laginhas, Montserrat Vilà, Cascade J.B. Sorte May 2020

Adjusting The Lens Of Invasion Biology To Focus On The Impacts Of Climate-Driven Range Shifts, Piper D. Wallingford, Toni Lyn Morelli, Jenica M. Allen, Evelyn M. Beaury, Dana M. Blumenthal, Bethany A. Bradley, Jeffrey S. Dukes, Regan Early, Emily J. Fusco, Deborah E. Goldberg, Inés Ibáñez, Brittany B. Laginhas, Montserrat Vilà, Cascade J.B. Sorte

United States Geological Survey: Staff Publications

As Earth’s climate rapidly changes, species range shifts are considered key to species persistence. However, some range-shifting species will alter community structure and ecosystem processes. By adapting existing invasion risk assessment frameworks, we can identify characteristics shared with high-impact introductions and thus predict potential impacts. There are fundamental differences between introduced and range-shifting species, primarily shared evolutionary histories between range shifters and their new community. Nevertheless, impacts can occur via analogous mechanisms, such as wide dispersal, community disturbance and low biotic resistance. As ranges shift in response to climate change, we have an opportunity to develop plans to facilitate advantageous …


Tipping Points Of Mississippi Delta Marshes Due To Accelerated Sea-Level Rise, Torbjörn E. Törnqvist, Krista L. Jankowski, Yong-Xiang Li, Juan L. Gonzalez May 2020

Tipping Points Of Mississippi Delta Marshes Due To Accelerated Sea-Level Rise, Torbjörn E. Törnqvist, Krista L. Jankowski, Yong-Xiang Li, Juan L. Gonzalez

School of Earth, Environmental, & Marine Sciences Faculty Publications

Coastal marshes are threatened by relative sea-level (RSL) rise, yet recent studies predict marsh survival even under the high rates of RSL rise expected later in this century. However, because these studies are mostly based on short-term records, uncertainty persists about the longer-term vulnerability of coastal marshes. We present an 8500-year-long marsh record from the Mississippi Delta, showing that at rates of RSL rise exceeding 6 to 9 mm year−1, marsh conversion into open water occurs in about 50 years. At rates of RSL rise exceeding ~3 mm year−1, marsh drowning occurs within a few centuries. Because present-day rates of …


Hydroponic And Soilless Culture Systems And Transplant Practices Influence Production Of Basil (Omicum Basilicum L.), Samuel Warren Edward Doty May 2020

Hydroponic And Soilless Culture Systems And Transplant Practices Influence Production Of Basil (Omicum Basilicum L.), Samuel Warren Edward Doty

Graduate Theses and Dissertations

Two controlled-environment greenhouse experiments evaluated (1) plant growth and morphology of basil (Omicum basilicum L.) grown in three different hydroponic and soilless substrate systems and (2) seedling tray cell-count and transplant date into hydroponic culture effects on basil growth and yield at harvest. For the first experiment, four basil cultivars (‘Genovese’, ‘Mrs. Burns Lemon’, ‘Sweet Thai’, and ‘Cinnamon’) were grown in deep flow technique (DFT) hydroponics, nutrient film technique (NFT) hydroponics, and a novel shallow aggregate ebb-and-flood (SAEF) soilless substrate system and were harvested after 21 d. Plant yield and morphological characteristics measured at harvest included shoot fresh mass, shoot …


Survival Of Off-Host Rhipicephalus (Boophilus) Annulatus (Acari: Ixodidae) Larvae In Study Arenas In Relation To Climatic Factors And Habitats In South Texas, Usa, Emily Jesselle Zamora May 2020

Survival Of Off-Host Rhipicephalus (Boophilus) Annulatus (Acari: Ixodidae) Larvae In Study Arenas In Relation To Climatic Factors And Habitats In South Texas, Usa, Emily Jesselle Zamora

Theses and Dissertations

The cattle fever tick, Rhipicephalus (Boophilus) annulatus (Say), is an economically destructive arthropod because of its ability to vector bovine babesiosis. Cattle fever ticks can spend more than 90% of their life cycle as questing larvae, but the effect of climatic factors on their off-host behavior and survival is unclear. The goal of this study was to measure the effects of specific ecological factors on off-host larvae in nature. The study was conducted in a south Texas pasture over a 20-mo period, during which time larval populations were surveyed and ambient weather variables - relative humidity and temperatures – were …


Characterization Of Surface Karst Using Lidar And Field Traverses, Fort Hood Military Installation, Coryell County, Texas, Heather Jaclyn Dailey May 2020

Characterization Of Surface Karst Using Lidar And Field Traverses, Fort Hood Military Installation, Coryell County, Texas, Heather Jaclyn Dailey

Electronic Theses and Dissertations

The Fort Hood Military Installation is a karst landscape that has been significantly altered for training exercises that include heavy vehicle maneuvers and simulated combat. Traditional karst surveys are often time-consuming and require extensive field analyses to adequately characterize large areas. Bias is given to areas that are most easily accessible and false negatives are common. Previous studies conducted in the eastern and western portion of the base have understated the abundance and spatial distribution of karst, particularly in the western portion.

This study used field traverses and 0.5-meter Light Detection and Ranging (LiDAR) data to characterize surface karst depressions, …


Applications Of Digital Remote Sensing To Quantify Glacier Change In Glacier And Mount Rainier National Parks, Brianna Clark May 2020

Applications Of Digital Remote Sensing To Quantify Glacier Change In Glacier And Mount Rainier National Parks, Brianna Clark

Electronic Theses and Dissertations

Digital remote sensing and geographic information systems were employed in performing area and volume calculations on glacial landscapes. Characteristics of glaciers from two geographic regions, the Intermountain Region (between the Rocky Mountain and Cascade Ranges) and the Pacific Northwest, were estimated for the years 1985, 2000, and 2015. Glacier National Park was studied for the Intermountain Region whereas Mount Rainier National Park was representative of the glaciers in the Pacific Northwest. Within the thirty year period of the study, the glaciers in Glacier National Park decreased in area by 27.5 percent while those on Mount Rainier only decreased by 5.7 …


Wayne E. Sabbe Arkansas Soil Fertility Studies 2019, Nathan A. Slaton May 2020

Wayne E. Sabbe Arkansas Soil Fertility Studies 2019, Nathan A. Slaton

Arkansas Agricultural Experiment Station Research Series

Rapid technological changes in crop management and production require that the research efforts be presented in an expeditious manner. The contributions of soil fertility and fertilizers are major production factors in all Arkansas crops. The studies described within will allow producers to compare their practices with the university’s research efforts. Additionally, soil-test data and fertilizer sales are presented to allow comparisons among years, crops, and other areas within Arkansas.


An Isotopic Assessment Of Late Prehistoric Interregional Warfare In The Southcentral Us, John R. Samuelsen May 2020

An Isotopic Assessment Of Late Prehistoric Interregional Warfare In The Southcentral Us, John R. Samuelsen

Graduate Theses and Dissertations

Skull burials are found all over the world. The cause of such ancient Native Americans deposits often lead to disagreement among scholars torn between warfare and ancestor veneration. One skull-and-mandible deposit, representing at least 352 people (A.D. 1253-1399), was uncovered at the Crenshaw site, a multiple-mound Caddo ceremonial center in southwest Arkansas. Most previous research suggested they were victims of interregional warfare from the Southern Plains or Mississippi Valley. One previous study hypothesized that this was a Caddo burial practice which expanded during the Middle Caddo period (A.D. 1200-1500) due to the adoption of maize as a staple and a …


Quantifying Greenhouse Gas Emissions And Ammonia Volatilization From Soil Amended With Excreta From Ruminants Fed Alternative Forage-Based Diets, Samuel Park May 2020

Quantifying Greenhouse Gas Emissions And Ammonia Volatilization From Soil Amended With Excreta From Ruminants Fed Alternative Forage-Based Diets, Samuel Park

Graduate Theses and Dissertations

Forage-based ruminant diets supplemented with condensed tannins or polyphenolic-containing legumes may alter nitrogen (N) metabolism in the animal and reduce gas emissions from soil receiving excreta. The objective of the study was to determine if soil receiving urine or manure from sheep fed forage diets supplemented with condensed tannin or polyphenolic-containing legumes would decrease N gas emissions. Two field trials were conducted: in the first trial, sheep were fed alfalfa (Medicago sativa L.) silage diets supplemented with 0, 9, 18, or 27% sericea lespedeza (Lespedeza cuneate [Dumont de Courset] G. Don) (n = 4). In the second trial sheep were …


Resolution Of Lava Tubes With Ground Penetrating Radar: The Tubex Project, Sanaz Esmaeili, Sarah Kruse, Sajad Jazayeri, P. Whelley, E. Bell, J. Richardson, W. B. Garry, K. Young May 2020

Resolution Of Lava Tubes With Ground Penetrating Radar: The Tubex Project, Sanaz Esmaeili, Sarah Kruse, Sajad Jazayeri, P. Whelley, E. Bell, J. Richardson, W. B. Garry, K. Young

School of Geosciences Faculty and Staff Publications

Remote sensing surveys of the Moon and Mars show evidence of lava tubes, which are potential safe havens for human crews and their equipment. Ground penetrating radar (GPR) can be used to map tubes because the void/rock interface at tube ceilings and floors strongly reflects radar pulses. We have tested the capacity of GPR to sense lava tube geometry at Lava Beds National Monument in California, USA. GPR and detailed light detection and ranging (LiDAR) data are presented for two tubes: Skull Cave, with a few meters of overburden, diameter ~10–20 m, and a rubbly floor; and Valentine Cave, with …


Biogenic Silica And Organic Carbon Records In Zhoushan Coastal Sea Over The Past One Hundred Years And Their Environmental Indications, Hao Xu, Shangwei Jiang, Jialin Li, Ruiliang Pu, Jia Wang, Wanghai Jin, Longbin Sha, Dongling Li May 2020

Biogenic Silica And Organic Carbon Records In Zhoushan Coastal Sea Over The Past One Hundred Years And Their Environmental Indications, Hao Xu, Shangwei Jiang, Jialin Li, Ruiliang Pu, Jia Wang, Wanghai Jin, Longbin Sha, Dongling Li

School of Geosciences Faculty and Staff Publications

The influence of terrestrial and marine input has dramatically changed eutrophication in coastal seas over the past 100 years. In this study, Zhoushan coastal sea (ZCS) is taken as a study area. We studied ZCS as it is a sink of the temporal and spatial variation of primary productivity, dominant species of algae, and the variation of provenance in this area over the past 100 years. We performed analysis using three sediment cores and the carbon and silicon deposition records. The analysis results demonstrate that: (1) The primary productivity in the northern area of the ZCS close to the Yangtze …


Surface Deformation And Induced Seismicity Due To Fluid Injection And Oil And Gas Extraction In Western Texas, Fanghui Deng, Timothy H. Dixon, Surui Xie May 2020

Surface Deformation And Induced Seismicity Due To Fluid Injection And Oil And Gas Extraction In Western Texas, Fanghui Deng, Timothy H. Dixon, Surui Xie

School of Geosciences Faculty and Staff Publications

Texas is experiencing increasing seismicity, likely related to the oil and gas production process. We used satellite InSAR (Interferometric Synthetic Aperture Radar) to monitor surface deformation at three study sites in western Texas with similar geologic characteristics. The deformation data were compared to earthquake distribution, groundwater changes, volumes of produced and injected fluid, and calculated pore pressure change and Coulomb failure stress change to assess causes of deformation and seismicity. Site 1 experienced surface uplift due to fluid injection but no increase in seismicity. The average media properties were estimated based on the deformation using a poroelastic model. Site 2 …


Nanotextural And Nanochemical Constraints On The Role Of Heat In The Development Of Crystalline-Hosted, Silica-Rich Fault Mirrors In The Wasatch Fault Damage Zone, Utah, Usa, Leah M. Houser May 2020

Nanotextural And Nanochemical Constraints On The Role Of Heat In The Development Of Crystalline-Hosted, Silica-Rich Fault Mirrors In The Wasatch Fault Damage Zone, Utah, Usa, Leah M. Houser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Earthquakes occur on faults, or rock that has experienced displacement at depth. Experimental work on a range of rock types reveals that >90% of earthquake energy on fault surfaces is given off as heat. Heat weakens rock and promotes earthquake rupture propagation. Thin (<0.5mm), high-gloss, "polished", light-reflective exposed fault surfaces are called fault mirrors (FMs). Fault mirrors may record rapid thermal, textural, and chemical changes that occur during an earthquake event.

The Wasatch Mountains are a N-S trending mountain range in Northern Utah that are the backdrop for Salt Lake City, Provo, Ogden, and Brigham City. This mountain range is currently built by the active Wasatch fault, and includes the exposed Wasatch fault damage zone. Many segments of the Wasatch fault are overdue for a potentially catastrophic …


Sedimentary Dynamics And Water Quality In Floodplains Of The Lower Mississippi River Near Natchez, Mississippi, During The 2018 And 2019 Floods, Jansen Costello May 2020

Sedimentary Dynamics And Water Quality In Floodplains Of The Lower Mississippi River Near Natchez, Mississippi, During The 2018 And 2019 Floods, Jansen Costello

Master's Theses

The Lower Mississippi River (LMR) near Natchez, Mississippi, experienced intervals of major flooding during the 2018 and 2019 water years. While federal agencies sample sediment and water quality in the main LMR channel, little is known about sedimentary dynamics, water quality, and nutrient concentrations of the overbank water column within the embanked LMR floodplain. These data are needed to support ecological floodplain restoration efforts and provide context for downstream concerns including sediment delivery to coastal zones and hypoxia in the Gulf of Mexico.

This study monitored the overbank flood pulses and associated sediment deposition along the LMR embanked floodplain during …


The Biostratigraphy Of The Offshore Niger Delta During The Late Quaternary: Complexities And Progress Of Dating Techniques, Onema Adojoh, Fabienne Marret-Davies, Robert Duller, Peter Osterloff, Francisca Oboh-Ikuenobe, Malcolm Hart, Christopher Smart May 2020

The Biostratigraphy Of The Offshore Niger Delta During The Late Quaternary: Complexities And Progress Of Dating Techniques, Onema Adojoh, Fabienne Marret-Davies, Robert Duller, Peter Osterloff, Francisca Oboh-Ikuenobe, Malcolm Hart, Christopher Smart

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Late Quaternary marine sediments from the Niger Delta lacks an age model using conventional radiocarbon dating due to the rarity of calcareous macrofossils. The proprietary nature of material drilled by companies prospecting for hydrocarbons in the Niger Delta basin, and in the rare cases when samples are available for study as well as freshwater dilution from continental runoff have contributed to this dearth of knowledge. The availability of three shallow marine (∼3 m) gravity cores obtained from the eastern, central, and western parts of the Niger Delta provides the opportunity for biostratigraphy utilizing well-preserved marker species of planktonic foraminifera …


Paleoecology Of Columbian And Pygmy Mammoths In Southern Nevada And California: How Terminal Pleistocene Ecosystems Shaped Mammoths At The Individual, Population, And Community Level, Lauren Elizabeth Parry May 2020

Paleoecology Of Columbian And Pygmy Mammoths In Southern Nevada And California: How Terminal Pleistocene Ecosystems Shaped Mammoths At The Individual, Population, And Community Level, Lauren Elizabeth Parry

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this dissertation research is to examine the paleoecology of the Columbian mammoth (Mammuthus columbi) and the pygmy mammoth (M. exilis) on the individual, population, and community level, emphasizing factors internal to their ecosystem that may have contributed to their extinction. I focus specifically on mammoths from Southern Nevada and Southern California to add regional data to the complex and evolving study of North American mammoth paleoecology.

Chapter 2 documents the permitted excavation of a partial mammoth (Mammuthus sp.) between 2016-2018 from late Pleistocene groundwater-discharge deposits near Fairbanks Spring in the Amargosa Valley, Nevada. A preliminary radiocarbon date …


Controls On The Formation Of Microbially Induced Sedimentary Structures And Biotic Recovery In The Lower Triassic Of Arctic Canada, Paul B. Wignall, David P.G. Bond, Stephen E. Grasby, Sara B. Pruss, Jeffrey Peakall May 2020

Controls On The Formation Of Microbially Induced Sedimentary Structures And Biotic Recovery In The Lower Triassic Of Arctic Canada, Paul B. Wignall, David P.G. Bond, Stephen E. Grasby, Sara B. Pruss, Jeffrey Peakall

Geosciences: Faculty Publications

Microbially induced sedimentary structures (MISS) are reportedly widespread in the Early Triassic and their occurrence is attributed to either the extinction of marine grazers (allowing mat preservation) during the Permo-Triassic mass extinction or the suppression of grazing due to harsh, oxygenpoor conditions in its aftermath. Here we report on the abundant occurrence of MISS in the Lower Triassic Blind Fiord Formation of the Sverdrup Basin, Arctic Canada. Sedimentological analysis shows that mid-shelf settings were dominated by deposition from cohesive sand-mud flows that produced heterolithic, rippled sandstone facies that pass down dip into laminated siltstones and ultimately basinal mudrocks. The absence …


Nearshore Sedimentology Of Eroding Microtidal Estuaries: Bon Secour Bay, Alabama And Perdido Bay, Florida, Jennifer Simpson May 2020

Nearshore Sedimentology Of Eroding Microtidal Estuaries: Bon Secour Bay, Alabama And Perdido Bay, Florida, Jennifer Simpson

Master's Theses

Estuarine shorelines along the northern Gulf of Mexico are dynamic geologic settings that provide numerous ecological and economic benefits. By definition, estuaries are semi-enclosed bodies of water that receive sediment from two sources: (1) fluvial systems feeding into the estuary and (2) sediment transported by wave action and tidal currents from adjacent marine sources. Erosion of estuarine shorelines resulting from rising sea level, storm impact, and anthropogenic influence has been increasingly evident in the microtidal Gulf Coast over recent decades. This study collects quantitative and qualitative data to better understand sedimentary dynamics associated with contemporary estuarine shoreline erosion in Bon …


Infiltration Into Water-Repellent Sand: The Role Of Sorptivity, Rose Marie Shillito May 2020

Infiltration Into Water-Repellent Sand: The Role Of Sorptivity, Rose Marie Shillito

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soil water repellency (SWR) is believed to contribute to the increased potential for post-fire runoff and erosion. Currently, no quantitative method exists to account for SWR in physically-based runoff models. A physically-based model incorporating SWR (through the contact angle) in the infiltration parameter, sorptivity, was developed. The model was tested and verified with controlled laboratory tests on a fully characterized sand treated to create various degrees of SWR. The ability to create the wetting water characteristic curve for untreated and treated sand, appropriate for the infiltration process, was presented. Additionally, the ability to measure sorptivity with widely used infiltration tests …


An Evaluation Of Bank Storage At Lake Mead Reservoir In The Southwest United States, Jon Woodrow Wilson May 2020

An Evaluation Of Bank Storage At Lake Mead Reservoir In The Southwest United States, Jon Woodrow Wilson

UNLV Theses, Dissertations, Professional Papers, and Capstones

A water balance model is employed at Lake Mead to monitor and verify changing hydrology that affects total volume at the reservoir. Bank storage, which is defined as the volume of water captured in permeable lithologic layers subject to changes induced by contact and proximity to an open waterbody, is one component that is updated regularly and is based upon data and methods that were developed in the 1960’s from observations made within the first 30 years of the reservoir's maturation. Since this period, the reservoir has undergone further development and a current understanding of additional hydrologic affects to bank …


Analyzing The Effects Of Of Seasonal Land Cover And Precipitation On The Sediment Delivery Ratio Of An Agriculture Dominated Watershed., Jonah Liebman May 2020

Analyzing The Effects Of Of Seasonal Land Cover And Precipitation On The Sediment Delivery Ratio Of An Agriculture Dominated Watershed., Jonah Liebman

Electronic Theses and Dissertations

Soil erosion is of escalating importance as increasing population and climate change have put increasing pressures on agricultural food production. Vegetation and precipitation are two factors that control the amount of soil erosion extant within a region. Sediment delivery ratios (SDRs) assess the ratio of soil eroded from a watershed system that is permanently removed from the system through stream sediment discharge. Using 1) river discharge and sediment concentration data and 2) the Revised Universal Soil Loss Equation (RUSLE), this thesis analyzes fluctuations in monthly SDRs for an average hydroclimatological crop-harvest season for the Senachwine Creek watershed, IL. Through calculating …