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2021

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Articles 15091 - 15120 of 16207

Full-Text Articles in Earth Sciences

Characterization And Delineation Of Potential Evaporite Geohazards Using Electrical Resistivity Methods Along Fm 2185, Culberson County, Texas, Lenora Diane Perkins May 2021

Characterization And Delineation Of Potential Evaporite Geohazards Using Electrical Resistivity Methods Along Fm 2185, Culberson County, Texas, Lenora Diane Perkins

Electronic Theses and Dissertations

Extensive karst development within the Delaware Basin of West Texas and southeastern New Mexico poses a significant geohazard threat to infrastructure. Dissolution of regional evaporite strata have led to manifestations of karst geohazard phenomena including sinkholes, subsidence features, and caves. The study area is located within the Gypsum Plain in Culberson County, Texas, and includes outcrops of Castile and Rustler strata that host gypsum karst geohazards. Land reconnaissance surveys conducted during the summer of 2019 documented numerous surficial manifestations of karst features proximal to Farm to Market Road 2185 (FM 2185). In combination with traditional survey techniques, electrical resistivity methods …


Spatial And Temporal Patterns Of River Incision And Terrace Deposition In Response To Climate And Tectonics In Southern Taiwan, Dominique M. Shore May 2021

Spatial And Temporal Patterns Of River Incision And Terrace Deposition In Response To Climate And Tectonics In Southern Taiwan, Dominique M. Shore

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Geologists often look at the Earth’s surface to understand the underlying processes that cause mountain formation. As tectonic forces drive uplift of Earth’s surface, processes of erosion transport sediment to lower elevations. Climate can play a large role in landscape formation as well as increased precipitation, accelerating rates of erosion. Rivers leave markers of landscape evolution through terrace landforms, former river floodplains that are left behind when rivers incise into a valley. To better understand landscape response to uplift, this research investigated the initial linkages between uplift, hillslope erosion (mass wasting) and river incision. At some point, it is thought …


Structural Re-Orientation Of Magmatic Fabrics And Layering In The Lower Oceanic Crust: Hole Gt1, Wadi Tayin Massif, Samail Ophiolite, Justin Guillot May 2021

Structural Re-Orientation Of Magmatic Fabrics And Layering In The Lower Oceanic Crust: Hole Gt1, Wadi Tayin Massif, Samail Ophiolite, Justin Guillot

Master's Theses

This thesis aims to re-orient borehole images of layered gabbros sampled beneath Hole GT1 in the Wadi Tayin massif of the Oman ophiolite by the Oman Drilling Project to better constrain models of crustal accretion. The gabbro glacier model proposes that crystallized basalt flows down and away from the crystallization site to form the lower crust while the sheeted sill model proposes that basaltic melt crystallizes at multiple levels in the crust through sills. Hole GT1 provides an unprecedented 400 m, 100% recovery, look at the lower oceanic crust. Cores lose their geographic orientation when drilled, requiring use of the …


Petrogenesis Of Hawaiian Lavas: Investigations Using Radiogenic And Non-Traditional Stable Isotopes, Christopher Defelice May 2021

Petrogenesis Of Hawaiian Lavas: Investigations Using Radiogenic And Non-Traditional Stable Isotopes, Christopher Defelice

UNLV Theses, Dissertations, Professional Papers, and Capstones

Earth’s mantle is the most voluminous part of the planet and is inaccessible to direct investigations. It is only possible to study it through indirect methods, such as the chemical makeup of erupted lavas. The Hawaiian Islands are thought to be the product of the mantle plume hypothesis, sometimes called a hot spot. Material from the Earth’s mantle is brought to the surface and erupted as magnesium rich lavas and form basalts. Hawaii is the longest lived active hot spot on Earth and makes it an ideal candidate for understanding the evolution of the Earth’s mantle and how lavas cool …


Extreme Event Reconstructions For The Upper Fraser River Basin, British Columbia, Canada, Inga K. Homfeld May 2021

Extreme Event Reconstructions For The Upper Fraser River Basin, British Columbia, Canada, Inga K. Homfeld

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spring freshets and summer droughts have recently worsened in the Fraser River Basin, British Columbia, Canada, with significant impacts to the keystone Pacific salmon populations, the food and economic sovereignty of over eighty First Nations, and the western Canadian economy. These extreme events present a potential risk since, unlike many large and less hydroclimatically-complex and/or empounded watersheds, the Fraser River Basin is susceptible to a combination of unregulated spring freshet and summer drought events even within the same year. A major limitation for understanding past and future extreme event risk in the Fraser River Basin is that observational streamflow datasets …


Chronicling Magma Transit Beneath Hawaiian Volcanoes: Every Isotope A Word, Every Crystal A Story, Jonathan Pinko May 2021

Chronicling Magma Transit Beneath Hawaiian Volcanoes: Every Isotope A Word, Every Crystal A Story, Jonathan Pinko

UNLV Theses, Dissertations, Professional Papers, and Capstones

At many oceanic volcanoes, such as Hawaii, mantle-derived magmas migrate to crustal level magma chambers, where they accumulate before eruption. Understanding the magma chamber residence times, or the time gaps between the arrivals of new magmas and eruptions, is important in volcanic hazard mitigation. Here I apply iron and magnesium isotope effects in olivines to constrain these times at Hawaiian volcanoes. Combined with published data, I present bulk ?56Fe (-1.706 to 0.489) and ?26Mg (-0.400 to 0.356) in 108 Hawaiian olivines erupted from the pre-shield, shield, and post-shield stages. The Hawaiian olivine ?56Fe and ?26Mg represent the largest Fe-Mg isotope …


Prograde Metamorphism And Upper-Crustal Cooling In The Northern Panamint Range, California: New Insights Into The Jurassic And Mid-Cretaceous Evolution Of The Southern Sevier Fold-Thrust Belt, Elijah A. Turner May 2021

Prograde Metamorphism And Upper-Crustal Cooling In The Northern Panamint Range, California: New Insights Into The Jurassic And Mid-Cretaceous Evolution Of The Southern Sevier Fold-Thrust Belt, Elijah A. Turner

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Jurassic-Cretaceous southern Sevier fold-thrust belt, which experiences changes in orientation and structural style as it approaches intersection with the Mesozoic continental arc, has been pervasively overprinted by Neogene-Quaternary faulting, rendering its evolution enigmatic. Raman spectroscopy of carbonaceous material (RSCM) thermometry data from 14 samples and zircon (U-Th)/He (ZHe) thermochronology data from 23 samples collected in the northern Panamint Range illuminate the history of metamorphism and upper-crustal cooling associated with this belt of shortening structures. Best estimate peak temperatures derived from RSCM thermometry increase from 166 ± 19°C at 2.5 km structural depth (measured from the top of the exposed …


Using Low-Flow Sampling Data To Estimate Hydraulic Conductivity In Aquifers, Joy Kiefer May 2021

Using Low-Flow Sampling Data To Estimate Hydraulic Conductivity In Aquifers, Joy Kiefer

Masters Theses

Hydrogeologists sample wells to test aquifer water quality and use slug tests to estimate aquifer permeability. Robbins et al. (2009) proposed a more efficient way to obtain the goals of the two tests—the use of low-flow sampling and the use of the resulting flow rate and drawdown data to estimate aquifer hydraulic conductivity (K). The Robbins et al. method calculates K by using the slope of the best fit line from the graph of flow rate vs. drawdown for all low-flow pumping data collected at a well. When the method was applied to low-flow data from four Kalamazoo, MI, it …


Taphonomy Of Late Jurassic (Tithonian) Morrison Formation Apatosaurus Sp. Vertebrae Found Associated With Teeth From Allosaurus Sp. And Ceratosaurus Sp., And Body Size Extrapolation From The Associated Theropod Teeth., Greg C. Agyan May 2021

Taphonomy Of Late Jurassic (Tithonian) Morrison Formation Apatosaurus Sp. Vertebrae Found Associated With Teeth From Allosaurus Sp. And Ceratosaurus Sp., And Body Size Extrapolation From The Associated Theropod Teeth., Greg C. Agyan

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

An Apatosaurus sp. locality from Dinosaur National Monument designated DNM-15 was excavated in 1985, and associated with two Allosaurus teeth and one Ceratosaurus tooth that were near one of the caudal vertebrae. The Ceratosaurus tooth was buried between an overlying rib and that same caudal vertebra. The caudal vertebrae of the DNM-15 Apatosaurus were intact and articulated, but the anterior skeleton was mostly absent, with a row of articulated sacral vertebrae in close association with a femur. Two other Allosaurus teeth were reported near the preserved ilium of the Apatosaurus, but they could not be located in the collections. …


Effect Of Abiotic Factors On Enzyme Activity In Brownfield Soils, Diane Hagmann May 2021

Effect Of Abiotic Factors On Enzyme Activity In Brownfield Soils, Diane Hagmann

Theses, Dissertations and Culminating Projects

Several factors can influence soil function, including biotic and abiotic. Biotic factors are those that are living, like microorganisms. Abiotic factors are those that are non-living, and include heavy metals, organic contaminants, pH, and nutrients. Liberty State Park in Jersey City (N.J., U.S.A), is a 100-ha brownfield was once a major rail yard that was restricted public access in 1969. The site without any intervention of humans grew a forest. The primary objective of this dissertation is to understand the impacts of both inorganic and organic contaminants on soil function in addition to provide strategies that can override the negative …


Upstream Propagation Of Sea-Level Signals In Fluvio-Deltaic Environments : Time-Lags, And The Dynamics Of The Fluvial Surface, Madeline Pianta Kollegger May 2021

Upstream Propagation Of Sea-Level Signals In Fluvio-Deltaic Environments : Time-Lags, And The Dynamics Of The Fluvial Surface, Madeline Pianta Kollegger

Theses, Dissertations and Culminating Projects

The sedimentary record of fluvio-deltaic environments holds clues to past climate and sea level change. Although theories for stratigraphic interpretation generally rely upon the assumption that the fluvial surface responds uniformly to sea level changes, recent theoretical work suggests that changes in the relief and concavity of the fluvial surface can influence the propagation of sea level information upstream, and result in geologically long-lived lags in the system response. We test this theoretical result using measurements from an evolving experimental delta subject to sea-level cycles. As predicted by the theoretical results, during sea-level fall the relief increases and the fluvial …


Starter Nitrogen Source And Preflood Nitrogen Rate Effects On Rice Grown On Clay Soils, Linda Rachelle Martin May 2021

Starter Nitrogen Source And Preflood Nitrogen Rate Effects On Rice Grown On Clay Soils, Linda Rachelle Martin

Graduate Theses and Dissertations

Seedling rice (Oryza sativa L.) grown on clayey-textured soils generally develops slowly as compared to loamy-textured soils. Our research examined the effects of starter-N source and preflood-N rates on canopy closure, total aboveground N uptake, and grain yield of rice grown on clayey-textured soils. Eleven field trials were established in Arkansas and Mississippi including five trials with a hybrid cultivar and six trials using a pure-line cultivar. Starter-N sources included no starter-N (NONE), ammonium sulfate (AMS), diammonium phosphate (DAP), and urea (UREA) applied at 24 kg N ha-1 at the rice 2-leaf stage and five preflood-N rates ranging from 0-224 …


Carbon-Isotope Chemostratigraphy And Fluvial Sedimentology Of The Moenave Formation, Utah, Jordan Oefinger May 2021

Carbon-Isotope Chemostratigraphy And Fluvial Sedimentology Of The Moenave Formation, Utah, Jordan Oefinger

Graduate Theses and Dissertations

The end Triassic extinction (ETE) is one of the largest mass extinction events of the Phanerozoic, and it has been hypothesized that this event, as well as the Triassic-Jurassic (TJ) boundary, are preserved within the Moenave Formation of the Colorado Plateau. Identification of this boundary within southwest Utah sections of the Colorado Plateau region is critical for better understanding the relationship between climate change and the ETE in terrestrial, low latitude paleoenvironments. The Moenave Formation is well exposed in Blacks Canyon of Zion National Park and in the nearby Warner Valley, where detailed sedimentologic observations and carbon isotope sampling have …


Donnelly River Model Review, Justin Hughes May 2021

Donnelly River Model Review, Justin Hughes

Natural resources commissioned reports

The Donnelly River Model was prepared for the Department of Water and Environment Regulation (DWER) by an external consultant (Hydrology and Risk Consultants) in 2018. The purpose of this model was largely to evaluate the feasibility of a proposed irrigation development centred on diversions from the Middle Donnelly near Chappel's Bridge into a reservoir in the nearby Record Brook catchment. As a part of the model build and reporting process, the HARC (2018) report was reviewed by Ecological Australia (2018) against the model specifications. ECL concluded that the model was "fit for purpose", but made many recommendations. Since re­port release, …


Small-Scale Resuspension And Redistribution Of Surface Sediments In The Northeast Gulf Of Mexico, Austin Harris May 2021

Small-Scale Resuspension And Redistribution Of Surface Sediments In The Northeast Gulf Of Mexico, Austin Harris

Master's Theses

Following the release of ~4.9 million barrels of oil into the Gulf of Mexico from the Macondo wellhead, a vast area of the seafloor contained recently deposited marine sediments contaminated by the oil spill. The initial deposition of these contaminated marine sediments was likely not the end of the journey for the particles. Downslope gravitational processes and events of increased current speed in the deep ocean setting can result in recently deposited sediments to resuspend and be moved laterally with the current flow, increasing the area effected by the oil spill. Erosion experiments performed in a closed-loop resuspension flume were …


The Biggest Snowball Fight In Earth History: Stratigraphy, Facies Analysis, And Geochronology Of The Pocatello Formation, Matthew W. Ellison May 2021

The Biggest Snowball Fight In Earth History: Stratigraphy, Facies Analysis, And Geochronology Of The Pocatello Formation, Matthew W. Ellison

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Snowball Earth Hypothesis details a time in Earth’s history (the Cryogenian period) where the entire planet was encapsulated by kilometer thick ice sheets for two, multi-million-year glaciations. The first, known as the Sturtian, lasted from 717 – 660 million years ago while the second, known as the Marinoan, lasted form approximately 650 – 635 million years ago. Snowball Earth was caused by a few processes that sort of built upon each other: Rodinia began splitting apart ~740 million years ago which allowed for increased rates of silicate weathering. High rates of silicate weathering resulted in CO2 drawdown which …


A Comparison Of The Localized Aviation Mos Program (Lamp) And Terminal Aerodrome Forecast (Taf) Accuracy For General Aviation, Douglas D. Boyd, Thomas A. Guinn Apr 2021

A Comparison Of The Localized Aviation Mos Program (Lamp) And Terminal Aerodrome Forecast (Taf) Accuracy For General Aviation, Douglas D. Boyd, Thomas A. Guinn

Journal of Aviation Technology and Engineering

Background. For general aviation (GA) pilots, operations in instrument meteorological conditions (IMC) carry an elevated risk of a fatal accident. As to whether a general aviation flight can be safely undertaken, aerodrome-specific forecasts (TAF, LAMP) provide guidance. Although LAMP forecasts are more common for GA-frequented aerodromes, nevertheless, the FAA recommends that for such aerodromes (and for which a TAF is not issued) the airman uses the TAF generated for the geographically closest airport for pre-flight weather evaluation. Herein, for non-TAF-issuing airports, the LAMP (sLAMP) predictive accuracy for visual (VFR) and instrument (IFR) flight rules flight category was determined.

Method. sLAMP …


Effects Of Differences In Cell Wall Biochemistry On The Microbial Decomposition Of Sphagnum (Peat Moss), Alexis Koehl, Christian Lundy, Trevor Hile, Erik Schoonover Apr 2021

Effects Of Differences In Cell Wall Biochemistry On The Microbial Decomposition Of Sphagnum (Peat Moss), Alexis Koehl, Christian Lundy, Trevor Hile, Erik Schoonover

20th Annual Celebration of Undergraduate Research and Creative Activity (2021)

Globally, peatlands store twice as much carbon as there is in the atmosphere as CO2. As average global temperatures continue to rise, the growth or decay of these carbon stores will play an important feedback for future climate change. This study examined the mechanisms behind the rate of decomposition in Sphagnum mosses, specifically the differences in cell wall chemistry between species. We hypothesized that mosses from different microtopographies will differ in rate of decomposition, as previous studies have shown that hummock mosses have higher concentrations of recalcitrant structural carbohydrates in their cell walls compared to hollow mosses. The …


Polarimetric Radar Characteristics Of Tornadogenesis Failure In Supercell Thunderstorms, Matthew S. Van Den Broeke Apr 2021

Polarimetric Radar Characteristics Of Tornadogenesis Failure In Supercell Thunderstorms, Matthew S. Van Den Broeke

Department of Earth and Atmospheric Sciences: Faculty Publications

Many nontornadic supercell storms have times when they appear to be moving toward tornadogenesis, including the development of a strong low-level vortex, but never end up producing a tornado. These tornadogenesis failure (TGF) episodes can be a substantial challenge to operational meteorologists. In this study, a sample of 32 pre-tornadic and 36 pre-TGF supercells is examined in the 30 min pre-tornadogenesis or pre-TGF period to explore the feasibility of using polarimetric radar metrics to highlight storms with larger tornadogenesis potential in the near-term. Overall the results indicate few strong distinguishers of pre-tornadic storms. Differential reflectivity (ZDR) arc size …


The Flowering Dynamics And Seedset Of Cichorium Intybus L. Cv. Puna, Yongfeng Han, Chengbin Tang, Mouqiong Apr 2021

The Flowering Dynamics And Seedset Of Cichorium Intybus L. Cv. Puna, Yongfeng Han, Chengbin Tang, Mouqiong

IGC Proceedings (1977-2023)

No abstract provided.


The Effects Of Time Of Application Of Nitrogen On Seed Yield, Efficiency Of N Fertilizer Use And Apparent N Fertilizer Recovery Of Russian Wildrye [Psathyrostachys Juncea (Fisch.) Nevski], Jianguo Han, Yunwen Wang, Shengquan Jiang, Bo Liu Apr 2021

The Effects Of Time Of Application Of Nitrogen On Seed Yield, Efficiency Of N Fertilizer Use And Apparent N Fertilizer Recovery Of Russian Wildrye [Psathyrostachys Juncea (Fisch.) Nevski], Jianguo Han, Yunwen Wang, Shengquan Jiang, Bo Liu

IGC Proceedings (1977-2023)

No abstract provided.


Seed Yield Formation Of Festulolium And Lolium X Boucheanum Under Climatic Condition Of Latvia, Iveta Gutmane, Aleksandr Adamovich Apr 2021

Seed Yield Formation Of Festulolium And Lolium X Boucheanum Under Climatic Condition Of Latvia, Iveta Gutmane, Aleksandr Adamovich

IGC Proceedings (1977-2023)

No abstract provided.


Callus Induction And Plant Regeneration Of Poa Pratensis 'Nasu' Seeds Carried By China Recoverable Satellite Shijian‐8, Yinghua Guo, Lei Han, Guansheng Ju, Zhenyuan Sun Apr 2021

Callus Induction And Plant Regeneration Of Poa Pratensis 'Nasu' Seeds Carried By China Recoverable Satellite Shijian‐8, Yinghua Guo, Lei Han, Guansheng Ju, Zhenyuan Sun

IGC Proceedings (1977-2023)

No abstract provided.


Multi-Criteria Analysis For Mapping Susceptibility To Iron Formation Caves Development In The Gandarela Mountain Range (Mg), Southeast Brazil, Iraydes Tálita Nola, Luis Almeida Bacellar Apr 2021

Multi-Criteria Analysis For Mapping Susceptibility To Iron Formation Caves Development In The Gandarela Mountain Range (Mg), Southeast Brazil, Iraydes Tálita Nola, Luis Almeida Bacellar

International Journal of Speleology

In tropical regions, abundant in iron-rich geological materials, caves that are genetically and geographically associated with exploitable mineral deposits may develop. These caves have speleological relevance and are environmentally and legally protected in Brazil. Thus, for better planning of exploitation and environmental licensing, it is necessary to study the genesis and development of the iron formation caves seeking to preserve them without impeding the advancement of mining. This subject is complex, rarely studied, and few are the knowledges on alternatives to predict the occurrence of these caves. This gap justifies the development of research and products capable of assisting decision-makers, …


Biis: The Last British Ice Sheet, A Review Of The Most Recent Major Glaciation Of Great Britain And Ireland, Benediktas Gaskevicius Apr 2021

Biis: The Last British Ice Sheet, A Review Of The Most Recent Major Glaciation Of Great Britain And Ireland, Benediktas Gaskevicius

Honors College Theses

The British Irish Ice Sheet was a substantial ice mass covering the British Isles during the most recent glaciation that ended around 11,700 years ago. Oftentimes referred to as the BIIS, it is subdivided into two sections, a western and eastern side that covered Great Britain and Ireland, with the Irish basin in the middle. Some notable areas of study around Great Britain and Ireland include the ’Bizzle’ in Northern England, which was transformed by the effects of the eastern margin of the BIIS, the Carstair Kames in Scotland, a locality known internationally for its esker system, The Minch region …


Tannin Contents Of Sainfoin (Onobrycyhis Viciifolia Scop) Grown With Or Without Irrigation And Harvested At Different Growth Stages, Y. Wang, T. A. Mcallister, S. N. Acharya, K. H. Ominski, D. O. Krause Apr 2021

Tannin Contents Of Sainfoin (Onobrycyhis Viciifolia Scop) Grown With Or Without Irrigation And Harvested At Different Growth Stages, Y. Wang, T. A. Mcallister, S. N. Acharya, K. H. Ominski, D. O. Krause

IGC Proceedings (1977-2023)

No abstract provided.


Implications Of Excess Nitrogen For Intake, Diet Choice And Production Of Sheep Fed Temperate Pastures, Garry C. Waghorn, G. P. Cosgrove Apr 2021

Implications Of Excess Nitrogen For Intake, Diet Choice And Production Of Sheep Fed Temperate Pastures, Garry C. Waghorn, G. P. Cosgrove

IGC Proceedings (1977-2023)

No abstract provided.


Dynamic Topography Of The St. Francois Mountains, Joshua Carpenter Apr 2021

Dynamic Topography Of The St. Francois Mountains, Joshua Carpenter

Undergraduate Research Conference at Missouri S&T

The purpose of this research project was to search for evidence of relict topographic surfaces in the St. Francois Mountains that preserve a history of regional and/or global forces. To accomplish this, topographic cross-sections were taken in Google Earth to examine changes in the region's topography with focus towards the following features: sub-horizontal surfaces, knickpoints, and valley floors. Elevation data was then collected and plotted in Excel. This revealed sub-horizontal surfaces between elevations of ~1780-1545 ft; knickpoints between ~1700-900 ft; and valley floors at ~1470-1350 ft. and ~1200-900 ft. The sub-horizontal surfaces are interpreted as relict peneplains preserved during periods …


Sample Preparation Affects Non Structural Carbohydrates In Alfalfa, Gaëtan F. Tremblay, Annick Bertrand, Yves Castonguay, Gilles Bélanger, Sophie Pelletier, Réal Michaud Apr 2021

Sample Preparation Affects Non Structural Carbohydrates In Alfalfa, Gaëtan F. Tremblay, Annick Bertrand, Yves Castonguay, Gilles Bélanger, Sophie Pelletier, Réal Michaud

IGC Proceedings (1977-2023)

No abstract provided.


Nitrogen Intake And Utilisation Pattern In The Digestive Tract Of Sheep Grazing Four Subtropical Foggages, Willem A. Van Niekerk, Abubeker Hassen Apr 2021

Nitrogen Intake And Utilisation Pattern In The Digestive Tract Of Sheep Grazing Four Subtropical Foggages, Willem A. Van Niekerk, Abubeker Hassen

IGC Proceedings (1977-2023)

No abstract provided.