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Articles 5221 - 5250 of 29938

Full-Text Articles in Geology

Mgrre_Thinsections_05_A_16, Mgrre Sep 2022

Mgrre_Thinsections_05_A_16, Mgrre

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No abstract provided.


Sediment Source Fingerprinting As An Aid To Large-Scale Landscape Conservation And Restoration: A Review For The Mississippi River Basin, Zhen Xu, Patrick Belmont, Janice Brahney, Allen C. Gellis Sep 2022

Sediment Source Fingerprinting As An Aid To Large-Scale Landscape Conservation And Restoration: A Review For The Mississippi River Basin, Zhen Xu, Patrick Belmont, Janice Brahney, Allen C. Gellis

United States Geological Survey: Staff Publications

Reliable quantitative information on sediment sources to rivers is critical to mitigate contamination and target conservation and restoration actions. However, for large-scale river basins, determination of the relative importance of sediment sources is complicated by spatiotemporal variability in erosional processes and sediment sources, heterogeneity in sediment transport and deposition, and a paucity of sediment monitoring data. Sediment source fingerprinting is an increasingly adopted field-based technique that identifies the nature and relative source contribution of sediment transported in waterways. Notably, sediment source fingerprinting provides information that is independent of other field, modeling, or remotely sensed techniques. However, the diversity in sampling, …


Mgrre_Thinsections_05_A_15, Mgrre Sep 2022

Mgrre_Thinsections_05_A_15, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_14, Mgrre Sep 2022

Mgrre_Thinsections_05_A_14, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_13, Mgrre Sep 2022

Mgrre_Thinsections_05_A_13, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_12, Mgrre Sep 2022

Mgrre_Thinsections_05_A_12, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_11, Mgrre Sep 2022

Mgrre_Thinsections_05_A_11, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_10, Mgrre Sep 2022

Mgrre_Thinsections_05_A_10, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_9, Mgrre Sep 2022

Mgrre_Thinsections_05_A_9, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_8, Mgrre Sep 2022

Mgrre_Thinsections_05_A_8, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_7, Mgrre Sep 2022

Mgrre_Thinsections_05_A_7, Mgrre

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No abstract provided.


Landslide Susceptibility Map Of Martin County, Kentucky, Matt M. Crawford, Hudson J. Koch, Jason M. Dortch, William C. Haneberg Sep 2022

Landslide Susceptibility Map Of Martin County, Kentucky, Matt M. Crawford, Hudson J. Koch, Jason M. Dortch, William C. Haneberg

Contract Reports--KGS

The purpose of this map is to identify landslide-prone areas in Martin County in order to provide the public, as well as local and state government agencies, with information about where landslides are likely to occur. This map represents geomorphic-based susceptibility modeling that focuses on physical slope characteristics and morphology, the quality of which is dependent on data accuracy and resolution of terrain models. The availability of high-resolution (5-ft digital elevation model) lidar derived datasets allows for the generation of terrain elevation derivatives such as hillshades, slope, aspect, curvature, and roughness, as well as identification of existing landslide deposits. These …


Revisiting 228Th As A Tool For Determining Sedimentation And Mass Accumulation Rates, Joseph J. Tamborski, Pinghe Cai, Meagan Eagle, Paul Henderson, Matthew A. Charette Sep 2022

Revisiting 228Th As A Tool For Determining Sedimentation And Mass Accumulation Rates, Joseph J. Tamborski, Pinghe Cai, Meagan Eagle, Paul Henderson, Matthew A. Charette

OES Faculty Publications

The use of 228Th has seen limited application for determining sedimentation and mass accumulation rates in coastal and marine environments. Recent analytical advances have enabled rapid, precise measurements of particle-bound 228Th using a radium delayed coincidence counting system (RaDeCC). Herein we review the 228Th cycle in the marine environment and revisit the historical use of 228Th as a tracer for determining sediment vertical accretion and mass accumulation rates in light of new measurement techniques. Case studies comparing accumulation rates from 228Th and 210Pb are presented for a micro-tidal salt marsh and a marginal sea …


A Demonstration Of A Simple Methodology Of Flood Prediction For A Coastal City Under Threat Of Sea Level Rise: The Case Of Norfolk, Va, Usa, Tal Ezer Sep 2022

A Demonstration Of A Simple Methodology Of Flood Prediction For A Coastal City Under Threat Of Sea Level Rise: The Case Of Norfolk, Va, Usa, Tal Ezer

CCPO Publications

Many coastal cities around the world are at risk of increased flooding due to sea level rise (SLR), so here a simple flood prediction method is demonstrated for one city at risk, Norfolk, VA, on the U.S. East Coast. The probability of future flooding is estimated by extending observed hourly water level for 1927–2021 into hourly estimates until 2100. Unlike most other flood prediction methods, the approach here does not use any predetermined probability distribution function of extreme events, and instead a random sampling of past data represents tides and storm surges. The probability of flooding for 3 different flood …


Mgrre_Thinsections_05_A_6, Mgrre Aug 2022

Mgrre_Thinsections_05_A_6, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_05_A_5, Mgrre Aug 2022

Mgrre_Thinsections_05_A_5, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_4, Mgrre Aug 2022

Mgrre_Thinsections_05_A_4, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_3, Mgrre Aug 2022

Mgrre_Thinsections_05_A_3, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_2, Mgrre Aug 2022

Mgrre_Thinsections_05_A_2, Mgrre

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No abstract provided.


Mgrre_Thinsections_05_A_1, Mgrre Aug 2022

Mgrre_Thinsections_05_A_1, Mgrre

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No abstract provided.


Compositionally And Density Stratified Igneous Terrain In Jezero Crater, Mars, Roger C. Wiens, Arya Udry, Olivier Beyssac, Cathy Quantin-Nataf, Nicolas Mangold, 80+ Authors Contributed To This Work Aug 2022

Compositionally And Density Stratified Igneous Terrain In Jezero Crater, Mars, Roger C. Wiens, Arya Udry, Olivier Beyssac, Cathy Quantin-Nataf, Nicolas Mangold, 80+ Authors Contributed To This Work

Geoscience Faculty Research

Before Perseverance, Jezero crater’s floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on Mars revealed a volcanic and intrusive terrain with compositional and density stratification. The dominant lithology along the traverse is basaltic, with plagioclase enrichment in stratigraphically higher locations. Stratigraphically lower, layered rocks are richer in normative pyroxene. The lowest observed unit has the highest inferred density and is olivine-rich with coarse (1.5 millimeters) euhedral, relatively unweathered grains, suggesting a cumulate origin. This is the first martian cumulate and shows similarities to martian meteorites, which …


The Art Of Landslides: How Stochastic Mass Wasting Shapes Topography And Influences Landscape Dynamics, Benjamin Campforts, Charles Shobe, Irina Overeem, Gregory Tucker Aug 2022

The Art Of Landslides: How Stochastic Mass Wasting Shapes Topography And Influences Landscape Dynamics, Benjamin Campforts, Charles Shobe, Irina Overeem, Gregory Tucker

Faculty & Staff Scholarship

Bedrock landslides shape topography and mobilize large volumes of sediment. Yet, interactions between landslide-produced sediment and fluvial systems that together govern large-scale landscape evolution are not well understood. To explain morphological patterns observed in steep, landslide-prone terrain, we explicitly model stochastic landsliding and associated sediment dynamics. The model accounts for several common landscape features such as slope frequency distributions, which include values in excess of regional stability limits, quasi-planar hillslopes decorated with straight, closely spaced channel-like features, and accumulation of sediment in valley networks rather than on hillslopes. Stochastic landsliding strongly affects the magnitude and timing of sediment supply to …


Seasonality Of Precipitation In The Southwestern United States During The Late Pleistocene Inferred From Stable Isotopes In Herbivore Tooth Enamel, Matthew J. Kohn, Kathleen B. Springer, Jeffrey S. Pigati, Linda M. Reynard, Amanda E. Drewicz, Justin Crevier, Eric Scott Aug 2022

Seasonality Of Precipitation In The Southwestern United States During The Late Pleistocene Inferred From Stable Isotopes In Herbivore Tooth Enamel, Matthew J. Kohn, Kathleen B. Springer, Jeffrey S. Pigati, Linda M. Reynard, Amanda E. Drewicz, Justin Crevier, Eric Scott

United States Geological Survey: Staff Publications

The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warmdry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the increased precipitation are debated. Increases in the proportions of C4/(C4+ C3) grasses in the diets of large grazers have been ascribed both to increases in summer precipitation and lower atmospheric CO2 levels. Here we present stable carbon and oxygen isotope data from tooth enamel of late Pleistocene herbivores recovered …


Microplastics In The Marine Environment And Deep-Sea Sediment Contamination: A Review, Elizabeth Sangiolo Aug 2022

Microplastics In The Marine Environment And Deep-Sea Sediment Contamination: A Review, Elizabeth Sangiolo

Honors Program Theses and Projects

This review discusses what microplastics are and how they are continuously impacting the marine environment, and ultimately, human life. Plastic has been the number one used material for decades for industrial and recreational purposes. Its cost effectiveness, durability, and lightness are what manufacturers and consumers desire most, making plastic the most abundant pollutant in the world. Understanding how plastic pollution is broken down into microplastics and how these fragmented pieces of waste are classified can help researchers identify ways to prevent the additional input of microplastics in the marine environment. These microscopic particles of debris have been sampled from deep-sea …


Collateral Damage: Anticoagulant Rodenticides Pose Threats To California Condors, Garth Herring, Collin A. Eagles-Smith, Rachel Wolstenholme, Alacia Welch, Chris West, Barnett A. Rattner Aug 2022

Collateral Damage: Anticoagulant Rodenticides Pose Threats To California Condors, Garth Herring, Collin A. Eagles-Smith, Rachel Wolstenholme, Alacia Welch, Chris West, Barnett A. Rattner

United States Geological Survey: Staff Publications

Anticoagulant rodenticides (ARs) are widespread environmental contaminants that pose risks to scavenging birds because they routinely occur within their prey and can cause secondary poisoning. However, little is known about AR exposure in one of the rarest avian scavengers in the world, the California condor (Gymnogyps californianus). We assessed AR exposure in California condors and surrogate turkey vultures (Cathartes aura) to gauge potential hazard to a proposed future condor flock by determining how application rate and environmental factors influence exposure. Additionally, we examined whether ARs might be correlated with prolonged blood clotting time and potential mortality …


Mgrre_Thinsections_Mgrre-108_5, Mgrre Aug 2022

Mgrre_Thinsections_Mgrre-108_5, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-108_3, Mgrre Aug 2022

Mgrre_Thinsections_Mgrre-108_3, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-108_1, Mgrre Aug 2022

Mgrre_Thinsections_Mgrre-108_1, Mgrre

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No abstract provided.


Mgrre_Thinsections_Mgrre-108_6, Mgrre Aug 2022

Mgrre_Thinsections_Mgrre-108_6, Mgrre

Thin Sections

No abstract provided.


Mgrre_Thinsections_Mgrre-108_8, Mgrre Aug 2022

Mgrre_Thinsections_Mgrre-108_8, Mgrre

Thin Sections

No abstract provided.