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Articles 23071 - 23100 of 29957

Full-Text Articles in Geology

Mapping Marginal Croplands Suitable For Cellulosic Feedstock Crops In The Great Plains, United States, Yingxin Gu, Bruce K. Wylie Jan 2016

Mapping Marginal Croplands Suitable For Cellulosic Feedstock Crops In The Great Plains, United States, Yingxin Gu, Bruce K. Wylie

United States Geological Survey: Staff Publications

Growing cellulosic feedstock crops (e.g., switchgrass) for biofuel is more environmentally sustainable than cornbased ethanol. Specifically, this practice can reduce soil erosion and water quality impairment from pesticides and fertilizer, improve ecosystem services and sustainability (e.g., serve as carbon sinks), and minimize impacts on global food supplies. The main goal of this study was to identify high-risk marginal croplands that are potentially suitable for growing cellulosic feedstock crops (e.g., switchgrass) in the US Great Plains (GP). Satellitederived growing season Normalized Difference Vegetation Index, a switchgrass biomass productivity map obtained from a previous study, US Geological Survey (USGS) irrigation and crop …


Evaluating Methods To Establish Habitat Suitability Criteria: A Case Study In The Upper Delaware River Basin, Usa, H. S. Galbraith, C. J. Blakeslee, J. C. Cole, C. A. Talbert, K. O. Maloney Jan 2016

Evaluating Methods To Establish Habitat Suitability Criteria: A Case Study In The Upper Delaware River Basin, Usa, H. S. Galbraith, C. J. Blakeslee, J. C. Cole, C. A. Talbert, K. O. Maloney

United States Geological Survey: Staff Publications

Defining habitat suitability criteria (HSC) of aquatic biota can be a key component to environmental flow science. HSC can be developed through numerous methods; however, few studies have evaluated the consistency of HSC developed by different methodologies. We directly compared HSC for depth and velocity developed by the Delphi method (expert opinion) and by two primary literature meta-analyses (literature- derived range and interquartile range) to assess whether these independent methods produce analogous criteria for multiple species (rainbow trout, brown trout, American shad, and shallow fast guild) and life stages. We further evaluated how these two independently developed HSC affect calculations …


Evaluating Land Cover Influences On Model Uncertainties—A Case Study Of Cropland Carbon Dynamics In The Mid-Continent Intensive Campaign Region, Zhengpeng Li, Shuguang Liu, Xuesong Zhang, Tristram O. West, Stephen M. Ogle, Naijun Zhou Jan 2016

Evaluating Land Cover Influences On Model Uncertainties—A Case Study Of Cropland Carbon Dynamics In The Mid-Continent Intensive Campaign Region, Zhengpeng Li, Shuguang Liu, Xuesong Zhang, Tristram O. West, Stephen M. Ogle, Naijun Zhou

United States Geological Survey: Staff Publications

tQuantifying spatial and temporal patterns of carbon sources and sinks and their uncertainties acrossagriculture-dominated areas remains challenging for understanding regional carbon cycles. Character-istics of local land cover inputs could impact the regional carbon estimates but the effect has not beenfully evaluated in the past. Within the North American Carbon Program Mid-Continent Intensive (MCI)Campaign, three models were developed to estimate carbon fluxes on croplands: an inventory-basedmodel, the Environmental Policy Integrated Climate (EPIC) model, and the General Ensemble biogeo-chemical Modeling System (GEMS) model. They all provided estimates of three major carbon fluxes oncropland: net primary production (NPP), net ecosystem production (NEP), and …


Processes Contributing To Resilience Of Coastal Wetlands To Sea-Level Rise, Camille L. Stagg, Ken W. Krauss, Donald R. Cahoon, Nicole Cormier, William H. Conner, Christopher M. Swarzenski Jan 2016

Processes Contributing To Resilience Of Coastal Wetlands To Sea-Level Rise, Camille L. Stagg, Ken W. Krauss, Donald R. Cahoon, Nicole Cormier, William H. Conner, Christopher M. Swarzenski

United States Geological Survey: Staff Publications

The objectives of this study were to identify processes that contribute to resilience of coastal wetlands subject to rising sea levels and to determine whether the relative contribution of these processes varies across different wetland community types. We assessed the resilience of wetlands to sea-level rise along a transitional gradient from tidal freshwater forested wetland (TFFW) to marsh by measuring processes controlling wetland elevation. We found that, over 5 years of measurement, TFFWs were resilient, although some marginally, and oligohaline marshes exhibited robust resilience to sea-level rise. We identified fundamental differences in how resilience is maintained across wetland community types, …


Conserving California Condors In The 1980s, Noel F.R. Snyder Jan 2016

Conserving California Condors In The 1980s, Noel F.R. Snyder

United States Geological Survey: Staff Publications

By the late 1970s, the California condor (Gymnogyps californianus) was in serious trouble, with probably no more than about 30 birds left in existence, all in a mountainous region just north of Los Angeles that is vegetated mainly in chaparral and grasslands. All estimates of population size and trends offered since the early condor studies by Carl Koford in the 1930s and 1940s indicated a continuing decline toward extinction, and it appeared that few years were left before the species would be gone (see Koford, 1953; Wilbur, 1978). Evidently, the conservation steps that had been taken, including the …


Patuxent’S American Black Duck Studies From Chesapeake Bay To Maine And Beyond, Jerry R. Longcore Jan 2016

Patuxent’S American Black Duck Studies From Chesapeake Bay To Maine And Beyond, Jerry R. Longcore

United States Geological Survey: Staff Publications

The information in this chapter draws on published literature and unpublished reports written by staff members of the U.S. Geological Survey, Patuxent Wildlife Research Center (Patuxent), during its 75-year history. Reports by Bureau of Biological Survey (Biological Survey) and U.S. Fish and Wildlife Service (USFWS) personnel are included because the research entity currently known as Patuxent was formerly administered by these agencies. Some of the cited reports were prepared by USFWS scientists while they were not working at Patuxent. Literature resulting from work at other Federal and State agencies and private and academic institutions that influenced research at Patuxent on …


The Migratory Bird And Habitat Research Laboratory And The Accelerated Research Program, Richard A. Coon Jan 2016

The Migratory Bird And Habitat Research Laboratory And The Accelerated Research Program, Richard A. Coon

United States Geological Survey: Staff Publications

The Patuxent Wildlife Research Center (Patuxent) housed two important programs that were not supervised through the office of the Director of Patuxent during the 1960s and 1970s. Although they received administrative support from Patuxent, they were supervised from the U.S. Fish and Wildlife Service (USFWS) headquarters in Washington, D.C. One, the Migratory Bird Populations Station (MBPS), was established in 1961; the other, the Migratory Bird and Habitat Research Laboratory (MBHRL), was established in 1972 (Perry, 2004). This chapter briefly discusses MBPS and how some of its functions were transferred to MBHRL when this new laboratory was created.


Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove Jan 2016

Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove

United States Geological Survey: Staff Publications

Through laboratory and field studies, the utility of amino acid compound-specific nitrogen isotope analysis (AA-CSIA) in avian studies is investigated. Captive American kestrels (Falco sparverius) were fed an isotopically characterized diet and patterns in δ15N values of amino acids (AAs) were compared to those in their tissues (muscle and red blood cells) and food. Based upon nitrogen isotope discrimination between diet and kestrel tissues, AAs could mostly be categorized as source AAs (retaining baseline δ15N values) and trophic AAs (showing 15N enrichment). Trophic discrimination factors based upon the source (phenylalanine, Phe) and trophic (glutamic acid, Glu) AAs were 4.1 (muscle) …


Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen Jan 2016

Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen

United States Geological Survey: Staff Publications

The response of ecosystems to climate warming is likely to include threshold events when small changes in key environmental drivers produce large changes in an ecosystem. Wetlands of the Prairie Pothole Region (PPR) are especially sensitive to climate variability, yet the possibility that functional changes may occur more rapidly with warming than expected has not been examined or modeled. The productivity and biodiversity of these wetlands are strongly controlled by the speed and completeness of a vegetation cover cycle driven by the wet and dry extremes of climate. Two thresholds involving duration and depth of standing water must be exceeded …


Pranked By Audubon: Constantine S. Rafinesque’S Description Of John James Audubon’S Imaginary Kentucky Mammals, Neal Woodman Jan 2016

Pranked By Audubon: Constantine S. Rafinesque’S Description Of John James Audubon’S Imaginary Kentucky Mammals, Neal Woodman

United States Geological Survey: Staff Publications

The North American naturalist Constantine S. Rafinesque spent much of the year 1818 engaged in a solo journey down the Ohio River Valley to explore parts of what was then the western United States. Along the way, he visited a number of fellow naturalists, and he spent more than a week at the Henderson, Kentucky, home of artist and ornithologist John James Audubon. During the succeeding two years, Rafinesque published descriptions of new species that resulted from his expedition, including eleven species of fishes that eventually proved to have been invented by Audubon as a prank on the credulous naturalist. …


Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove Jan 2016

Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove

United States Geological Survey: Staff Publications

Through laboratory and field studies, the utility of amino acid compound-specific nitrogen isotope analysis (AA-CSIA) in avian studies is investigated. Captive American kestrels (Falco sparverius) were fed an isotopically characterized diet and patterns in δ15N values of amino acids (AAs) were compared to those in their tissues (muscle and red blood cells) and food. Based upon nitrogen isotope discrimination between diet and kestrel tissues, AAs could mostly be categorized as source AAs (retaining baseline δ15N values) and trophic AAs (showing 15N enrichment). Trophic discrimination factors based upon the source (phenylalanine, Phe) and trophic (glutamic acid, Glu) AAs were 4.1 (muscle) …


Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen Jan 2016

Non-Linear Responses Of Glaciated Prairie Wetlands To Climate Warming, W. Carter Johnson, Brett Werner, Glenn R. Guntenspergen

United States Geological Survey: Staff Publications

The response of ecosystems to climate warming is likely to include threshold events when small changes in key environmental drivers produce large changes in an ecosystem. Wetlands of the Prairie Pothole Region (PPR) are especially sensitive to climate variability, yet the possibility that functional changes may occur more rapidly with warming than expected has not been examined or modeled. The productivity and biodiversity of these wetlands are strongly controlled by the speed and completeness of a vegetation cover cycle driven by the wet and dry extremes of climate. Two thresholds involving duration and depth of standing water must be exceeded …


Pranked By Audubon: Constantine S. Rafinesque’S Description Of John James Audubon’S Imaginary Kentucky Mammals, Neal Woodman Jan 2016

Pranked By Audubon: Constantine S. Rafinesque’S Description Of John James Audubon’S Imaginary Kentucky Mammals, Neal Woodman

United States Geological Survey: Staff Publications

The North American naturalist Constantine S. Rafinesque spent much of the year 1818 engaged in a solo journey down the Ohio River Valley to explore parts of what was then the western United States. Along the way, he visited a number of fellow naturalists, and he spent more than a week at the Henderson, Kentucky, home of artist and ornithologist John James Audubon. During the succeeding two years, Rafinesque published descriptions of new species that resulted from his expedition, including eleven species of fishes that eventually proved to have been invented by Audubon as a prank on the credulous naturalist. …


Modern Foraminiferal Assemblages Of The Denmark Strait, Laura Larocca Jan 2016

Modern Foraminiferal Assemblages Of The Denmark Strait, Laura Larocca

Dissertations and Theses

Foraminifera occupy a geological range from the early Cambrian to the present day. Their well preserved shells, high relative abundance, and short response time to changing environmental conditions make foraminifera ideal proxies for environmental change. Benthic foraminifera are a valuable but poorly understood paleobiological proxy for the reconstruction of environmental conditions on continental shelves occupied by arctic and subarctic waters. This study identifies, examines, and quantifies calcareous benthic foraminiferal faunas from a sediment core taken from the Denmark Strait. Our analysis of three-thousand individuals from ten discrete samples aim to provide a better understanding of the modern patterns of foraminiferal …


Analyzing Evapotranspiration In The Tropical Montane Cloud Forest At Sierra De Bahoruco, Dominican Republic, Emmanuel Rodriguez-Gonzalez Jan 2016

Analyzing Evapotranspiration In The Tropical Montane Cloud Forest At Sierra De Bahoruco, Dominican Republic, Emmanuel Rodriguez-Gonzalez

Dissertations and Theses

Lake Enriquillo is located in the southwestern extreme of Dominican Republic and has been experiencing a rapid expansion in surface area, along with other water bodies in the same region, since 2004 causing major flooding to the surrounding agricultural and cattle-raising lands, infrastructure and communities. Understanding why the lake is expanding at such rapid rate and accurately forecast how they will behave in the future is the main goal of The Hispaniola Lakes Project. The purpose of this project is to investigate the effects that hydrometeorological drivers are having on the forested areas located in Sierra de Bahoruco, which is …


3d Structural And Stratigraphic Architecture Of The Northwest Santa Barbara Basin And Implications For Submarine Landslide Generation, Alexis Wright Jan 2016

3d Structural And Stratigraphic Architecture Of The Northwest Santa Barbara Basin And Implications For Submarine Landslide Generation, Alexis Wright

Dissertations and Theses

Multiple submarine landslides have been previously documented on the north flank of the Santa Barbara Channel, and such failures are considered to be capable of generating local tsunamis hazards to the Santa Barbara region. 2D seismic-reflection datasets provide a general view of regional framework geology, including faulting and folding associated with north-south compression. However, better understanding of the relationships between faults, folds, stratigraphic architecture, and submarine landslides can be obtained with 3D seismic datasets. In this study we use an industry 3D seismic-reflection volume that encompasses the slope and shelfbreak surrounding the Gaviota submarine landslide (3.8 km2) to investigate structural …


Assessing The Utility Of Imaging Radar For Identifying White Sand Vegetation Structure, Jessica Rosenqvist Jan 2016

Assessing The Utility Of Imaging Radar For Identifying White Sand Vegetation Structure, Jessica Rosenqvist

Dissertations and Theses

White sand vegetation communities are wide spread across South America; found in Peru, Venezuela, Brazilian Amazon and Guyana. They are distributed in patches ranging from <1 km2 to greater than tens of square kilometers and their origins and locations are still not well understood. The communities are related to a variety of factors (soil type, flooding, nutrient content and fire); hence a precise definition for the ecosystem is still not fully defined. Nevertheless, the result of these variations creates a unique environment for endemic plant and animal species to thrive. Furthermore, analysis of these areas has been very scattered and identification of local white sand areas (<1 km2) have not been accomplished. In addition, identification of these locations has currently only used optical satellite imagery (Landsat, MODIS). Hence, in this project, we have attempted to use synthetic aperture radar to create a classification system to locate the white sand vegetation systems. The goal is to be able to apply this method to identify white sand vegetation distribution across South America. The region of focus for this thesis has been in Aracá, a large white sand area located in Brazil in the State of Amazonas. Due to the lack of ground reference data, a classified map by Capurucho et al. (2013), generated using Landsat data, was used as a comparison and reference. JAXA’s ALOS-1 PALSAR (L-band), ESA’s Sentinel-1A (C-band) and NASA’s SRTM sensors were used for land classification. As microwave signals penetrate clouds and haze, the advantage of using sensors with this wavelength allows for an unobstructed coverage of the landscape all year round. Different combinations of polarizations and wavelengths were used during the analysis to try and separate the white sand vegetation from water and terra firme forest. The resulting classification images showed a 30% agreement with the classification map by Capurucho et al. It is important to note, that this number is in fact an agreement percentage as the map used was a classification image and coarse in resolution (due to the lack of reference data). Therefore, this value does not imply a bad classification. Future work will include time-series data, precise ground reference points and data from other sensors such as ALOS-2 PALSAR, to improve the classification accuracy.


Geologic Time, John J. Renton, Thomas Repine Jan 2016

Geologic Time, John J. Renton, Thomas Repine

Readings and Notes

It is not surprising that humans have wondered how long Earth has existed. At one extreme, there were the Brahmans of India who believe that Earth never had a beginning and will never have an end. Others were of the opinion that Earth was old, but perhaps not eternally old. In 450 BC, for example, a Greek historian named Herodotus (484 - 425 BC) expressed the opinion that Earth was very old, basing his estimate on the results of his studies of the Nile Delta. He observed that the delta was growing layer by layer as a result of the …


Earthquakes And Seismology, John J. Renton, Thomas Repine Jan 2016

Earthquakes And Seismology, John J. Renton, Thomas Repine

Readings and Notes

The great majority of earthquakes are caused by the movement of faults. Two terms are used to determine the location of an earthquake, focus and epicenter. The focus of an earthquake is the point along a fault where the rocks slipped and released the energy previously stored during the elastic phase of deformation. Because faults represent brittle deformation, the highest frequency of earthquakes occurs at Earth's surface and decreases with depth as rocks become less brittle and more plastic. The deepest earthquake foci occur at depths of about 640 km. ( 400 mi.) which is the deepest penetration of subducting …


Earthquakes, John J. Renton, Thomas Repine Jan 2016

Earthquakes, John J. Renton, Thomas Repine

Readings and Notes

For centuries, earth scientists have known where the major earthquakes occurred. They also knew they occurred in the same locales as the most violent volcanoes, a fact that led to centuries of arguments as to which was the cause of the other. Now we know that they are not cause and effect; they are both associated with the convergent plate margins. During the mid-1900s, another major zone of both volcanic and earthquake activity was discovered, namely the divergent margins, the most important site being the oceanic ridges. Since then, we have also come to understand the occurrence of volcanic activity …


The Triassic Period And The Beginning Of The Mesozoic Era, John J. Renton, Thomas Repine Jan 2016

The Triassic Period And The Beginning Of The Mesozoic Era, John J. Renton, Thomas Repine

Readings and Notes

The Triassic Period is the first period of the Mesozoic Era, a span of time from 245 million years ago to 66 million years ago. Although the Mesozoic era commonly known as the "Age of the Dinosaurs,', it should be pointed out that there were other important evolutionary developments taking place such as the appearance of the first mammal birds and flowering plans. The onset of the Mesozoic Era, the Triassic Period, was also a time of profound tectonic activity affecting the entire North American craton. In the east, the primary event was the breakup of Pangea and the formation …


Coal Genesis, John J. Renton, Thomas Repine Jan 2016

Coal Genesis, John J. Renton, Thomas Repine

Readings and Notes

Most textbooks classify coal as a sedimentary rock even though it does not fit the definition of a sedimentary rock. While a sedimentary rock is a "rock formed from the products of weathering and erosion", coal forms from the remains of land plants. In fact, coal doesn't even fit the definition of a rock. A rock is defined as "mixture of minerals" and minerals are defined as "natural occurring, solid, inorganic substances ..• " Coal is composed largely (􀀴90+%) of organic substances (macerals) which, by definition, are not minerals. If coal must be classified as a rock, because it forms …


The Bou Dahar Jurassic Carbonate-Hosted Pb–Zn–Ba Deposits (Oriental High Atlas, Morocco): Fluid-Inclusion And C–O–S–Pb Isotope Studies, Larbi Rddad, Salah Bouhlel Jan 2016

The Bou Dahar Jurassic Carbonate-Hosted Pb–Zn–Ba Deposits (Oriental High Atlas, Morocco): Fluid-Inclusion And C–O–S–Pb Isotope Studies, Larbi Rddad, Salah Bouhlel

Publications and Research

The Bou Dahar Pb–Zn–Ba (±Sr) is hosted in the Lower and Middle Liassic carbonate platform in the oriental High Atlas of Morocco. The paragenetic sequence includes quartz–pyrite–melnicovite–sphalerite–galena– calcite–barite ± fluorite– ± celestite. Fluid-inclusion studies were conducted on sphalerite (early mineralizing stage) and barite, and celestite (late mineralizing stage). These studies reveal two end-member fluids, a hot (~143 °C) and saline fluid (~23 wt.% NaCl eq.) and a cooler (b50 °C) and diluted fluid (~5 wt.% NaCl eq.). Based on fluid-inclusion and C–O–S isotope studies, a conclusion is reached that the Bou Dahar ore deposits were formed by the mixing of …


Geochemistry Of Upper Cretaceous Sediments Of Bozeş Formation (Apuseni Mts., Romania) – Provenance Implications, Luminiţa Zaharia, Romona Bălc, Cosmin C. Stremţan, Adriana Socaciu Jan 2016

Geochemistry Of Upper Cretaceous Sediments Of Bozeş Formation (Apuseni Mts., Romania) – Provenance Implications, Luminiţa Zaharia, Romona Bălc, Cosmin C. Stremţan, Adriana Socaciu

School of Geosciences Faculty and Staff Publications

A whole-rock geochemical study was carried out on sandstones from the Upper Cretaceous Bozeş Formation in the southeastern part of the Apuseni Mountains (Romania) in order to constrain their provenance and depositional setting. The geochemical results were compared and integrated with previously reported provenance indicators, such as framework composition and heavy mineral assemblages. The chemical composition is similar for all samples investigated, with limited ranges for both major oxides and trace elements. The sandstones are potassic (Na2O/K2O < 1) and can be classified mainly as arenites with a few greywackes. Their immature to relatively mature character is revealed by the SiO2/Al2O3 ratios, ranging between 3.90 and 11.25, as well as their high Sr/Rb ratios. The …


Geographically Isolated Wetlands Are Part Of The Hydrological Landscape, Mark Rains, S. G. Leibowitz, M. J. Cohen, I. F. Creed, H. E. Golden, J. W. Jawitz, P. Kalla, C. R. Lane, M. W. Lang, D. L. Mclaughlin Jan 2016

Geographically Isolated Wetlands Are Part Of The Hydrological Landscape, Mark Rains, S. G. Leibowitz, M. J. Cohen, I. F. Creed, H. E. Golden, J. W. Jawitz, P. Kalla, C. R. Lane, M. W. Lang, D. L. Mclaughlin

School of Geosciences Faculty and Staff Publications

No abstract provided.


Paleosol Development And Trace Fossils In The Upper Triassic Cooper Canyon Formation Of The Dockum Group In Andrews County, Texas, Michael Charles Gratzer Jan 2016

Paleosol Development And Trace Fossils In The Upper Triassic Cooper Canyon Formation Of The Dockum Group In Andrews County, Texas, Michael Charles Gratzer

Honors Theses

It is unknown whether a relationship exists between paleosol development and the number of burrows in a paleosol. It is also unknown whether a relationship exists between the number of burrows in a paleosol and the diameters of those burrows. This paper details the methods, results, and conclusions of an investigation of these relationships. I assess the development of several paleosols in a core sample of the Upper Triassic Cooper Canyon Formation of the Dockum Group from well B-133 in Andrews County, Texas, using development scales based on methods from Bown and Kraus (1993) and Abels et al. (2013). I …


Statistical Analysis Of Arsenic Concentrations In Subsurface Soils At The University Of Mississippi Field Station, David Thomas Webb Jan 2016

Statistical Analysis Of Arsenic Concentrations In Subsurface Soils At The University Of Mississippi Field Station, David Thomas Webb

Honors Theses

The purpose of this investigation is to determine how arsenic concentration varies in soils with respect to soil structures, grain size, soil type, and depth. The investigation was conducted at the University of Mississippi Field Station (UMFS). The UMFS is located in Abbeville, MS and is roughly 700 acres in size. It includes ponds and former agricultural fields, and lies within an internally draining basin. Seven boreholes were drilled using a direct push geoprobe and sampled. The cores obtained from the borings were then cut at one foot intervals, producing a total of 90 soil samples. Each sample was observed …


Alongshore Momentum Balance Over Shoreface-Connected Ridges, Fire Island, Ny, Conor Ofsthun Jan 2016

Alongshore Momentum Balance Over Shoreface-Connected Ridges, Fire Island, Ny, Conor Ofsthun

Theses and Dissertations

Bathymetric variations, such as shoreface-connected ridges (SFCRs), modify inner shelf circulation, altering the significance of and relationships between alongshore momentum balance terms. The inner shelf of Fire Island, NY provides a study site representative of SFCRs around the world. During the winter of 2014, hydrodynamic observations (~12 m depth) from 6 ADCPs, 3 SeaGauge pressure sensors, 2 tide gauges, and 2 meteorological buoys were collected over a region of the inner shelf spanning a full wavelength of one such SFCR. Analysis of the data, under westward wind forcing, revealed a predominantly alongshore circulation with localized offshore (onshore) current veering over …


3d Seismic Depth Imaging And Velocity Model Building In Anisotropic Media: Serri Oil And Gas Field, Saudi Arabia, Ali Jomaah Alsalem Jan 2016

3d Seismic Depth Imaging And Velocity Model Building In Anisotropic Media: Serri Oil And Gas Field, Saudi Arabia, Ali Jomaah Alsalem

Theses and Dissertations

Seismic imaging is a significant element in hydrocarbon exploration to locate drilling prospects and it relies mainly on an accurate velocity model. Prestack depth migration (PreSDM) versus traditional post-stack time migration has become a common method for seismic velocity model building and imaging. This methodology accounts for seismic velocity anisotropy of the propagating waves in the subsurface with a higher level of accuracy in positioning the seismic events in their true positions in the subsurface.

In this thesis, we examine a 303 km2 of 3D seismic data acquired by Saudi Aramco in the Serri field of North-West Saudi Arabia. The …


New Hampshire Beaches: Sediment Characterization, Larry G. Ward, Kaitlyn A. Mcpherran, Zachary S. Mcavoy, Maxlimer Coromoto Vallee-Anziani Jan 2016

New Hampshire Beaches: Sediment Characterization, Larry G. Ward, Kaitlyn A. Mcpherran, Zachary S. Mcavoy, Maxlimer Coromoto Vallee-Anziani

Center for Coastal and Ocean Mapping

The grain size of the natural sediment composing the major New Hampshire beaches under summer equilibrium conditions was determined as a first step in assessing the optimal sediment size that would be needed for beach nourishment. In summer, 2015, seven major beaches including Wallis Sands, Foss Beach, Jenness Beach, North Hampton Beach, North Beach, Hampton Beach, and Seabrook Beach were sampled along three to five transects extending from the dunes or engineering structures (e.g., seawalls) to the low water line. In addition, the beach cross-section was profiled using a rover GPS system or the Emery method (profile rods and the …