Earth Sciences Commons^™

Mantle Dynamics Beneath The Discrete And Diffuse Plate Boundaries Of The Juan De Fuca Plate: Results From Cascadia Initiative Body Wave Tomography, Joseph S. Byrnes, Douglas R. Toomey, Emilie E. E. Hooft, John Nábělek, Jochen Braunmiller

School of Geosciences Faculty and Staff Publications

We use the delay times of teleseismic S phases recorded by ocean bottom seismometers during the plate‐scale Cascadia Initiative community experiment to constrain the heterogeneity of seismic velocity structure beneath young oceanic lithosphere. Our study area covers the entire Juan de Fuca (JdF) and Gorda plates, from their creation at the JdF and Gorda Ridges to their subduction beneath the North American continent, and the entire length of the Blanco transform fault. The range of the observed Vs anomalies requires variations in the melt fraction of the asthenosphere. The data require that low Vsanomalies extend to depths of at …

Slow Slip Events In The Early Part Of The Earthquake Cycle, Nicholas K. Voss, Rocco Malservisi, Timothy H. Dixon, Marino Protti

School of Geosciences Faculty and Staff Publications

In February 2014 a Mw = 7.0 slow slip event (SSE) took place beneath the Nicoya Peninsula, Costa Rica. This event occurred 17 months after the 5 September 2012, Mw = 7.6, earthquake and along the same subduction zone segment, during a period when significant postseismic deformation was ongoing. A second SSE occurred in the middle of 2015, 21 months after the 2014 SSE and 38 months after the earthquake. The recurrence interval for Nicoya SSEs was unchanged by the earthquake. However, the spatial distribution of slip for the 2014 event differed significantly from previous events, having only …

Sedimentary Characteristics And Nutrient Sequestration Of Embanked Floodplains Along The Lower Mississippi River, Mississippi And Louisiana, R M Malitha Rathnayake

Master's Theses

The Mississippi River Basin is the largest river basin in North America and the third largest river basin in the world. Most of the corn, soybeans, wheat, cattle, and hogs harvested in the United States come from the Mississippi River Basin and about 58% of the entire drainage basin is croplands. Runoff from these lands carries sediments and nutrients, and the Mississippi River transports these downstream and ultimately deposits them in the Gulf of Mexico. The northern Gulf of Mexico is one of largest human-caused hypoxic zones in the world. Hypoxia is the phenomena where the dissolved oxygen level decreases …

Quantifying Riverbed Sediment Using Recreational-Grade Side Scan Sonar, Daniel Hamill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Colorado River in Glen, Marble, and Grand Canyons is subject to a complex regulatory framework, including the Colorado River Compact, the Endangered Species Act, and the Grand Canyon Protection Act of 1992. Physical, biological, and cultural resources are extensively monitored by the Glen Canyon Dam Adaptive Management Program (GCDAMP) to assess the effect of Glen Canyon Dam (GCD) operations on the downstream environment. The GCDAMP consists of a diverse group of stakeholders who identify priority resources and agree upon water releases at GCD. Large expenditures of money have been devoted to monitoring physical and biological resources in Grand Canyon. …

Characterizing The Low Net-To-Gross, Fluviodeltaic Dry Hollow Member Of The Frontier Formation, Western Green River Basin, Wyoming, Scott Romney Meek

Theses and Dissertations

The Frontier Formation in the Green River Basin of southwestern Wyoming consists of Late Cretaceous (Cenomanian-Turonian) marine and non-marine sandstones, siltstones, mudstones and coals deposited on the western margin of the Cretaceous Interior Seaway. Tight gas reservoirs exist in subsurface fluviodeltaic sandstones in the upper Frontier Formation (Dry Hollow Member) on the north-south trending Moxa Arch within the basin. These strata crop out in hogback ridges of the Utah-Idaho-Wyoming Thrust Belt approximately 40 km west of the crest of the Moxa Arch. Detailed, quantitative outcrop descriptions were constructed using emerging photogrammetric techniques along with field observations and measured sections at …

Geologic Mapping Of The Vernal Nw Quadrangle, Uintah County, Ut, And Stratigraphic Relationships Of The Duchesne River Formation And Bishop Conglomerate, Casey Andrew Webb

Theses and Dissertations

Detailed mapping (1:24,000), measured sections, and clast counts in conglomerates of the Duchesne River Formation and Bishop Conglomerate in the Vernal NW quadrangle in northeastern Utah reveal the middle Cenozoic stratigraphic geometry, the uplift and unroofing history of the eastern Uinta Mountains, and give evidence for the pulsed termination of Laramide uplift. The Unita Mountains are an EW-trending reverse fault bounded and basement-cored, Laramide uplift. The oldest unit of the Duchesne River Formation, the Eocene Brennan Basin Member, contains 80-90% Paleozoic clasts and <20% Precambrian clasts. Proximal to the Uinta uplift the conglomerates of this member are dominated by Paleozoic Madison Limestone clasts (70-90% of all clasts). Farther out into the basin, Paleozoic clasts still dominate in Brennan Basin Member conglomerates, but chert clasts are more abundant (up to 43%) showing the efficiency of erosion of the carbonate clasts over a short distance (~5 km). Conglomerates in the progressively younger Dry Gulch Creek, Lapoint, and Starr Flat members show a significant upward increase in Precambrian clasts with 34-73% Uinta Mountain Group and 8-63% Madison Limestone. Duchesne River Formation has a significant increase in coarse-grained deposits from the southern parts of the quadrangle (20-50% coarse) to the northern parts (75% coarse) nearer the Uinta uplift. The lower part of the Duchesne River Formation exhibits a fining upward sequence representing a tectonic lull. Clast count patterns show that pebbly channel deposits in the south maintain similar compositions to their alluvial fan counterparts. To the north, the fine-grained Lapoint and Dry Gulch Creek members of the Duchesne River Formation appear to pinch out completely. This can be explained by erosion of these fine-grained deposits or by lateral facies shifts before deposition of the next unit. Starr Flat Member conglomerates were deposited above Lapoint Member siltstones and represent southward progradation of alluvial fans away from the uplifting mountain front. Similarities in composition and sedimentary structures have caused confusion surrounding the contact between the Starr Flat Member and the overlying Bishop Conglomerate. Within the Vernal NW quadrangle, we interpret this contact as an angular unconformity (the Gilbert Peak Erosion Surface) developed on the uppermost tilted red siltstone of the Starr Flat Member sometime after 37.9 Ma. Stratigraphic and structural relationships reveal important details about the development of a Laramide mountain range: 1) sequential unroofing sequences in the Duchesne River Formation, 2) progradation of alluvial fans to form the Starr Flat Member, 3) and the unconformable nature of the Gilbert Peak Erosion Surface lead to the conclusion that there were at least 3 distinct episodes of uplift during the deposition of these formations. The last uplift episode upwarped the Starr Flat Member constraining the termination of Laramide uplift in the Uinta Mountains to be after deposition of the Starr Flat Member and prior to deposition of the horizontal Bishop Conglomerate starting at about 34 Ma. This, combined with ⁴⁰Ar/³⁹Ar ages of 39.4 Ma from the Dry Gulch Creek and Lapoint member, show …

Upscaling Capillary Pressure–Saturation Functions Using Different Reference Pressure Elevations, Chu-Lin Cheng, S. Clark Cropper, Edmund Perfect, Larry Mckay, Misun Kang

School of Earth, Environmental, & Marine Sciences Faculty Publications

Choice of reference pressure elevation (RPE) on average effective saturation–capillary pressure functions, 〈〉(ψ), was investigated for monotonic drainage of homogeneous porous media. Nine columns of Flint sand with heights ranging from 4.3 to 55.0 cm were prepared. Measured 〈〉(ψ) functions were determined gravimetrically using the hanging water column method. Predicted 〈〉(ψ) functions were obtained by upscaling point function parameters determined by neutron radiographic imaging of a single drainage experiment. Bottom and midpoint RPEs resulted in the inaccurate parameterization of 〈〉(ψ) functions for tall columns. A top RPE produced accurate upscaled functions for all column heights. To evaluate the overall performance …

Impact Of Salinity Change On Water Quality Variables From The Sediment Of An Artificial Lake Under Anaerobic Conditions, Tae-Hoon Kim, James Jihoon Kang, Sang Hyun Kim, I-Song Choi, Kwang-Hyeon Chang, Jong Min Oh, Ki-Hyun Kim

School of Earth, Environmental, & Marine Sciences Faculty Publications

Artificial reservoirs are created by dike construction in coastal areas to secure the agricultural water supply on the west coast of South Korea. These systems are found to retain brackish characteristics until total desalination is achieved. To evaluate the effects of salinity on the organic substances released from the sediment, a laboratory water-sediment column experiment was conducted to assess associated changes in water quality variables such as the sediment oxygen demand (SOD), chemical oxygen demand (COD), and concentrations of nitrogen (N) and phosphorus (P). Under high salinity conditions, the release of N from the sediment was promoted with the enhancement …

Stratigraphy Of The Middle Cambrian Lincoln Peak Formation And Evolution Of The House Range Embayment, Eastern Nevada, Ibrahim Zallum

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

This study examined the Middle Cambrian (c. 500 MA) Lincoln Peak Formation and Patterson Pass Shale. The initial goal was to create a stratigraphic model for these units. This model was then compared to those from already studied units in western Utah, which combined with the Nevada units form the rock record of an ancient feature known as the House Range Embayment, which was an area of greater water depth superimposed on the continental shelf. This study found that the Nevada units exhibit a series of depositional sequences similar to those in western Utah, but at a lower resolution. This …

The Dynamic Relationship Between The Bear River, Quaternary Basaltic Center, Normal Faults, And The Resulting Rearrangement Of Rivers In The Northeast Edge Of The Great Basin, Southeast Idaho, Brady Utley

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

The objective of this research project in Gem Valley graben, southeast Idaho is to identify the location, age and history of the Quaternary diversion of the Bear River into paleo-Lake Thatcher, and then into the Lake Bonneville basin from the Columbia River basin. Mapping, geochemical analysis, cross-cutting relationships, and five new age determinations, together with prior published research, shed new light on the complex history of interaction between the volcanic rocks, rivers, lakes, and faults in Gem Valley. Research goals were to test the hypothesis that local faulting and volcanism drove the diversion of the Bear River and controlled the …

Vulnerability Assessment Of Groundwater To No3 Contamination Using Gis, Drastic Model And Geostatistical Analysis, Adela Beauty Adu Agyemang

Electronic Theses and Dissertations

The study employed Geographical Information System (GIS) technology to investigate the vulnerability of groundwater to NO₃ content in Buncombe County, North Carolina in two different approaches. In the first study, the spatial distribution of NO₃ contamination was analyzed in a GIS environment using Kriging Interpolation. Cokriging interpolation was used to establish how NO₃ relates to land cover types and depth to water table of wells in the county. The second study used DRASTIC model to assess the vulnerability of groundwater in Buncombe County to NO₃ contamination. To get an accurate vulnerability index, the DRASTIC parameters were …

Using Stable Isotope Geochemistry To Determine Changing Paleohydrology And Diagenetic Alteration In The Late Cretaceous Kaiparowits Formation, Ut Usa, Daigo Yamamura

Graduate Theses and Dissertations

The Western Interior Basin of the North America preserves one of the best sedimentary and paleontological records of the Cretaceous in the world. The Upper Cretaceous Kaiparowits Formation is a rapidly deposited fluvial sequence and preserves one of the most complete terrestrial fossil record of the North America. Such a unique deposit provides an opportunity to investigate the interaction between the physical environment and ecology. In an effort to decipher such interaction, stable isotope composition of cements in sedimentary rocks, concretions and vertebrate fossils were analyzed.

Despite the difference in facies and sedimentary architecture, the isotope composition does not change …

Near Surface Geophysics For Lithostratigraphic Interpretation At Pedro, Benton County, Arkansas, Matthew David Ruggeri

Graduate Theses and Dissertations

The roadcut on highway 412 near Pedro, Benton County, Arkansas (MArkUP site L15), has been of geological interest since its excavation in the 1980s. The roadcut is located within the Springfield Plateau and displays formations of Lower Mississippian age. The roadcut contains three mound-like features believed to be olistoliths. This thesis research work adds geophysical evidence to the geological exposure at the site. The purpose of this research is to answer the question of whether near surface seismic methods can be used to extend information at the Pedro outcrop below the ground surface. Specifically, can the top of the Middle …

Characterization Of The Relationships Between Soybean Yield, Trifoliolate Leaf Chloride Concentration, And Cultivar Chloride Inclusion/Exclusion Rating, Dillon Cox

Graduate Theses and Dissertations

Chloride toxicity is recognized as yield limiting problem in soybean [Glycine max (L.) Merr.] production. Limited information is available to accurately diagnose and manage Cl toxicity. The only recommendation for Cl toxicity management is to plant an excluder cultivar, however the cultivar Cl sensitivity rating system (excluder, includer, and mixed) does not appear to capture the variability in cultivar Cl tolerance. The objectives of this research were to i) develop critical tissue-Cl concentrations in which yield loss occurs for excluder and includer cultivars and ii) investigate the variability in cultivar Cl ratings. A study was conducted across five site-years using …

A Geologic Study To Determine The Potential To Create An Appalachian Storage Hub For Natural Gas Liquids, Kristin M. Carter, Douglas G. Patchen, Jessica P. Moore, Mohammad Fakhari, Gary W. Daft Jr, Michael Solis, Brian J. Dunst, Robin V. Anthony, Katherine W. Schmid, Kyle Metz, Philip Dinterman, Julie M. Bloxson, Erica N. Schubert, John Saucer

Appalachian Oil and Natural Gas Research Consortium

The Marcellus and Utica shale plays continue to lead the way in an ever-expanding shale revolution with average daily production, growing from about 3 billion cubic feet (BCF) in 2010 to more than 24 BCF today. Forecasts suggest that this could grow to as much as 40 BCF in the next 5 years. Fortunately, sweet spots in the Utica in eastern Ohio and in the Marcellus in northern West Virginia and southwestern Pennsylvania are areas of wet gas production, downdip from oil production and updip from dry gas. Production in these regions represents about 40 percent of the total from …

New Biotite And Muscovite Isotopic Reference Materials, Usgs57 And Usgs58, For Δ2h Measurements–A Replacement For Nbs 30, Haiping Qi, Tyler B. Coplen, Matthias Gehre, Torsten W. Vennemann, Willi A. Brand, Heike Geilmann, Gerald Olack, Ilya N. Bindeman, Jim Palandri, Li Huang, Fred J. Longstaffe

Earth Sciences Publications

The advent of continuous-flow isotope-ratio mass spectrometry (CF-IRMS) coupled with a high temperature conversion (HTC) system enabled faster, more cost effective, and more precise δ²H analysis of hydrogen-bearing solids. Accurate hydrogen isotopic analysis by on-line or off-line techniques requires appropriate isotopic reference materials (RMs). A strategy of two-point calibrations spanning δ²H range of the unknowns using two RMs is recommended. Unfortunately, the supply of the previously widely used isotopic RM, NBS 30 biotite, is exhausted. In addition, recent measurements have shown that the determination of δ²H values of NBS 30 biotite on the VSMOW-SLAP …

Geochemistry Of Volatiles Released By Incipient Continental Rifting And Subduction Processes, Hyunwoo Lee

Earth and Planetary Sciences ETDs

Volatiles (N2, CO2, and He) are released by volcanism and hydrothermal activity during continental rifting and subduction processes. Analyses of volatile components have been conducted to obtain gas contents (CO2, SO2, H2S, N2, Ar, He, and so on), stable isotope compositions (δ13C, δ15N, and so on), and noble gas isotopes (3He/4He, 40Ar/36Ar, and so on). This dissertation includes four chapters to report new nitrogen isotope fractionation factors of bubbling gases during gas-water transfer at various water temperatures (Chapter 1), first measurements of massive amounts of CO2 released by incipient continental rifting in the Magadi and Natron Basin, East African Rift …

Microfeatures Of Modern Sea-Ice-Rafted Sediment And Implications For Paleo-Sea-Ice Reconstructions, Kristen E. St. John, Sandra Passchier, Brooke Tantillo, Dennis Darby, Lance Kearns

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Distinguishing sea-ice-rafted debris (SIRD) from iceberg-rafted debris is crucial to an interpretation of ice-rafting history; however, there are few paleo-sea-ice proxies. This study characterizes quartz grain microfeatures of modern SIRD from the Arctic Ocean, and compares these results with microfeatures from representative glacial deposits to potentially differentiate SIRD from ice-rafted sediments which have been recently subjected to glacial processes. This allows us to evaluate the use of grain microfeatures as a paleo-sea-ice proxy. SIRD grains were largely subrounded, with medium relief, pervasive silica dissolution and a high abundance of breakage blocks and microlayering. The glacial grains were more angular, with …

Origin Of Primitive Ocean Island Basalts By Crustal Gabbro Assimilation And Multiple Recharge Of Plume-Derived Melts, Anastassia Y. Borisova, Wendy A. Bohrson, Michel Grégoire

All Faculty Scholarship for the College of the Sciences

Chemical Geodynamics relies on a paradigm that the isotopic composition of ocean island basalt (OIB) represents equilibrium with its primary mantle sources. However, the discovery of huge isotopic heterogeneity within olivine‐hosted melt inclusions in primitive basalts from Kerguelen, Iceland, Hawaii and South Pacific Polynesia islands implies open‐system behavior of OIBs, where during magma residence and transport, basaltic melts are contaminated by surrounding lithosphere. To constrain the processes of crustal assimilation by OIBs, we employed the Magma Chamber Simulator (MCS), an energy‐constrained thermodynamic model of recharge, assimilation and fractional crystallization. For a case study of the 21–19 Ma basaltic series, the …

Effects Of Climate Warming On Net Primary Productivity In China During 1961–2010, Fengxue Gu, Yuandong Zhang, Mei Huang, Bo Tao, Rui Guo, Changrong Yan

Plant and Soil Sciences Faculty Publications

The response of ecosystems to different magnitudes of climate warming and corresponding precipitation changes during the last few decades may provide an important reference for predicting the magnitude and trajectory of net primary productivity (NPP) in the future. In this study, a process-based ecosystem model, Carbon Exchange between Vegetation, Soil and Atmosphere (CEVSA), was used to investigate the response of NPP to warming at both national and subregional scales during 1961–2010. The results suggest that a 1.3°C increase in temperature stimulated the positive changing trend in NPP at national scale during the past 50 years. Regardless of the magnitude of …

Coupling Biophysical Processes And Water Rights To Simulate Spatially Distributed Water Use In An Intensively Managed Hydrologic System, Bangshuai Han, Shawn G. Benner, John P. Bolte, Kellie B. Vache, Alejandro N. Flores

Geosciences Faculty Publications and Presentations

Humans have significantly altered the redistribution of water in intensively managed hydrologic systems, shifting the spatiotemporal patterns of surface water. Evaluating water availability requires integration of hydrologic processes and associated human influences. In this study, we summarize the development and evaluation of an extensible hydrologic model that explicitly integrates water rights to spatially distribute irrigation waters in a semi-arid agricultural region in the western US, using the Envision integrated modeling platform. The model captures both human and biophysical systems, particularly the diversion of water from the Boise River, which is the main water source that supports irrigated agriculture in this …

Assessing Coastal Plain Risk Indices For Subsurface Phosphorus Loss, Amy L. Shober, Anthony R. Buda, Kathryn C. Turner, Nicole M. Fiorellino, A. Scott Andres, Joshua M. Mcgrath, J. Thomas Sims

Plant and Soil Sciences Faculty Publications

Phosphorus (P) Index evaluations are critical to advancing nutrient management planning in the United States. However, most assessments until now have focused on the risks of P losses in surface runoff. In artificially drained agroecosystems of the Atlantic Coastal Plain, subsurface flow is the predominant mode of P transport, but its representation in most P Indices is often inadequate. We explored methods to evaluate the subsurface P risk routines of five P Indices from Delaware, Maryland (two), Virginia, and North Carolina using available water quality and soils datasets. Relationships between subsurface P risk scores and published dissolved P loads in …

Highly Variable Recurrence Of Tsunamis In The 7,400 Years Before The 2004 Indian Ocean Tsunami, Charles M. Rubin, Benjamin P. Horton, Kerry Sieh, Jessica E. Pilarczyk, Patrick Daly, Nazli Ismail, Andrew C. Parnell

Faculty Publications

The devastating 2004 Indian Ocean tsunami caught millions of coastal residents and the scientific community off-guard. Subsequent research in the Indian Ocean basin has identified prehistoric tsunamis, but the timing and recurrence intervals of such events are uncertain. Here we present an extraordinary 7,400 year stratigraphic sequence of prehistoric tsunami deposits from a coastal cave in Aceh, Indonesia. This record demonstrates that at least 11 prehistoric tsunamis struck the Aceh coast between 7,400 and 2,900 years ago. The average time period between tsunamis is about 450 years with intervals ranging from a long, dormant period of over 2,000 years, to …

Brackish Groundwater And Its Potential To Augment Freshwater Supplies, Jennifer S. Stanton, Kevin F. Dennehy, Sharon L. Qi, Alta C. Harris

United States Geological Survey: Water Reports and Publications

Document abstract

Secure, reliable, and sustainable water resources are fundamental to the Nation’s food production, energy independence, and ecological and human health and well-being. Indications are that at any given time, water resources are under stress in selected parts of the country. The large-scale development of groundwater resources has caused declines in the amount of groundwater in storage and declines in discharges to surface water bodies (Reilly and others, 2008). Water supply in some regions, particularly in arid and semiarid regions, is not adequate to meet demand, and severe drought intensifies the stresses affecting water resources (National Drought Mitigation Center, …

Herald Journal Article About Iutah Team Symposium, Utah Water Research Laboratory

News

A team of researchers from USU and other Utah universities, government agencies, industry partners, and non-rofit organizations came together 5 years ago to establish iUTAH (Innovative Urban Transition and Aridregion Hydro-sustainability) as a way to strengthen science for Utah's water future. This 5-year interdisciplinary research and training program was funded by the National Science Foundation through July 2017. These researchers, including UWRL faculty members Jeff Horsburgh, Bethany Neilson, and David Rosenberg recently presented a symposium to present their progress and accomplishments over the course of this enormous undertaking.

Moving From Generalisations To Specificity About Mangrove –Saltmarsh Dynamics, Kerrylee Rogers, Ken W. Krauss

United States Geological Survey: Staff Publications

Spatial and temporal variability in factors influencing mangrove establishment and survival affects the distribution of mangrove, particularly near their latitudinal limit, where mangrove expansion into saltmarsh is conspicuous. In this paper the spatial variability in mangrove distribution and variability in factors influencing mangrove establishment and survival during the Quaternary period are reviewed, focusing on research at latitudinal limits in Australia and mainland USA. Despite similarities in the response of mangrove to some drivers, the expression of these drivers is both spatially and temporally variable, demonstrating the need for analyses of mangrove-saltmarsh dynamics to move beyond generalizations and incorporate regional and …

Trilobite Extinctions, Facies Changes And The Roece Carbon Isotope Excursion At The Cambrian Series 2–3 Boundary, Great Basin, Western Usa, Luke E. Faggetter, Paul B. Wignall, Sara B. Pruss, Robert J. Newton, Yadong Sun, Stephen F. Crowley

Geosciences: Faculty Publications

The mass extinction of the olenellid trilobites occurred around the Cambrian Series 2–Series 3 boundary. Like many other crises, it coincided with a negative carbon isotope excursion but the associated palaeoenvironmental changes remain unclear. To investigate the causal mechanism for this event, we report facies changes, pyrite framboid petrography and carbon isotope values from Cambrian Series 2–Series 3 (traditionally Early–Middle Cambrian) boundary strata of the Carrara Formation (Death Valley region, California) and Pioche Formation (Nevada). These data reveal regionally changing water depths from high-energy, nearshore facies (oolitic grainstone) to more offshore silty marl and finer-grained carbonate mudstone. In the Carrara …

Aggieair Begin The 2017 Flight Season, Aggieair

News

The AggieAir team kicks off a busy 2017 in Sunny California by placing strategically placed targets across the Gallo Family vineyards. These targets are crucial to georectify UAV imagery.

The Littlefield Rhyolite, Eastern Oregon: Distinct Flow Units And Their Constraints On Age And Storage Sites Of Grande Ronde Basalt Magmas, Brian Mcculloch Webb

Dissertations and Theses

The Littlefield Rhyolite consists of widespread, high-temperature, hotspot-related rhyolitic lavas that erupted in eastern Oregon contemporaneous to late-stage Grande Ronde Basalt lavas. The estimated total volume of erupted rhyolites is ~100 km³ covering ~850 km².

The focus of this study has been to investigate the stratigraphy and petrology of the Littlefield Rhyolite and whether field and geochemical relationships exist to help constrain the timing and storage sites of Grande Ronde Basalt magmas. Although often indistinguishable in the field, our data reveal that the Littlefield Rhyolite consists of two geochemically distinct rhyolite flow packages that are designated here …

Examining The Use Of Amazon’S Mechanical Turk For Edge Extraction Of The Occlusal Surface Of Fossilized Bovid Teeth, George K. Thiruvathukal, Gregory J. Matthews, Maxwell P. Luetkemeier, Juliet K. Brophy

Computer Science: Faculty Publications and Other Works

In order to reconstruct environments associated with Plio-Pleistocene hominins in southern Africa, researchers frequently rely upon the animals associated with the hominins, in particular, animals in the Family Bovidae. Bovids in southern Africa are typically identified by their teeth. However, identifying the taxon of a bovid tooth is challenging due to various biasing factors. Furthermore, inaccurate identification of fossil bovids can have significant consequences on the reconstructed paleoenvironment. Recent research on the classification of bovid fossil teeth has relied on using elliptical Fourier analysis to summarize the shape of the outline of the occlusal surface of the tooth and the …