Earth Sciences Commons^™

Diversity, Trends, Opportunities And Challenges In Australian Grasslands–Meeting The Sustainability And Productivity Imperatives Of The Future?, Lindsay W. Bell, Richard C. Hayes, Keith G. Pembleton, Cathy M. Waters

IGC Proceedings (1977-2023)

Grassland production systems contribute 40% to Australia’s gross agricultural production value and utilise over 50% of its land area. Across this area a broad diversity of systems exist, but these can be broadly classified into four main production systems: 1. Pastoral grazing of mainly cattle at low intensity (i.e. < 0.4 DSE/ha) on relatively unimproved native rangelands in the arid and semi-arid regions of northern and central Australia; 2. Crop-livestock systems in the semi-arid zone where livestock graze a mixture of pastures and crops which are often integrated; 3. High rainfall permanent pasture zone in the coastal hinterland and highlands and; 4. Dairy systems covering a broad range of environments and production intensities. A notable trend across these systems has been the replacement of wool sheep with beef cattle or meat sheep breeds, which has been driven by low wool prices. Although there is evidence that most of these systems have lifted production efficiencies over the past 30 years, total factor productivity growth has failed to match the decline in terms of trade. This has renewed attention on how research and development can help increase productivity. In addition, these industries are facing increasing scrutiny to improve their environmental performance and develop sustainable production practices. We propose several areas in which grasslands research and development might help provide gains in system productivity and sustainability. In particular, pasture productivity might be improved by filling gaps in the array of pastures available either through exploring new species or improving the adaptation and agronomic characteristics of species currently sown. Meanwhile there is a need to maintain efforts to overcome persistent and emerging constraints to pasture productivity. Improving livestock forage feed systems and more precise and lower cost management of grasslands would translate into improved utilisation and conversion of forage produced into livestock products. There is significant scope to capture value from the ecological services grasslands provide and mitigate greenhouse gas emissions from livestock production. Multi-purpose grasslands provide not only grazing for livestock but produce other food products such as grain which may also have potential to integrate livestock with cropping. However, reduced human research capacity in pasture science will challenge our ability to realise these potential opportunities unless efforts are made to attract and support a new generation of pasture scientists.

Managing Grassland Systems In A Changing Climate: The Search For Practical Solutions, Jean-François Soussana, Luis Gustavo Barioni, Tamara Ben Ari, Rich Conant, Pierre Gerber, Petr Havlik, Alexandre Ickowicz, Mark Howden

IGC Proceedings (1977-2023)

By the end of the XXI^st century, a global temperature rise between 1.5 and 4°C compared to 1980-1999 and CO₂ concentrations in the range 550-900 ppm are expected, together with an increased frequency of extreme climatic events (heat waves, droughts, and heavy rain) that is likely to negatively affect grassland production and livestock systems in a number of world regions. Grassland management has a large potential to mitigate livestock greenhouse gas emissions at a low (or even negative) cost, by combining a moderate intensification, the restoration of degraded pastures and the development of silvo-pastoral systems. Climate change vulnerability …

Feeding The World In 2050: Trade-Offs, Synergies And Tough Choices For The Livestock Sector, Jimmy Smith, Shirley Tarawali, Delia Grace, Keith Sones

IGC Proceedings (1977-2023)

Feeding the World in 2050 is a major challenge at the forefront of the global development agenda. The importance of agriculture in addressing this challenge has re-emerged in recent years as food security issues are considered in a more holistic manner. The role of livestock as part of the solution is, however, often not considered. This article presents a brief overview of the global food security challenge, and considers the increased focus on holistic food systems. It contends that animal agriculture is relevant to this complex, multifaceted and dynamic global challenge. However, if livestock-based solutions are to become a reality …

Front Matter [22nd International Grassland Congress Proceedings], Organizing Committee, International Grassland Congress

IGC Proceedings (1977-2023)

No abstract provided.

Evidence Of Variable Climate And Resources During The Late Pleistocene And Holocene At Gona, Ethiopia, Marie White

Steeplechase: An ORCA Student Journal

The African Humid Period (AHP) spanned a period of approximately 15 to 5 thousand years ago (ka) and resulted in Northern and Eastern Africa being wetter than today. This climate change event impacted flora, fauna, and humans to an unknown extent. Much of the work on the AHP across Eastern Africa utilizes lacustrine and marine proxies rather than river-based (fluvial). Gona, located in the Afar region of Ethiopia, is known for its extensive archaeological and fossil records in fluvial deposits. However, the paleoenvironment of the AHP at Gona has not been investigated. This study uses stratigraphy, geochronology, and paleopedology to …

Crustal Density Variation Of The Eastern U.S., Henglei Zhang, Dhananjay Ravat, Anthony R. Lowry

Earth and Environmental Sciences Research Data

EarthScope’s USArray Transportable Array (TA) has shortcomings for the purpose of interpreting geologic features of wavelengths less than the 70 km TA station spacing, but these can be overcome by using higher spatial resolution gravity data. In this study, we exploit USArray receiver functions to reduce non-uniqueness in the interpretation of gravity anomalies. We model gravity anomalies from previously-derived density variations of sedimentary basins, crustal Vp/Vs variation, Moho variation, and upper mantle density variation derived from body-wave imaging informed by surface wave tomography to estimate Vp/Vs. Although average densities and density contrasts for these seismic variations can be derived, …

Chemostratigraphic Correlations Across The First Major Trilobite Extinction And Faunal Turnovers Between Laurentia And South China, Jih-Pai Lin, Frederick A. Sunberg, Ganqing Jiang, Isabel P. Montanez, Thomas Wotte

Geoscience Faculty Research

During Cambrian Stage 4 (~514 Ma) the oceans were widely populated with endemic trilobites and three major faunas can be distinguished: olenellids, redlichiids, and paradoxidids. The lower–middle Cambrian boundary in Laurentia was based on the first major trilobite extinction event that is known as the Olenellid Biomere boundary. However, international correlation across this boundary (the Cambrian Series 2–Series 3 boundary) has been a challenge since the formal proposal of a four-series subdivision of the Cambrian System in 2005. Recently, the base of the international Cambrian Series 3 and of Stage 5 has been named as the base of the Miaolingian …

The Effect Of The 21 August 2017 Total Solar Eclipse On The Phase Of Vlf/Lf Signals, A. Rozhnoi, M. Solovieva, S. Shalimov, Dimitar Ouzounov, P. Gallagher, G. Verth, J. Mccauley, S. Shelyag, V. Fedun

Mathematics, Physics, and Computer Science Faculty Articles and Research

An experimental study of the phase and amplitude observations of sub‐ionospheric very low and low frequency (VLF/LF) signals is performed to analyze the response of the lower ionosphere during the 21 August 2017 total solar eclipse in the United States of America. Three different sub‐ionospheric wave paths are investigated. The length of the paths varies from 2,200 to 6,400 km, and the signal frequencies are 21.4, 25.2, and 40.75 kHz. The two paths cross the region of the total eclipse, and the third path is in the region of 40–60% of obscuration. None of the signals reveal any noticeable amplitude …

Sampling Methods For Luminescence Dating Of Subsurface Deposits From Cores, Michelle Nelson, Tammy M. Rittenour, Harriet Cornachione

Geosciences Faculty Publications

Study of subsurface deposits often requires coring or drilling to obtain samples for sedimentologic and geochemical analysis. Geochronology is a critical piece of information for stratigraphic correlation and rate calculations. Increasingly, luminescence dating is applied to sediment cores to obtain depositional ages. This paper provides examples and discussion of guidelines for sampling sediment core for luminescence dating. Preferred protocols are dependent on the extraction method, sedimentology, core integrity, and storage conditions. The methods discussed include subsampling of sediment in opaque core-liners, cores without liners, previously open (split) cores, bucket auger samples, and cuttings, under red lighting conditions. Two important factors …

Insights To The Genetic Structure Of Calanus Helgolandicus (Calanoida: Copepoda) From Deep-Sea Specimens In The Balearic Sea, Diego F. Figueroa, Joan E. Cartes, Nicole J. Figueroa

School of Earth, Environmental, & Marine Sciences Faculty Publications

Calanus helgolandicus is widely distributed across the northeast Atlantic and Mediterranean, and also found in the Black Sea where it is referred to as Calanus euxinus. Previous genetic studies do not include deep-water specimens despite high abundances at bathypelagic and mesopelagic depths. Our objective is to compare the genetic structure of C. heloglandicus from the deep Balearic Sea to that of coastal populations in the Northeastern Atlantic Ocean, the Adriatic Sea, and the Black Sea defined from previous research. We use a portion of the mitochondrial gene cytochrome oxidase I from 41 individuals of C. helgolandicus collected at 2170 m …

Mitogenomic Phylogenetic Analyses Of Leptogorgia Virgulata And Leptogorgia Hebes (Anthozoa: Octocorallia) From The Gulf Of Mexico Provides Insight On Gorgoniidae Divergence Between Pacific And Atlantic Lineages, Samantha Silvestri, Diego F. Figueroa, David Hicks, Nicole J. Figueroa

School of Earth, Environmental, & Marine Sciences Faculty Publications

The use of genetics in recent years has brought to light the need to reevaluate the classification of many gorgonian octocorals. This study focuses on two Leptogorgia species—Leptogorgia virgulata and Leptogorgia hebes—from the northwestern Gulf of Mexico (GOM). We target complete mitochondrial genomes and mtMutS sequences, and integrate this data with previous genetic research of gorgonian corals to resolve phylogenetic relationships and estimate divergence times. This study contributes the first complete mitochondrial genomes for L. ptogorgia virgulata and L. hebes. Our resulting phylogenies stress the need to redefine the taxonomy of the genus Leptogorgia in its entirety. The fossil-calibrated divergence …

Postmagmatic Tectonic Evolution Of The Outer Izu‐Bonin Forearc Revealed By Sediment Basin Structure And Vein Microstructure Analysis: Implications For A 15 Ma Hiatus Between Pacific Plate Subduction Initiation And Forearc Extension, Walter Kurz, Peter Micheuz, Gail L. Christeson, M. Reagan, John W. Shervais, Steffen Kutterolf, A. Robertson, Kurt Krenn, K. Michibayashi, D. Quandt

Geosciences Faculty Publications

International Ocean Discovery Program Expedition 352 recovered sedimentary‐volcaniclastic successions and extensional structures (faults and extensional veins) that allow the reconstruction of the Izu‐Bonin forearc tectonic evolution using a combination of shipboard core data, seismic reflection images, and calcite vein microstructure analysis. The oldest recorded biostratigraphic ages within fault‐bounded sedimentary basins (Late Eocene to Early Oligocene) imply a ~15 Ma hiatus between the formation of the igneous basement (52 to 50 Ma) and the onset of sedimentation. At the upslope sites (U1439 and U1442) extension led to the formation of asymmetric basins reflecting regional stretch of ~16–19% at strain rates of …

The Complete Mitochondrial Genome Of Tanacetipathes Thamnea Warner, 1981 (Antipatharia: Myriopathidae), Diego F. Figueroa, David Hicks, Nicole J. Figueroa

School of Earth, Environmental, & Marine Sciences Faculty Publications

Specimens of the black coral Tanacetipathes thamnea were collected from the Northwestern Gulf of Mexico. The complete mitochondrial genome of one of these specimens was obtained from genomic DNA by next-generation sequencing technology on the Illumina HiSeq 2500. Only three species of black corals have a completely sequenced mitochondrial genome. These were used to reconstruct the phylogeny for the order Antipatharia. The mitochondrial genome of T. thamnea is 17,712 base pairs and contains 13 protein-coding genes, 2 ribosomal RNAs, and 2 transfer RNAs in the following order: 16s RNA, COX3, COX1 (with intron), ND4L, COX2, ND4, …

Reconstructing Geographic And Trophic Histories Of Fish Using Bulk And Compound-Specific Stable Isotopes From Eye Lenses, Amy A. Wallace

USF Tampa Graduate Theses and Dissertations

The present research examined the viability and utility of eye lenses as a source of lifetime stable-isotope records in fish. It is presented in three sections. The first section compared bulk isotopic variation (bulk analysis) within fish eye-lenses at two temporal resolutions and compared patterns obtained from left and right eyes. The first temporal resolution was lower in an attempt to expose broad-scale isotopic changes during life while reducing effort and cost. This approach did reveal lifetime patterns, but tended to miss certain life events, particularly during early life. The second resolution was higher and provided detail that was missed …

Non-Invasive Methods For Measuring And Monitoring Stress Physiology In Imperiled Amphibians, Edward J. Narayan, Zachery R. Forsburg, Drew R. Davis, Caitlin R. Gabor

School of Earth, Environmental, & Marine Sciences Faculty Publications

Global climate change is negatively impacting global biodiversity and ectothermic vertebrates, with amphibians being the most imperiled vertebrate taxa. Increased mean global atmospheric temperatures, high rates of habitat degradation, and exposure to infectious diseases, such as chytridiomycosis, have contributed to population declines and extinctions of rare and endangered amphibian species. Field-based monitoring of physiological endocrine traits can help determine the sub-lethal effects of environmental stressors and provide early alerts when populations are chronically stressed. Recent advances in amphibian stress endocrinology include the development and use of non-invasive methods to quantify the glucocorticoid, or stress biomarker, corticosterone. Non-invasive methods, such as …

Water‐Borne And Plasma Corticosterone Are Not Correlated In Spotted Salamanders, Alice R. Millikin, Sarah K. Woodley, Drew R. Davis, Ignacio T. Moore, James T. Anderson

School of Earth, Environmental, & Marine Sciences Faculty Publications

Water‐borne hormone measurement is a noninvasive method suitable for amphibians of all sizes that are otherwise difficult to sample. For this method, containment‐water is assayed for hormones released by the animal. Originally developed in fish, the method has expanded to amphibians, but requires additional species‐specific validations. We wanted to determine physiological relevance of water‐borne corticosterone in spotted salamanders (Ambystoma maculatum) by comparing concentrations to those taken using established corticosterone sampling methods, such as plasma. Using a mixture of field and laboratory studies, we compared water‐borne corticosterone levels to other traditional methods of sampling corticosterone for spotted salamander larvae, metamorphs, and …

Investigations Of Aerobic Methane Oxidation In Two Marine Seep Environments: Part 1—Chemical Kinetics, Eric W. Chan, Allan M. Shiller, Dongjoo J. Joung, Eleanor C. Arrington, David L. Valentine, Molly C. Redmond, John A. Breier, Scott A. Socolofsky, John D. Kessler

School of Earth, Environmental, & Marine Sciences Faculty Publications

Microbial aerobic oxidation is known to be a significant sink of marine methane (CH4), contributing to the relatively minor atmospheric release of this greenhouse gas over vast stretches of the ocean. However, the chemical kinetics of aerobic CH4 oxidation are not well established, making it difficult to predict and assess the extent that CH4 is oxidized in seawater following seafloor release. Here we investigate the kinetics of aerobic CH4 oxidation using mesocosm incubations of fresh seawater samples collected from seep fields in Hudson Canyon, U.S. Atlantic Margin and MC118, Gulf of Mexico to gain a fundamental chemical understanding of this …

The Peculiar Nature Of Florida’S Sandhill Wetlands, Ponds & Lakes— Their Ecohydrology, Relationship With The Regional Aquifer & Importance Within The Landscape., Renae Starr Nowicki

USF Tampa Graduate Theses and Dissertations

This dissertation explores the ecohydrology of Florida’s peculiar and poorly studied sandhill wetland and water features, particularly those located in west-central Florida. The primary research goals include: compilation and summarization of the available ecohydrologic information for features across Florida; comparison of water level and water geochemistry data between sandhill wetlands and waters and the regional aquifer to provide evidence of regional hydrologic control; and use of geophysical applications to examine the hydraulic connections between sandhill wetlands and waters and the regional aquifer.

From this research, a natural history of sandhill wetland and water ecohydrology is presented, highlighting: the differences between …

Mapping Crustal Shear Wave Velocity Structure And Radial Anisotropy Beneath West Antarctica Using Seismic Ambient Noise, J. P. O'Donnell, Audrey D. Huerta, J. Paul Winberry

All Faculty Scholarship for the College of the Sciences

Using 8- to 25-s-period Rayleigh and Love wave phase velocity dispersion data extracted from seismic ambient noise, we (i) model the 3-D shear wave velocity structure of the West Antarctic crust and (ii) map variations in crustal radial anisotropy. Enhanced regional resolution is offered by the UK Antarctic Seismic Network. In the West Antarctic Rift System (WARS), a ridge of crust ∼26–30km thick extending south from Marie Byrd Land separates domains of more extended crust (∼22km thick) in the Ross and Amundsen Sea Embayments, suggesting along-strike variability in the Cenozoic evolution of the WARS. The southern margin of the WARS …

Residential Household Yard Care Practices Along Urban-Exurban Gradients In Six Climatically-Diverse U.S. Metropolitan Areas, Dexter H. Locke, Colin Polsky, J. Morgan Grove, Peter M. Groffman, Kristen C. Nelson, Kelli L. Larson, Jeannine Cavender-Bares, James B. Heffernan, Rinku Roy Chowdhury, Sarah E. Hobbie, Neil D. Bettez, Sharon J. Hall, Christopher Neill, Laura Ogden, Jarlath O'Neil-Dunne

Publications and Research

Residential land is expanding in the United States, and lawn now covers more area than the country’s leading irrigated crop by area. Given that lawns are widespread across diverse climatic regions and there is rising concern about the environmental impacts associated with their management, there is a clear need to understand the geographic variation, drivers, and outcomes of common yard care practices. We hypothesized that 1) income, age, and the number of neighbors known by name will be positively associated with the odds of having irrigated, fertilized, or applied pesticides in the last year, 2) irrigation, fertilization, and pesticide application …

The Potential Of Radium-224 As A Tracer Of Timescales Of Gulf Of Mexico Crude Oil Exposure To The Marine Environment, Matthew T. Kurpiel

Electronic Theses and Dissertations

Petroleum pollution in the marine environment can be deleterious to coastal and marine ecosystems and can have sustained effects for years. While oil slicks on the surface of the ocean are tracked with relative ease using satellite-based technology, deep sea, neutrally-buoyant hydrocarbon plumes remain exceedingly difficult to track. We provide evidence for the utility of Ra-224 as a potential hydrocarbon tracer to determine the marine exposure time of crude oil. We employed time course incubations to constrain a time dependent Ra-224 release signature and tested a variety of timescales, temporal resolutions, oil sources, seawater, and experimental treatments to determine potential …

Quantifying Ocean Acidification In The Geologic Record Using The B/Ca Ratio Of Planktic Foraminifera Shells, Laura Haynes

Sustainability Seminar Series

56 million years ago, the Earth underwent a rapid climate change event called the “Paleocene Eocene Thermal Maximum” (PETM). Sedimentary records show that a massive amount of carbon was released into the atmosphere, causing ocean acidification, warming, and a widespread extinction of deep-sea organisms. Reconstructing the source and amount of carbon released during the PETM has been a major focus for paleoclimatologists as we seek to understand how the Earth system will respond to modern carbon emissions and warming. To help quantify ocean acidification at the PETM, we are using the boron content (the B/Ca ratio) of the shells of …

Isotopic Palaeoecology Of Northern Great Plains Bison During The Holocene, Gaimi Davies, Blake Mccann, Jay Sturdevant, Fern Swenson, Igor V. Ovtchinnikov

Biology Faculty Publications

Bison (Bison bison) are one of the few terrestrial megafauna to survive the transition into the Holocene and provide a unique opportunity to study a species on a broad spatiotemporal scale. Today, bison are primarily managed in small and isolated herds with little known about their ancestral ecology. We studied the carbon and nitrogen isotopes of Northern Great Plains bison from the terminal Pleistocene and throughout the Holocene to gain insight into their paleoecology. This time span is contemporary with the first population bottleneck experienced by bison at the end of the Pleistocene and includes the second bottleneck …

Seismic Evidence For Significant Melt Beneath The Long Valley Caldera, California, Usa, Ashton F. Flinders, David R. Shelly, Philip B. Dawson, David P. Hill, Barbara Tripoli, Yang Shen

United States Geological Survey: Staff Publications

A little more than 760 ka ago, a supervolcano on the eastern edge of California (United States) underwent one of North America’s largest Quaternary explosive eruptions. Over this ~6-day-long eruption, pyroclastic flows blanketed the surrounding ~50 km with more than 1400 km3 of the now-iconic Bishop Tuff, with ashfall reaching as far east as Nebraska. Collapse of the volcano’s magma reservoir created the restless Long Valley Caldera. Although no rhyolitic eruptions have occurred in 100 k.y., beginning in 1978, ongoing uplift suggests new magma may have intruded into the reservoir. Alternatively, the reservoir could be approaching final crystallization, with present-day …

Land Surface Temperature Variability Across India: A Remote Sensing Satellite Perspective, Satya Prakash, Hamidreza Norouzi

Publications and Research

Land surface temperature (LST) plays a key role in the surface energy budget computation and land surface process studies. The Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the Aqua and Terra satellites provide comprehensive global LST estimates at a fine spatial resolution. The MODIS products were recently upgraded to Collection 6, and shown to be more accurate than its predecessor Collection 5 products. In this study, LST and its variability have been examined across India from Collection 6 of the Aqua MODIS data at 0.05° spatial resolution for the period of 2003 to 2017. All-India mean LST characteristics show distinctive …

Comparison Of Extraction Methods For Recovering Ancient Microbial Dna From Paleofeces, Richard W. Hagan, Courtney A. Hofman, Alexander Hübner, Karl Reinhard, Stephanie Schnorr, Cecil M. Lewis Jr., Krithivasan Sankaranarayanan, Christina G. Warinner

Anthropology Faculty Research

Objectives Paleofeces are valuable to archeologists and evolutionary biologists for their potential to yield health, dietary, and host information. As a rich source of preserved biomolecules from host‐associated microorganisms, they can also provide insights into the recent evolution and changing ecology of the gut microbiome. However, there is currently no standard method for DNA extraction from paleofeces, which combine the dual challenges of complex biological composition and degraded DNA. Due to the scarcity and relatively poor preservation of paleofeces when compared with other archeological remains, it is important to use efficient methods that maximize ancient DNA (aDNA) recovery while also …

Early Anthropoid Femora Reveal Divergent Adaptive Trajectories In Catarrhine Hind-Limb Evolution, Sergio Almecija, Melissa Tallman, Hesham M. Sallam, John G. Fleagle, Ashley S. Hammond, Erik R. Seiffert

Peer Reviewed Articles

The divergence of crown catarrhines—i.e., the split of cercopithecoids (Old World monkeys) from hominoids (apes and humans)—is a poorly understood phase in our shared evolutionary history with other primates. The two groups differ in the anatomy of the hip joint, a pattern that has been linked to their locomotor strategies: relatively restricted motion in cercopithecoids vs. more eclectic movements in hominoids. Here we take advantage of the first well-preserved proximal femur of the early Oligocene stem catarrhine Aegyptopithecus to investigate the evolution of this anatomical region using 3D morphometric and phylogenetically-informed evolutionary analyses. Our analyses reveal that cercopithecoids and hominoids …

Uwrl Hosts Awra Conference Tour, Utah Water Research Laboratory

News

The Utah Water Research Laboratory recently had the opportunity to host AWRA Conference attendees on a laboratory tour.

Investigations Of Aerobic Methane Oxidation In Two Marine Seep Environments: Part 2—Isotopic Kinetics, Eric W. Chan, Allan M. Shiller, Dongjoo J. Joung, Eleanor C. Arrington, David L. Valentine, Molly C. Redmond, John A. Breier, Scott A. Socolofsky, John D. Kessler

School of Earth, Environmental, & Marine Sciences Faculty Publications

During aerobic oxidation of methane (CH4) in seawater, a process which mitigates atmospheric emissions, the 12C‐isotopologue reacts with a slightly greater rate constant than the 13C‐isotopologue, leaving the residual CH4 isotopically fractionated. Prior studies have attempted to exploit this systematic isotopic fractionation from methane oxidation to quantify the extent that a CH4 pool has been oxidized in seawater. However, cultivation‐based studies have suggested that isotopic fractionation fundamentally changes as a microbial population blooms in response to an influx of reactive substrates. Using a systematic mesocosm incubation study with recently collected seawater, here we investigate the fundamental isotopic kinetics of aerobic …

Reinterpreting The Tectonic Model Of The Southern Part Of The Taconic Orogeny Through A Provenance Study Of Late Ordovician Sandstones, Juan Carlos Guerrero

LSU Master's Theses

A provenance study of quartz arenites that stratigraphically are closely associated with major Ordovician K-bentonites has been conducted in order to further our understanding of the tectonic setting of eastern Laurentia during the Late Ordovician. Using laser ablation ICP-MS, detrital zircons separated from Ordovician sandstone samples in the southeastern Appalachian Mountains (Virginia to Alabama) were dated using U-Pb geochronology. Analytical results show three dominate age ranges for the zircons from these sandstones: ~440-490 Ma, ~900-1300 Ma, and ~1300-1500 Ma. In addition, some zircon ages grouped into older ranges of ~1600-1800 Ma, ~1800-1900 Ma, and ~2600-2800 Ma. Zircon ages from ~900-2800 …