Earth Sciences Commons^™

Gis Aided Archaeological Research Of El Camino Real De Los Tejas With Focus On The Landscape And River Crossings Along El Camino Carretera., Jeffrey M. Williams

Faculty Publications

Many generations of indigenous pathways through the forests of eastern Texas have their origins obscured in antiquity. Utilized by early European explorers, these pathways became modified through heavy use and the expansions and improvements needed to accommodate easy passage of European horses and carts and finally the heavy wagons of Anglo-American settlers. The first road through Texas, El Camino Real de Los Tejas, utilized portions of these early trails.

El Camino Carretera (known as the cart road) is an early segment of El Camino Real de los Tejas that crossed the Sabine River at the boundary between Texas and Louisiana. …

Bedrock Channel Geometry Along An Orographic Rainfall Gradient In The Upper Marsyandi River Valley In Central Nepal, William Craddock, Douglas Burbank, Bodo Bookhagen, Emmanuel Gabet

Faculty Publications

Pronounced rainfall gradients combined with spatially uniform exhumation of rocks at Quaternary timescales and uniform rock strength make the upper Marsyandi River valley in central Nepal a useful natural laboratory in which to explore variations in bedrock channel width. We focus on small catchments (0.6–12.4 km2) along a more than tenfold gradient in monsoon rainfall. Rainfall data are gathered from a dense weather network and calibrated satellite observations, the pattern of Quaternary exhumation is inferred from apatite fission track cooling ages, and rock compressive strength is measured in the field. Bedrock channel widths, surveyed at high scour indicators, scale as …

Sea Surface Pco2‐Sst Relationships Across A Cold‐Core Cyclonic Eddy: Implications For Understanding Regional Variability And Air‐Sea Gas Exchange, Feizhou Chen, Wei‐Jun Cai, Claudia R. Benitez-Nelson, Yongchen Wang

Faculty Publications

[1] This study is designed to improve the understanding of how biologically productive, cold‐core cyclonic eddies affect sea surface pCO2 in the lee of the main Hawaiian Islands in the subtropical North Pacific Gyre. We identified three unique relationships between pCO2 and sea surface temperature (SST). A positive correlation between pCO2 and SST was observed in the waters surrounding the eddy suggesting surface CO2 is controlled primarily by thermodynamics. In contrast, a negative relationship was observed within the eddy core as a result of the upwelling of CO2‐enriched subsurface waters. A third relationship existed throughout the rest …

Hikorocodium Endo Is Not An Alga But An Inozoid Sponge, J. Keith Rigby, Baba Senowbari-Daryan

Faculty Publications

The genus Hikorocodium, with the type species Hikorocodium elegantae from the Permian of Japan, was described originally as a codiacean alga by Endo. It is not a codiacean alga but an inozoid sponge of the family Preperonidellidae. Several fossils described later by Endo and other authors as H. elegantae should be assigned to different inozoid sponge taxa. Specimens of H. fertiliz, described by Endo from the Jurassic of Japan, are also sponge fragments. The taxonomic positions of H. transversum Endo and H. kuramotoi Nakamura, as sponges or

Particulate Organic Carbon Fluxes Along Upwelling‐Dominated Continental Margins: Rates And Mechanisms, Robert Thunell, Claudia R. Benitez-Nelson, Ramon Varela, Yrene Astor, Frank Muller‐Karger

Faculty Publications

[1] Time series sediment trap samples were used to examine the rates and mechanisms of particulate organic carbon (POC) flux at three continental margin locations, Santa Barbara Basin, Cariaco Basin, and Guaymas Basin, marked by seasonal upwelling and high primary production. The mean POC flux in Santa Barbara Basin (0.096 g m−2 d−1) is nearly twice that of Cariaco Basin and 4 times higher than that in Guaymas Basin, with all three sites having POC fluxes significantly higher than the open ocean average (0.007 g m−2 d−1). In Cariaco Basin, the only site with available primary production numbers, there is …

Submarine Volcanic Morphology Of The Western Galapagos Based On Em300 Bathymetry And Mr1 Side-Scan Sonar, Jennifer B. Glass, D J. Fornari, Hillary F. Hall, Allison A. Cougan, Heidi A. Berkenbosch, Mark L. Holmes, Scott M. White, Giorgio De La Torre

Faculty Publications

A compilation of high-resolution EM300 multibeam bathymetric and existing MR1 side-scan sonar data was used to investigate the volcanic morphology of the flanks of the western Galapagos Islands. The data portray an assortment of constructional volcanic features on the shallow to deep submarine flanks of Fernandina, Isabela, and Santiago Islands, including rift zones and groups of cones that are considered to be the primary elements in constructing the archipelagic apron. Ten submarine rift zones were mapped, ranging in length from 5 to 20 km, comparable in length to western Canary Island rift zones but significantly shorter than Hawaiian submarine rift …

Application Of The Empirical Mode Decomposition And Hilbert-Huang Transform To Seismic Reflection Data, Bradley M. Battista, Camelia C. Knapp, Tom Mcgee, Vaughn Goebel

Faculty Publications

Advancements in signal processing may allow for improved imaging and analysis of complex geologic targets found in seismic reflection data. A recent contribution to signal processing is the empirical mode decomposition (EMD) which combines with the Hilbert transform as the Hilbert- Huang transform (HHT). The EMD empirically reduces a time series to several subsignals, each of which is input to the same time-frequency environment via the Hilbert transform. The HHT allows for signals describing stochastic or astochastic processes to be analyzed using instantaneous attributes in the time-frequency domain. The HHT is applied herein to seismic reflection data to: (1) assess …

Biogeography And The Cambrian Radiation Of Arachnomorph Arthropods, Jonathan R. Hendricks, Bruce S. Lieberman

Faculty Publications

Biogeographic patterns in primarily Cambrian arachnomorph taxa are investigated using a recently constructed phylogenetic hypothesis in order to explore the biogeographic context of the Cambrian radiation. A modified version of Brooks Parsimony Analysis is employed to elucidate patterns of vicariance and geodispersal in taxa from six regions (Laurentia, Baltica, Siberia, Australia, Africa and China). Well resolved vicariance and geodispersal trees are very similar and reconstruct Laurentia and China as sister areas. This close area relationship between Laurentia and China provides extensive evidence for congruent vicariance and range expansion in Cambrian arachnomorphs, while data from trilobites do not show this pattern. …

A New View Of Ridge Segmentation And Near-Axis Volcanism At The East Pacific Rise, 8˚–12˚N, From Em300 Multibeam Bathymetry, Scott M. White, Rachel M. Haymon, S M. Carbotte

Faculty Publications

New, high-resolution bathymetry for the East Pacific Rise between 8˚N and 12˚N was collected over a6 km wide swath centered on the ridge axis using the 30 kHz Simrad EM300 multibeam system. Thecoverage area corresponds latitudinally to the designated Ridge2000 Integrated Studies Site (ISS) for fastspreading ridges. The EM300 data, gridded at 30 m latitude by 50 m longitude, represent a greater than 4Ximprovement in horizontal resolution over previously available multibeam data and a 2X improvement indepth resolution. The new bathymetry was used to update the locations and hierarchy of ridge offsets forthis area. Among the many applications for this …

Subtidal Inner Shelf Currents Off Cartagena De Indias, Caribbean Coast Of Colombia, Mauro Maza, George Voulgaris, Bulusu Subrahmanyam

Faculty Publications

Seasonal trends in inner shelf subtidal circulation off the coast of Cartagena de Indias, Colombia, are examined through the analysis of current profiles, hydrographic, meteorological and satellite data collected from 1999 to 2002. During the dry season (December–April) the water column is well-mixed and along-shelf currents flow southwestward following the steady trade winds. In the rainy season (May –November) the water column experiences continuous events of stratification and the along-shelf currents flow northeastward, opposing the weak southwestward winds. In the dry season the along shelfcirculation is mostly driven by wind forcing, while in the rainy season, the circulation is set …

A Nd Isotopic Study Of Southern Sourced Waters And Indonesian Throughflow At Intermediate Depths In The Cenozoic Indian Ocean, Ellen E. Martin, Howie Scher

Faculty Publications

We present Nd isotopic data for fossil fish teeth recovered from the past 40 m.y. at ODP Site 757, currentlylocated at 1650m water depth on the Ninetyeast Ridge in the Indian Ocean. Although Site 757 sits in a regionstrongly influenced by weathering inputs from the Himalayas and volcanic inputs from the Indonesian arc, the pattern of Nd isotopic variations does not appear to respond to these potential sources of Nd. Instead, secular variations correlate to changes in the composition of intermediate to deep water masses bathing thesite and circulation patterns in the Indian Ocean. From ~40 to 10 Ma, eNd …

Long-Term Volumetric Eruption Rates And Magma Budgets, Scott M. White, Joy A. Crisp, Frank J. Spera

Faculty Publications

A global compilation of 170 time-averaged volumetric volcanic output rates (Qe) is evaluated in terms of composition and petrotectonic setting to advance the understanding of long-term rates of magma generation and eruption on Earth. Repose periods between successive eruptions at a given site and intrusive:extrusive ratios were compiled for selected volcanic centers where long-term (>104 years) data were available. More silicic compositions, rhyolites and andesites, have a more limited range of eruption rates than basalts. Even when high Qe values contributed by flood basalts (9 ± 2 10[1]1 km3/yr) are removed, there is a trend in decreasing average Qe …

Contrasting Silicic Magma Series In Miocene-Pliocene Ash Deposits In The San Miguel De Allende Graben, Guanajuato, Mexico, Eric H. Christiansen, Bart J. Kowallis, Aaron J. Adams, Oscar Carranza-Castaneda, Wade E. Miller

Faculty Publications

The San Miguel de Allende graben, Guanajuato, Mexico, contains numerous rhyolitic volcanic ash beds. Electron microprobe and x-ray fluorescence analyses of glass shards from 14 localities, combined with mineralogic, stratigraphic, radiometric, and paleomagnetic data, allow us to correlate the ash beds (and the intervening sedimentary strata and fossils), understand the timing of volcanism, date the age of extension, and better understand the tectonic and volcanic evolution of central Mexico. Our analyses reveal that at least six separate eruptions of rhyolitic ash occurred during the Late Miocene and Pliocene (5-3 Ma) while the San Miguel Allende basin was subsiding. The fallout …

Cross-Shore Variation Of Wind-Driven Flows On The Inner Shelf In Long Bay, South Carolina, United States, Benjamin T. Gutierrez, George Voulgaris, Paul A. Work

Faculty Publications

The cross-shore structure of subtidal flows on the inner shelf (7 to 12 m water depth) of Long Bay, South Carolina, a concave-shaped bay, is examined through the analysis of nearly 80 days of near-bed (1.7–2.2 m above bottom) current observations acquired during the spring and fall of 2001. In the spring and under northeastward winds (upwelling favorable) a two-layered flow was observed at depths greater than 10 m, while closer to the shore the currents were aligned with the wind. The two-layered flow is attributed to the presence of stratification, which has been observed under similar conditions in the …

Prediction Of Sediment-Bound Nutrient Delivery From Semi-Arid California Watersheds, Emmanuel Gabet, Noah Fierer, Oliver Chadwick

Faculty Publications

Soil carbon (C), nitrogen (N), and phosphorus (P) are lost from hillslopes in particulate forms through soil erosion. The fate of the eroded C (e.g., sequestration or oxidation) may affect the global C budget, and delivery of N and P to waterbodies can lead to eutrophication. Whereas the magnitude of particulate nutrient losses may be similar to or greater than dissolved losses, it is rarely estimated. We couple a sediment delivery model with measurements of C, N, and P in soil to account explicitly for hillslope sediment transport processes that yield sediment-bound nutrients to fluvial networks. The model is applied …

Geochronology Of Hemphillian-Blancan Aged Strata, Guanajuato, Mexico, And Implications For Timing Of The Great American Biotic Interchange, Bart J. Kowallis, John J. Flynn, Clarita Nunez, Oscar Carranza-Castaneda, Wade E. Miller, Carl C. Swisher Iii, Everett Lindsay

Faculty Publications

We present new geochronologic magnetostratigraphy, fission-track and 40Ar/39Ar radioisotopic dates, biostratigraphy)bdata constraining the age of three separate sequences and a composite section from Guanajuato, Mexico. Those data make this one of the most complete and precisely age-calibrated sequences in North America spanning the Hemphillian/Blancan North American Land Mammal “Age” (NALMA) boundary interval, and the data further constrain the timing and pattern of the Great American Biotic Interchange (GABI). In total, 196 samples (77 sites) were used to construct the magnetic polarity stratigraphies, with eight fission-track analyses and four new 40Ar/39Ar radioisotopic dates. The sections sampled are possibly latest Miocene to …

Monsoon-Driven Biogeochemical Processes In The Arabian Sea, Jerry D. Wiggert, Raleigh Hood, Karl Banse, John Kindle

Faculty Publications

Although it is nominally a tropical locale, the semiannual wind reversals associated with the Monsoon system of the Arabian Sea result annually in two distinct periods of elevated biological activity. While in both cases monsoonal forcing drives surface layer nutrient enrichment that supports increased rates of primary productivity, fundamentally different entrainment mechanisms are operating in summer (Southwest) and winter (Northeast) Monsoons. Moreover, the intervening intermonsoon periods, during which the region relaxes toward oligotrophic conditions more typical of tropical environments, provide a stark contrast to the dynamic biogeochemical activity of the monsoons. The resulting spatial and temporal variability is great and …

The Effects Of Satellite-Derived Vegetation Cover Variability On Simulated Land–Atmosphere Interactions In The Nams, Toshi Matsui, Venkataraman Lakshmi, Eric Small

Faculty Publications

Substantial evolution of Normalized Difference Vegetation Index (NVDI)-derived vegetation cover (Fg)exists in the southwestern United States and Mexico. The intraseasonal and wet-/dry-year fluctuations of Fgare linked to observed precipitation in the North American monsoon system (NAMS). The manner in whichthe spatial and temporal variability of Fg influences the land–atmosphere energy and moisture fluxes, andassociated likelihood of moist convection in the NAMS regions, is examined. For this, the regional climatemodel (RCM) is employed, with three different Fg boundary conditions to examine the influence ofintraseasonal and wet-/dry-year vegetation variability. Results show that a strong link exists between evaporativefraction (EF), surface temperature, and …

New Standards For Reducing Gravity Data: The North American Gravity Database, William J. Hinze, Carlos Aiken, John Brozena, Bernard Coakley, David Dater, Guy Flanagan, Rene Forsberg, Thomas Hildenbrand, G. Randy Keller, James N. Kellogg, Robert Kucks, Xiong Li, Andre Mainville, Robert Morin, Mark Pilkington, Donald Plouff, Dhananjay Ravat, Daniel Roman, Jamie Urrutia-Fucugauchi, Marc Veronneau, Michael Webring, Daniel Winester

Faculty Publications

The North American gravity database as well as databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revising procedures for calculating gravity anomalies, taking into account our enhanced computational power, improved terrain databases and datums, and increased interest in more accurately defining long-wavelength anomaly components. Users of the databases may note minor differences between previous and revised database values as a result of these procedures. Generally, the differences do not impact the interpretation of local anomalies but do improve regional anomaly studies. The most …

Analysis Of Process Controls In Land Surface Hydrological Cycle Over The Continental United States, Tajdarul Hassan Syed, Venkataraman Lakshmi, Evan Paleologos, Dag Lohmann, Kenneth Mitchell, James S. Famiglietti

Faculty Publications

The paper uses two years (1997–1999) of data from the North American Land Data Assimilation System at National Centers for Environmental Prediction to analyze the variability of physical variables contributing to the hydrological cycle over the conterminous United States. The five hydrological variables considered in this study are precipitation, top layer soil moisture (0–10 cm), total soil moisture (0–200 cm), runoff, and potential evaporation. There are two specific analyses carried out in this paper. In the first case the principal components of the hydrological cycle are examined with respect to the loadings of the individual variables. This helps to ascertain …

An Unusually Large Aulocopella Winnipegensis And Associated Demosponges From The Upper Ordovician Beaverfoot Formation, Southeastern British Columbia, J. Keith Rigby, Paul A. Johnston

Faculty Publications

An unusually large specimen of the rare digitate to bladed Aulocopella winnipegensis Rauff and three relatively normal sized specimens of ashtray-shaped Hudsonospongia? sp. constitute the first record of demosponges from the Upper Ordovician Beaverfoot Formation in southeastern British Columbia and the first record of these taxa from western Canada. Gross form and canal structure are well preserved, but dolomitization and (or) coarse microsphaeroidal silicification have obliterated spicules and other structural details. We interpret these sponges as epifaunal recliners, without means of attachment to the substrate, a life mode rarely encountered in the modern sponge biota.

Geomorphic Analysis Of Tidal Creek Networks, Karyn Inez Novakowski, Raymond Torres, L Robert Gardner, George Voulgaris

Faculty Publications

The purpose of this study is to determine if concepts in terrestrial channel network analysis provide insight on intertidal creek network development and to present new metrics for their analysis. We delineated creek network geometry using high-resolution digital images of intertidal marsh near Georgetown, South Carolina. Analyses reveal that intertidal creek networks may be topologically random. Length-area relationships suggest that salt marsh and terrestrial networks have similar scaling properties, although the marsh networks are more elongate than terrestrial networks. To account for recurrent water exchange between creek basins at high tide, we propose that the landscape unit of geomorphic analyses …

Effects Of Low Tide Rainfall On Intertidal Zone Material Cycling, Raymond Torres, Miguel A. Goni, George Voulgaris, Charles R. Lovell, James T. Morris

Faculty Publications

Sediment transport by rainfall-runoff processes is well documented for terrestrial landscapes but few studies have focused on rainfall-runoff effects in intertidal areas. Here we present geochemical analyses performed on sediment samples collected during low tide irrigation experiments, and tidal channel turbidity measurements taken during natural rainfall over North Inlet Marsh, South Carolina. Order of magnitude approximations indicate that a single 10 minute storm may entrain 8-15% of the local annual average sediment accumulation. This rainfall-entrained material is enriched in organic nitrogen and marine algal matter, and therefore of high nutritional quality.

Runoff And Sediment Losses From Annual And Unusual Storm Events From The Alto Experimental Watersheds, Texas: 23 Years After Silvicultural Treatments, Matthew W. Mcbroom, R Scott Beasley, Mingteh Chang, Brian Gowin, George G. Ice

Faculty Publications

Evaluating the potential impacts of intensive silvicultural practices on water quality is critical for establishing the long-term sustainability of contemporary forest management practices. From 1979 to 1985, a study involving nine small (~2.5 ha) forested watersheds was conducted near Alto, Texas in the upper western Gulf-Coastal Plain to evaluate the impacts then-current silvicultural practices on water quality. In the years following the study, silvicultural Best Management Practices (BMPs) including Streamside Management Zones (SMZs) and other erosion control practices evolved and questions arose about the applicability of earlier results to current practices. In 1999, these same watersheds were reinstrumented to evaluate …

A Stochastic Sediment Delivery Model For A Steep Mediterranean Landscape, Emmanuel Gabet, Thomas Dunne

Faculty Publications

It is a truism in geomorphology that climatic events operate on a landscape to drive sediment transport processes, yet few investigations have formally linked climate and terrain characteristics with geomorphological processes. In this study, we incorporate sediment transport equations derived from fieldwork into a computer model that predicts the delivery of sediment from hillslopes in a steep Mediterranean landscape near Santa Barbara, California. The sediment transport equations are driven by rainstorms and fires that are stochastically generated from probability distributions. The model is used to compare the rates and processes of sediment delivery under two vegetation types: coastal sage scrub …

Links Between Snow Cover, Surface Skin Temperature, And Rainfall Variability In The North American Monsoon System, Toshi Matsui, Venkataraman Lakshmi, Eric Small

Faculty Publications

The influence of land–atmosphere interactions on the variability of the North American monsoon system(NAMS) is investigated using the Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder(TOVS) Pathfinder, the Climate Prediction Center (CPC) gauge precipitation, and observed snow water equivalent(SWE). Three hypotheses are tested regarding the connection between land surface variables and precipitationin the NAMS region. First, there is a weak negative correlation between 1 April SWE and subsequent surfacetemperature in the southern Rocky Mountains (SRM) region. However, this connection persists only until Juneand, therefore, cannot directly influence monsoon rainfall in July and August. Second, there is a negativecorrelation between SRM …

Bacteriological Water Quality Of Forested And Pastured Streams Receiving Land-Applied Poultry Litter, Matthew W. Mcbroom, Chang Mingteh, Charles Wells

Faculty Publications

Poultry production is a growing industry in East Texas, generating about 360,000 m tons of broiler litter each year as a by-product for application on pasturelands. Grab samples of fecal coliform (FC) and fecal streptococcus (FS) were collected monthly between March and December 1996 and FC and E-coli samples were collected weekly between July and October 2001 at six sites on the Waffelo and Terrapin Creeks in Nacogdoches County, Texas to assess possible impacts of poultry litter application on bacterial water quality. Sites were grouped by three pairs with each pair consisting of one upstream site in predominantly forested area …

Mercury Concentrations In Streams Of East Texas, Mingteh Chang, Mark C. Cochran, R. Scott Beasley, Matthew W. Mcbroom

Faculty Publications

Recent studies on potential mercury (Hg) contamination of fish from East Texas lakes and waterways have caused concern about mercury levels in East Texas waters. Historical records of Hg concentrations in 33 East Texas streams showed that median concentrations for each stream segment were no different than other U.S. streams. All the means and medians for stream segments having at least 20 recorded measurements were less than Texas (2.4 µg/L) water quality standards. Water samples collected in December 1995 and March 1996 from 6 different stream sites in Nacogdoches County had concentrations similar to historical records. Due to biological magnification, …

Eocene To Miocene Magnetostratigraphy, Biostratigraphy, And Chemostratigraphy At Odp Site 1090 (Sub-Antarctic South Atlantic), J E T Channell, S Galeotti, Ellen E. Martin, K Billups, Howie Scher, J S. Stoner

Faculty Publications

At Ocean Drilling Program (ODP) Site 1090 (lat 42854.89S, long 8854.09E) locatedin a water depth of 3702 m on the Agulhas Ridge in the sub-Antarctic South Atlantic, ~300 m of middle Eocene to middle Miocenesediments were recovered with the advancedpiston corer (APC) and the extendedcore barrel (XCB). U-channel samplesfrom the 70–230 meters composite depth(mcd) interval provide a magnetic polaritystratigraphy that is extended to 380 mcd byshipboard whole-core and discrete sampledata. The magnetostratigraphy can be interpretedby the fit of the polarity-zone patternto the geomagnetic polarity time scale(GPTS) augmented by isotope data andbioevents with documented correlation tothe GPTS. Three normal-polarity subchrons(C5Dr.1n, C7Ar.1n, …

Influence Of A Cyclonic Eddy On Microheterotroph Biomass And Carbon Export In The Lee Of Hawaii, Robert R. Bidigare, Claudia R. Benitez-Nelson, Carrie L. Leonard, Paul D. Quay, Michael L. Parsons, David G. Foley, Michael P. Seki

Faculty Publications

[1] A multi‐platform sampling strategy was used to investigate carbon cycling in a cold‐core eddy that formed in the lee of Hawaii during September 2000. Microheterotroph biomass and 234Th‐derived carbon export rates within the eddy were 2 to 3 times higher than those observed for adjacent waters. If this eddy is representative of other cyclonic eddies that are frequently formed in the lee of Hawaii, then eddy activity may significantly enhance the areal efficiency of the biological pump and facilitate the transfer of organic carbon to organisms inhabiting the mesopelagic and abyssal‐benthic zones of this subtropical ecosystem.