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Articles 1 - 16 of 16
Full-Text Articles in Geology
Geol 112: Hazards, Risks Of Earthquakes And Volcanoes Textbook Alternatives, Donald Reed
Geol 112: Hazards, Risks Of Earthquakes And Volcanoes Textbook Alternatives, Donald Reed
Donald Reed
Poster summarizing cost saving textbook alternatives for GEOL 112: Hazards, Risks of Earthquakes and Volcanoes.
Topographic Control Of Asynchronous Glacial Advances: A Case Study From Annapurna, Nepal, B. Pratt-Sitaula, D. W. Burbank, A. M. Heimsath, Neil Humphrey, M. Oskin, J. Putkonen
Topographic Control Of Asynchronous Glacial Advances: A Case Study From Annapurna, Nepal, B. Pratt-Sitaula, D. W. Burbank, A. M. Heimsath, Neil Humphrey, M. Oskin, J. Putkonen
Neil Humphrey
Differences in the timing of glacial advances, which are commonly attributed to climatic changes, can be due to variations in valley topography. Cosmogenic Be-10 dates from 24 glacial moraine boulders in 5 valleys define two age populations, late-glacial and early Holocene. Moraine ages correlate with paleoglacier valley hypsometries. Moraines in valleys with lower maximum altitudes date to the late-glacial, whereas those in valleys with higher maximum altitudes are early Holocene. Two valleys with similar equilibrium-line altitudes (ELAs), but contrasting ages, are aspect, such that spatial differences in climate can be excluded. A glacial mass-balance cellular automata model of these two …
The Quasi-Static Deformation, Failure, And Fracture Behavior Of Titanium Alloy Gusset Plates Containing Bolt Holes, Therese Hurtuk, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan, Kannan Manigandan, T. Quick
The Quasi-Static Deformation, Failure, And Fracture Behavior Of Titanium Alloy Gusset Plates Containing Bolt Holes, Therese Hurtuk, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan, Kannan Manigandan, T. Quick
Craig Menzemer
In this article, the influence of bolt holes, specifically their number and layout on strength, deformation, and final fracture behavior of titanium alloy gusset plates under the influence of an external load is presented and discussed. Several plates having differences in both the number and layout of the bolt holes were precision machined and then deformed under quasi-static loading. The specific influence of number of bolt holes and their layout on maximum load-carrying capability and even fracture load was determined. The conjoint influence of bolt number, bolt layout pattern, nature of loading, contribution from local stress concentration, and intrinsic microstructural …
The Sedimentary Flux Of Dissolved Rare Earth Elements To The Ocean, April Abbott, Brian Haley, James Mcmanus, Clare Reimers
The Sedimentary Flux Of Dissolved Rare Earth Elements To The Ocean, April Abbott, Brian Haley, James Mcmanus, Clare Reimers
James McManus
We determined pore fluid rare earth element (REE) concentrations in near-surface sediments retrieved from the continental margin off Oregon and California (USA). These sites represent shelf-to-slope settings, which lie above, within, and below the oxygen minimum zone of the Northeast Pacific. The sediments are characterized by varying degrees of net iron reduction, with pore fluids from the shelf sites being generally ferruginous, and the slope sediments having less-pronounced iron reduction zones that originate deeper in the sediment package. REE concentrations show maxima in shallow (upper 2–10 cm) subsurface pore fluids across all sites with concentrations that rise more than two …
The Quasi-Static Deformation, Failure, And Fracture Behavior Of Titanium Alloy Gusset Plates Containing Bolt Holes, Therese Hurtuk, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan, Kannan Manigandan, T. Quick
The Quasi-Static Deformation, Failure, And Fracture Behavior Of Titanium Alloy Gusset Plates Containing Bolt Holes, Therese Hurtuk, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan, Kannan Manigandan, T. Quick
Anil Patnaik
In this article, the influence of bolt holes, specifically their number and layout on strength, deformation, and final fracture behavior of titanium alloy gusset plates under the influence of an external load is presented and discussed. Several plates having differences in both the number and layout of the bolt holes were precision machined and then deformed under quasi-static loading. The specific influence of number of bolt holes and their layout on maximum load-carrying capability and even fracture load was determined. The conjoint influence of bolt number, bolt layout pattern, nature of loading, contribution from local stress concentration, and intrinsic microstructural …
Geochronology Of Hemphillian-Blancan Aged Strata, Guanajuato, Mexico, And Implications For Timing Of The Great American Biotic Interchange, Bart Kowallis, John Flynn, Clarita Nunez, Oscar Carranza-Castaneda, Wade Miller, Carl Swisher, Everett Lindsay
Geochronology Of Hemphillian-Blancan Aged Strata, Guanajuato, Mexico, And Implications For Timing Of The Great American Biotic Interchange, Bart Kowallis, John Flynn, Clarita Nunez, Oscar Carranza-Castaneda, Wade Miller, Carl Swisher, Everett Lindsay
Bart J Kowallis
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 …
Contrasting Silicic Magma Series In Miocene-Pliocene Ash Deposits In The San Miguel De Allende Graben, Guanajuato, Mexico, Eric Christiansen, Bart Kowallis, Aaron Adams, Oscar Carranza-Castaneda, Wade Miller
Contrasting Silicic Magma Series In Miocene-Pliocene Ash Deposits In The San Miguel De Allende Graben, Guanajuato, Mexico, Eric Christiansen, Bart Kowallis, Aaron Adams, Oscar Carranza-Castaneda, Wade Miller
Bart J Kowallis
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 …
Neotectonics Of Major Faults Based On Strain Analysis And U-Th Dating Of Syntectonic Calcite, R. Weinberger, P. Nuriel, John Craddock
Neotectonics Of Major Faults Based On Strain Analysis And U-Th Dating Of Syntectonic Calcite, R. Weinberger, P. Nuriel, John Craddock
John Craddock
No abstract provided.
Stable Isotope Studies Of Paleoenvironment And Paleoclimate From Afar, Ethiopia, Zelalem K. Bedaso
Stable Isotope Studies Of Paleoenvironment And Paleoclimate From Afar, Ethiopia, Zelalem K. Bedaso
Zelalem Bedaso
ABSTRACT The sedimentary deposits of the Hadar Formation at Dikika and the Mount Galili Formation at Galili preserve a wealth of paleoenvironmental and paleoclimatic records spanning the last 5.29 Ma. Stable carbon and oxygen isotopic compositions of herbivore tooth enamel were analyzed for more than 600 specimens of 15 different taxa from 10 stratigraphic intervals. The application of carbon and oxygen isotopes here aims principally at reconstructing shifts in the relative abundance of C4 grasses, and its implications for climate indicators including temperature, aridity, and seasonality. The full range of δ13Cenamel values throughout the Plio-Pleistocene signifies a wide range of …
Late Pleistocene Glacial History And Magnetic Chronostratigraphy, Western Adirondack Borderland, New York, Donald Pair
Late Pleistocene Glacial History And Magnetic Chronostratigraphy, Western Adirondack Borderland, New York, Donald Pair
Donald L. Pair
New lines of evidence from the western Adirondack borderland have been employed to assess the style of deglaciation and reconstruct the nature and timing of associated proglacial lacustrine and marine (Champlain Sea) events. Contrasting styles of deglaciation, controlled primarily by water depth, resulted in landfast ice withdrawing gradually on the northern slope of the Adirondacks while actively calving ice, retreating rapidly in the deep water of Lake Iroquois, quickly evacuated the western St. Lawrence Lowland of ice. The extent of ice retreat from the western St. Lawrence Lowland during the life of Lake Iroquois has been estimated on the basis …
Communicating The Science Of Igcp 591 To The Public, Lewandowski J. Katherine
Communicating The Science Of Igcp 591 To The Public, Lewandowski J. Katherine
Katherine J. Lewandowski
Selling the broader impacts of science to funding agencies has become a necessity in a time when competition for grant money is high. While involving students in research is still important for maintaining a pipeline of trained scientists, the bar has been raised and it is increasingly incumbent on us to communicate to the public what is so important about our work. To be competitive in the search for funds, there must be a plan for the science funded to be disseminated to the public. The education and outreach plan for IGCP 591 attempts to appeal to this broader audience …
Longitudinal Profile And Sediment Mobility As Geomorphic Tools To Interpret The History Of A Fluviokarst Stream System, John Woodside, Eric Peterson, Toby Dogwiler
Longitudinal Profile And Sediment Mobility As Geomorphic Tools To Interpret The History Of A Fluviokarst Stream System, John Woodside, Eric Peterson, Toby Dogwiler
Eric Wade Peterson
The complex drainage systems within karst settings can result in atypical longitudinal profiles. Features, such as cave entrances, can be expressed as anomalous ‘bumps’ in the longitudinal profile of a stream if downcutting has continued upstream of the area in which the water is pirated to the subsurface. Horn Hollow, a fluviokarst valley located in Carter Caves State Park Resort in northeastern Kentucky, was examined for these types of features. The objectives of this study were to determine if sediment mobility can be used as a proxy for anomalous areas along the profile of the valley and if detailed cross-sections …
Three-Dimensional Geologic Model Of The Pecatonica Gas Storage Field, Winnebago County, Illinois, Nicole Kron, David Malone, Eric Peterson
Three-Dimensional Geologic Model Of The Pecatonica Gas Storage Field, Winnebago County, Illinois, Nicole Kron, David Malone, Eric Peterson
Eric Wade Peterson
Stratigraphy And Porosity Modeling Of Southern Centeral Illinois Chester (Upper Missisippian) Series Sandstones Usng Petrel, Darren Kimple, Eric Peterson, David Malone
Stratigraphy And Porosity Modeling Of Southern Centeral Illinois Chester (Upper Missisippian) Series Sandstones Usng Petrel, Darren Kimple, Eric Peterson, David Malone
Eric Wade Peterson
Identification Of Potential Vertical Gas Migration Pathways Above Gas Storage Reservoirs, Eric Peterson, Lauren Martin, David Malone
Identification Of Potential Vertical Gas Migration Pathways Above Gas Storage Reservoirs, Eric Peterson, Lauren Martin, David Malone
Eric Wade Peterson
Rock Strength Along A Fluvial Transect Of The Colorado Plateau - Quantifying A Fundamental Control On Geomorphology, Natalie Bursztyn, Joel Pederson
Rock Strength Along A Fluvial Transect Of The Colorado Plateau - Quantifying A Fundamental Control On Geomorphology, Natalie Bursztyn, Joel Pederson
Natalie Bursztyn
Bedrock strength is a key parameter that influences slope stability, landscape erosion, and fluvial incision. Yet, it is often ignored or indirectly constrained in studies of landscape evolution, as with the K erodibility parameter in stream-power models. Empirical datasets of rock strength suited to address geomorphic questions are rare, in part because of the difficulty in measuring those rocks at Earth's surface that are heterolithic, weak, or poorly exposed. Here we present a large dataset of measured bedrock strength organized by rock units exposed along the length of the trunk Green–Colorado River through the iconic Colorado Plateau of the western …