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Articles 5101 - 5130 of 5201
Full-Text Articles in Geology
Mgrre_Thinsections_12-A_18, Mgrre
Mgrre_Thinsections_12-A_30, Mgrre
Mgrre_Thinsections_12-A_49, Mgrre
Mgrre_Thinsections_12-A_50, Mgrre
Mgrre_Thinsections_12-A_57, Mgrre
Mgrre_Thinsections_12-A_1, Mgrre
Mgrre_Thinsections_12-A_56, Mgrre
Mgrre_Thinsections_12-A_3, Mgrre
Mgrre_Thinsections_12-A_8, Mgrre
Mgrre_Thinsections_12-A_12, Mgrre
Mgrre_Thinsections_12-A_20, Mgrre
Mgrre_Thinsections_12-A_14, Mgrre
Mgrre_Thinsections_12-A_78, Mgrre
Coastal Paleogeography Of The Pacific Northwest, Usa, For The Last 12,000 Years Accounting For Three-Dimensional Earth Structure, Jorie Clark, Jay R. Alder, Marisa Borreggine, Jerry X. Mitrovica, Konstantin Latychev
Coastal Paleogeography Of The Pacific Northwest, Usa, For The Last 12,000 Years Accounting For Three-Dimensional Earth Structure, Jorie Clark, Jay R. Alder, Marisa Borreggine, Jerry X. Mitrovica, Konstantin Latychev
United States Geological Survey: Staff Publications
Predictive modeling of submerged archaeological sites requires accurate sea-level predictions in order to reconstruct coastal paleogeography and associated geographic features that may have influenced the locations of occupation sites such as rivers and embayments. Earlier reconstructions of the paleogeography of parts of the western U.S. coast used an assumption of eustatic sea level, but this neglects the large spatial variations in relative sea level (RSL) associated with glacial isostatic adjustment (GIA) and tectonics. Subsequent work using a one-dimensional (1-D) solid Earth model showed that reconstructions that accounted for GIA result in significant differences from those based on eustatic sea level. …
Coastal Paleogeography Of The Pacific Northwest, Usa, For The Last 12,000 Years Accounting For Three-Dimensional Earth Structure, Jorie Clark, Jay R. Alder, Marisa Borreggine, Jerry X. Mitrovica, Konstantin Latychev
Coastal Paleogeography Of The Pacific Northwest, Usa, For The Last 12,000 Years Accounting For Three-Dimensional Earth Structure, Jorie Clark, Jay R. Alder, Marisa Borreggine, Jerry X. Mitrovica, Konstantin Latychev
United States Geological Survey: Staff Publications
Predictive modeling of submerged archaeological sites requires accurate sea-level predictions in order to reconstruct coastal paleogeography and associated geographic features that may have influenced the locations of occupation sites such as rivers and embayments. Earlier reconstructions of the paleogeography of parts of the western U.S. coast used an assumption of eustatic sea level, but this neglects the large spatial variations in relative sea level (RSL) associated with glacial isostatic adjustment (GIA) and tectonics. Subsequent work using a one-dimensional (1-D) solid Earth model showed that reconstructions that accounted for GIA result in significant differences from those based on eustatic sea level. …
Guidebook For Omaha's Urban Geology And Anthropocene Nebraska Well Drillers 2022 Field Trip, Harmon Maher, Ashlee L. Dere, Melina Luethje
Guidebook For Omaha's Urban Geology And Anthropocene Nebraska Well Drillers 2022 Field Trip, Harmon Maher, Ashlee L. Dere, Melina Luethje
Geography and Geology Faculty Books and Monographs
This geologic field trip focus is somewhat atypical but arguably reflects an ongoing evolution within the geosciences. Instead of traveling out into rural settings to look at outcrops and the stratigraphy exposed, or rural landforms and their geologic history, this field trip is focused on built and engineered environments in the Omaha area and the ‘modified’ associated geologic processes such as surface and groundwater flow, weathering, and soil formation. The ongoing evolution includes an increase in a multidisciplinary system science approach and is driven by a need to address environmental and resource management challenges using new tools and conceptual frameworks. …
Provenance Of The Northern Range, Trinidad Using Detrital Zircon U-Pb Geochronology: Implications For Northern South American River System Paleogeography, Cheyenne Bartelt
Provenance Of The Northern Range, Trinidad Using Detrital Zircon U-Pb Geochronology: Implications For Northern South American River System Paleogeography, Cheyenne Bartelt
Geology: Student Scholarship & Creative Works
The Northern Range of Trinidad is located in a key area for evaluating the Mesozoic-Cenozoic evolution of the Caribbean and South American plates. Here, we present detrital zircon U-Pb geochronology for 2391 grains from ten samples collected from metasedimentary rocks of the Northern Range. These data are used to bracket the maximum depositional age of the fossil-poor metasedimentary rocks from the Northern Range and to investigate the provenance of their sedimentary protoliths. Detrital zircon ages range between 3136.5 ± 22.9 Ma and 139.0 ± 5.4 Ma, reflecting apparent contribution from a variety of crustal affinities; however, since the youngest ages …
Deciphering Regional Geology Using The New Usgs-Ewu Mineral Separation Lab, Zachary Shimp, Katlin Gamache, Travis Morton, Chad Pritchard
Deciphering Regional Geology Using The New Usgs-Ewu Mineral Separation Lab, Zachary Shimp, Katlin Gamache, Travis Morton, Chad Pritchard
2022 Symposium
U/Pb radiometric dating of zircon is one of the most widely used methods to determine the crystallization ages of igneous and metamorphic rocks and the provenance of sedimentary rocks. Eastern Washington University (EWU) has collaborated with the U.S. Geological Survey (USGS) to build a mineral separation lab for isolating zircon (and other) minerals for analysis. This lab was completed in Fall 2022 and is currently being transferred to the new ISC for future use. Graphically illustrated below are the methods used for sampling and pulverizing the rock, as well as grain mount preparation techniques. One of the EWU projects that …
Exceptional Agate Formation Found In Spokane Basalt, Matthew J. Markus
Exceptional Agate Formation Found In Spokane Basalt, Matthew J. Markus
2022 Symposium
People don’t normally associate semi-precious gems with basalt or the “boring black rock” that dominates the Eastern Washington landscape. However, a site just northeast of Cheney in the West Planes of Spokane, shows where a system of gem-filled veins can be found nestled into the 16-million-year-old (Kasbohm and Schoene, 2018) Priest Rapids Member of the Wanapum Basalt that is a part of the greater Columbia River Basalt. The volcanic rocks are the host to millimeter - 10 cm wide fractures with variable colored agate and opal.
Detrital Zircon Ages In Heavily Folded Quartzite Compared To Steptoe Butte, Travis A. Morton, Chad Pritchard
Detrital Zircon Ages In Heavily Folded Quartzite Compared To Steptoe Butte, Travis A. Morton, Chad Pritchard
2022 Symposium
Folded and altered quartzite along Interstate 90 and the Palouse to Cascades Trail out of Rosalia, WA preserves a record of the region’s tectonic past. The working hypothesis is that the sandstone is Cambrian (roughly 500 million years old) and was metamorphosed and deformed during the Sevier orogeny (roughly 150 to 50 million years ago), and then uplifted about 50 million years ago. The first step to address the hypothesis is to determine the age of the rocks using detrital zircon U/Pb analyses. The second step is for a detailed field study to identify relationships between metamorphic grades and geologic …
Species Effect On The Ecohydrology Of A Floodplain Forest In The Upper Mississippi, Claire Mchenry
Species Effect On The Ecohydrology Of A Floodplain Forest In The Upper Mississippi, Claire Mchenry
Geology Honors Projects
The primary objective of this study is to understand how soil moisture is depleted underneath native and non-native Minnesotan tree species following a rain event. It is hypothesized that soil moisture will deplete more significantly and faster underneath drought intolerant, shallow rooted species native to Minnesota. This study also focuses on utilizing remote sensing techniques to calculate the soil moisture availability across a floodplain forest using Landsat 8 images to compare satellite-derived and field-recorded soil moisture values to assess the potential of these images to remotely estimate soil moisture in floodplains.
Great Lakes Paleoclimate Review, Luke Atma, Melinda C. Higley
Great Lakes Paleoclimate Review, Luke Atma, Melinda C. Higley
Summer Research
The picture of Great Lakes Region (GLR) climate since deglaciation (about 14,000 years ago) is unclear, especially in terms of the hydroclimate (how dry, or rainy, or windy it has been). It is important to have information about past environments, and periods of past climate changes, to inform how we think about current/future climate changes, especially at regional scales. Understanding the climate of the past requires proxies for past environmental conditions, such as charcoal, pollen, or microfossils preserved in lake mud. But assessing climate change over geological time scales in the GLR is complicated by a lack of such sedimentary …
Phototrophy And Carbon Fixation In Chlorobi Postdate The Rise Of Oxygen, L. M. Ward, Patrick M. Shih
Phototrophy And Carbon Fixation In Chlorobi Postdate The Rise Of Oxygen, L. M. Ward, Patrick M. Shih
Geosciences: Faculty Publications
While most productivity on the surface of the Earth today is fueled by oxygenic photosynthesis, for much of Earth history it is thought that anoxygenic photosynthesis—using compounds like ferrous iron or sulfide as electron donors—drove most global carbon fixation. Anoxygenic photosynthesis is still performed by diverse bacteria in niche environments today. Of these, the Chlorobi (formerly green sulfur bacteria) are often interpreted as being particularly ancient and are frequently proposed to have fueled the biosphere during late Archean and early Paleoproterozoic time before the rise of oxygenic photosynthesis. Here, we perform comparative genomic, phylogenetic, and molecular clock analyses to determine …
Using Lake Sediment Chemistry In The Exploration For Nickel Laterite Deposits In Tropical Regions, Gabriela Yvonne Ramirez
Using Lake Sediment Chemistry In The Exploration For Nickel Laterite Deposits In Tropical Regions, Gabriela Yvonne Ramirez
Masters Theses
"Developing reliable geochemical indicators to guide the search for ore deposits is a long-standing goal. This particularly applies to tropical regions that are often heavily vegetated which hampers boots-on-the ground exploration efforts. Here we present the preliminary results of a study that investigates the usefulness of lake sediment chemistry in the exploration for nickel laterite ore deposits in tropical regions using Lake Izabal, Guatemala, as a case study. Lake Izabal’s catchment area contains Ni laterite deposits along its northern shore, whereas no Ni-laterite discoveries have been made in the south except for a Ni mine in the southern region that …
Lithofacies Characterization Of Marine Shelf Shale And Implicaitons On Depositional Conditions And Processes On The Continental Shelf — A Case Study Of The Upper-Cretaceous Tuscaloosa Marine Shale In Louisiana And Mississippi, U.S.A., Efren Mendez Jr
Masters Theses
"The Upper Cretaceous Tuscaloosa Marine Shale (TMS) is an unconventional shale reservoir deposited on the continental shelf of the northern Gulf of Mexico Basin. Previous studies have focused on sequence stratigraphy, thermal modeling, and well-log correlations. However, a limited understanding of the stratigraphic heterogeneity of the TMS is yet to be studied. This study aims to characterize the stratigraphic heterogeneity of the TMS using core, petrographic, and well-log analyses to better understand the depositional conditions and processes that occur on the continental shelf. The TMS has been classified into four lithofacies of very fine sands – coarse silts (LF1), medium-fine …
Surficial Geologic Map Of The Summit 7.5-Minute Quadrangle, Kentucky, Antonia E. Bottoms, Ann Hislop, Matthew Massey, Maxwell L. Hammond Iii, Michele M. Mchugh, Emily Morris
Surficial Geologic Map Of The Summit 7.5-Minute Quadrangle, Kentucky, Antonia E. Bottoms, Ann Hislop, Matthew Massey, Maxwell L. Hammond Iii, Michele M. Mchugh, Emily Morris
Contract Reports--KGS
The Summit 7.5-minute quadrangle is located south of Louisville and west of Elizabethtown along the boundary between Hardin and Grayson Counties and within the Mississippian Plateau physiographic region (McDowell, 1986). Topography is characterized by the low relief Pennyroyal region that sits at elevations between 560 to 650 ft above sea level, the low relief Mammoth Cave plateau at elevations between 750 to 900 ft, and the steep Dripping Springs escarpment that separates the two plains. Moore (1964) mapped the bedrock geology of the quadrangle, which was later digitized by Conley (2002). Mississippian bedrock is exposed throughout the quadrangle and is …
Developing And Validating A Standard Operating Procedure For Quantitative Analysis Using Central Washington University's X-Ray Diffractometer, Katherine Lucas
Developing And Validating A Standard Operating Procedure For Quantitative Analysis Using Central Washington University's X-Ray Diffractometer, Katherine Lucas
Undergraduate Honors Theses
X-ray diffraction (XRD) is widely applied in a variety of disciplines to identify crystalline solids in a powdered sample. Recent software advances have made quantitative analysis of samples easier and more accessible, but the quality of the result depends on the sample preparation and data collection procedure. This project focuses on testing methods of sample preparation and XRD data collection and analysis to lay the groundwork for refinement of the existing standard operating procedures at CWU. First, I determined the ball mill grinding time necessary to powder different mineral samples. The addition of hand grinding to ball mill-ground samples produced …
Surficial Geologic Map Of The Flaherty 7.5-Minute Quadrangle, Kentucky, Ann Hislop, Matthew Massey, Maxwell L. Hammond Iii, Antonia E. Bottoms, Michele Mchugh, Emily Morris
Surficial Geologic Map Of The Flaherty 7.5-Minute Quadrangle, Kentucky, Ann Hislop, Matthew Massey, Maxwell L. Hammond Iii, Antonia E. Bottoms, Michele Mchugh, Emily Morris
Contract Reports--KGS
The Flaherty 7.5-minute quadrangle is located southwest of Louisville and northwest of Elizabethtown along the boundary between Hardin and Meade Counties. The quadrangle includes mostly the Pennyroyal region of the Mississippian Plateau and also smaller areas of the Mammoth Cave plateau and the highly dissected Dripping Springs escarpment in the western half of the map area (McDowell, 1986). Topography is mostly characterized by pervasive sinkhole development in a lower elevation and low-relief plain, and high-relief plateaus, ridges, and knobs of the Dripping Springs escarpment scattered along the west side of the quadrangle. Swadley (1963) mapped the bedrock geology of the …
Surficial Geologic Map Of The Upton 7.5-Minute Quadrangle, Kentucky, Meredith Swallom, Matthew Massey, Maxwell L. Hammond Iii, Antonia Bottoms, Ann Hislop, Michele M. Mchugh
Surficial Geologic Map Of The Upton 7.5-Minute Quadrangle, Kentucky, Meredith Swallom, Matthew Massey, Maxwell L. Hammond Iii, Antonia Bottoms, Ann Hislop, Michele M. Mchugh
Contract Reports--KGS
The Upton 7.5-minute quadrangle is located south of Elizabethtown along the boundaries between Hardin, Hart, and Larue Counties and within the Mississippian Plateau physiographic region (McDowell, 1986). Topography is characterized by the low relief Pennyroyal plain that sits at altitudes below about 750 ft above sea level, the ridges, spurs, and isolated knobs of the intensely dissected Dripping Springs escarpment; the low relief cap of the escarpment landforms is part of the Mammoth Cave plateau region. Moore (1972) mapped the bedrock geology of the quadrangle, which was later digitized by Toth (2006). Mississippian bedrock is exposed throughout most of the …
Surficial Geologic Map Of The Millerstown 7.5-Minute Quadrangle, Kentucky, Matthew Massey, Maxwell L. Hammond Iii, Antonia Bottoms, Ann Hislop, Michele Mchugh, Emily Morris
Surficial Geologic Map Of The Millerstown 7.5-Minute Quadrangle, Kentucky, Matthew Massey, Maxwell L. Hammond Iii, Antonia Bottoms, Ann Hislop, Michele Mchugh, Emily Morris
Contract Reports--KGS
The Millerstown 7.5-minute quadrangle is located south of Louisville and southwest of Elizabethtown along the boundaries between Hardin, Grayson, and Hart Counties and within the Mississippian Plateau physiographic region (McDowell, 1986). Topography is characterized by the low relief Pennyroyal plain that sits at altitudes below about 650 ft above sea level, the low relief Mammoth Cave plateau at altitudes above about 650 ft, and steep slopes of and isolated knobs of the incised Dripping Springs escarpment that separates the two plains. Moore (1965) mapped the bedrock geology of the quadrangle, which was later digitized by Johnson (2006). Mississippian bedrock and …