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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 667 records · Page 37Linked to original sources
USGS1984

Sm-Nd, K-Ar and petrologic study of some kimberlites from eastern United States and their implication for mantle evolution

We provide new data on Sm-Nd systematics, K-Ar dating and the major element chemistry of kimberlites from the eastern United States (mostly from central New York State) and their constituent mineral phases of olivine, clinopyroxene, garnet, phlogopite and perovskite. In addition, we report Nd-isotopes in a few kimberlites from South Africa, Lesotho and from the eastern part of China. The major element compositions of the New York dike rocks and of their constituent minerals including a xenolith of eclogite are comparable with those from the Kimberley area in South Africa. The K-Ar age of emplacement of the New York dikes is further established to be 143 Ma. We have analyzed the Nd-isotopic composition of the following kimberlites and related rocks: Nine kimberlite pipes from South Africa and Lesotho, two from southern India; one from the U.S.S.R., fifteen kimberlite pipes and related dike rocks from eastern and central U.S. and two pipes from the Shandong Province of eastern China. The age of emplacement of these kimberlites ranges from 1300 million years to 90 million years. The initial Nd-isotopic compositions of these kimberlitic rocks expressed as e{open}NdIwith respect to a chondritic bulk-earth growth-curve show a range between 0 and +4, with the majority of the kimberlites being in the range 0 to +2. This range is not matched by any other suite of mantle-derived igneous rocks. This result strengthens our earlier conclusion that kimberlitic liquids are derived from a relatively primeval and unique mantle reservoir with a nearly chondritic Sm/Nd ratio. ?? 1984 Springer-Verlag.

Contributions to Mineralogy and Petrology↗
USGS2007

EAARL topography: Cape Cod National Seashore

This Web site contains 90 Lidar-derived bare earth topography maps and GIS files for the Cape Cod National Seashore. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Florida Integrated Science Center (FISC) St. Petersburg, Florida, the National Park Service (NPS), Northeast Coastal and Barrier Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to coastal resource managers.

Massachusetts↗
USGS2008

Gulf of Mexico region — Highlighting low-lying areas derived from USGS Digital Elevation Data

In support of U.S. Geological Survey (USGS) disaster preparedness efforts, this map depicts a color shaded relief representation of the area surrounding the Gulf of Mexico. The first 30 feet of relief above mean sea level are displayed as brightly colored 5-foot elevation bands, which highlight low-elevation areas at a coarse spatial resolution. Standard USGS National Elevation Dataset (NED) 1 arc-second (nominally 30-meter) digital elevation model (DEM) data are the basis for the map, which is designed to be used at a broad scale and for informational purposes only. The NED data were derived from the original 1:24,000-scale USGS topographic map bare-earth contours, which were converted into gridded quadrangle-based DEM tiles at a constant post spacing (grid cell size) of either 30 meters (data before the mid-1990s data) or 10 meters (mid-1990s and later data). These individual-quadrangle DEMs were then converted to spherical coordinates (latitude/longitude decimal degrees) and edge-matched to ensure seamlessness. Approximately one-half of the area shown on this map has DEM source data at a 30-meter resolution, with the remaining half consisting of 10-meter contour-derived DEM data or higher-resolution LIDAR data. Areas below sea level typically are surrounded by levees or some other type of flood-control structures. State and county boundary, hydrography, city, and road layers were modified from USGS National Atlas data downloaded in 2003. The NED data were downloaded in 2005.

Alabama, Florida, Louisiana, Mississippi, Texas↗
USGS2005

Calibrating a tensor magnetic gradiometer using spin data

Scalar magnetic data are often acquired to discern characteristics of geologic source materials and buried objects. It is evident that a great deal can be done with scalar data, but there are significant advantages to direct measurement of the magnetic gradient tensor in applications with nearby sources, such as unexploded ordnance (UXO). To explore these advantages, we adapted a prototype tensor magnetic gradiometer system (TMGS) and successfully implemented a data-reduction procedure. One of several critical reduction issues is the precise determination of a large group of calibration coefficients for the sensors and sensor array. To resolve these coefficients, we devised a spin calibration method, after similar methods of calibrating space-based magnetometers (Snare, 2001). The spin calibration procedure consists of three parts: (1) collecting data by slowly revolving the sensor array in the Earth?s magnetic field, (2) deriving a comprehensive set of coefficients from the spin data, and (3) applying the coefficients to the survey data. To show that the TMGS functions as a tensor gradiometer, we conducted an experimental survey that verified that the reduction procedure was effective (Bracken and Brown, in press). Therefore, because it was an integral part of the reduction, it can be concluded that the spin calibration was correctly formulated with acceptably small errors.

Scientific Investigations Report↗
USGS2013

Updating Maryland's sea-level rise projections

With its 3,100 miles of tidal shoreline and low-lying rural and urban lands, “The Free State” is one of the most vulnerable to sea-level rise. Historically, Marylanders have long had to contend with rising water levels along its Chesapeake Bay and Atlantic Ocean and coastal bay shores. Shorelines eroded and low-relief lands and islands, some previously inhabited, were inundated. Prior to the 20th century, this was largely due to the slow sinking of the land since Earth’s crust is still adjusting to the melting of large masses of ice following the last glacial period. Over the 20th century, however, the rate of rise of the average level of tidal waters with respect to land, or relative sea-level rise, has increased, at least partially as a result of global warming. Moreover, the scientific evidence is compelling that Earth’s climate will continue to warm and its oceans will rise even more rapidly. Recognizing the scientific consensus around global climate change, the contribution of human activities to it, and the vulnerability of Maryland’s people, property, public investments, and natural resources, Governor Martin O’Malley established the Maryland Commission on Climate Change on April 20, 2007. The Commission produced a Plan of Action that included a comprehensive climate change impact assessment, a greenhouse gas reduction strategy, and strategies for reducing Maryland’s vulnerability to climate change. The Plan has led to landmark legislation to reduce the state’s greenhouse gas emissions and a variety of state policies designed to reduce energy consumption and promote adaptation to climate change.

Maryl↗
USGS2026

Diverse novel and avian-associated viruses in the ileal viromes of northern mockingbird (Mimus polyglottos)

Viruses are the most abundant and diverse organisms on Earth, though only a small portion cause disease. Understanding viral diversity is key to understanding and predicting pathogen emergence and zoonotic spillover. Here, we use meta-transcriptomic sequencing to examine the viral communities in the ileum of 25 Northern Mockingbirds ( Mimus polyglottos ) from various locations across Texas. We assembled high-quality genomes of 43 viral species (40 species identified to 13 families, one to kingdom, and two to realm), 38 of which were novel. They tentatively represent avian- (n = 3), arthropod- (n = 21), plant- (n = 5) and fungi- (n = 4) associated, or other (n = 10) viruses. The arthropod-associated Dicistroviridae family was the most dominant, comprising known and potentially new species. Of potential epidemiological importance were three novel and avian-associated viruses: members of the families Hepeviridae and Picornaviridae , and a new Matryoshka RNA virus. The Matryoshka RNA virus 8 (MaRNAV-8) is sister to other Matryoshka RNA viruses, and its co-occurrence with haemosporida further supports the nested virus-parasite-vector-vertebrate host relationship of this group of viruses, with potential implications for parasite evolution, fitness and load and vector competence. The Picornaviridae virus is a member of an avian hepatovirus clade, found nested within a clade containing both the mammalian pathogens Hepatovirus A – I and the avian Tremovirus pathogens, suggestive of a newly discovered pathogen of Northern Mockingbird. Although the recovered Hepeviridae virus is of unknown pathology, its family members include the Hepatitis E viruses. With the great diversity and novelty described from ileal viromes, discriminating potential pathogens and commensal microbiota from viruses associated with food items remains challenging. A deeper understanding of virus transmission and the risk of potential zoonosis can be enhanced by tracking viruses through the food web and via inter-specific and predator-prey interactions, particular in areas subject to land-use change, where human-wildlife interactions are increased and the risks from emerging pathogens of veterinary and medical importance are more pronounced.

Texas↗
USGS2007

EAARL topography: George Washington Birthplace National Monument

This Web site contains Lidar-derived topography (first return and bare earth) maps and GIS files for George Washington Birthplace National Monument in Virginia. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, the National Park Service (NPS), Northeast Coastal and Barrier Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to coastal resource managers.

Virginia↗
USGS2007

EAARL topography: Gulf Islands National Seashore: Mississippi

This Web site contains 30 lidar-derived bare earth topography maps and GIS files for the Gulf Islands National Seashore-Mississippi. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS) Gulf Coast Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

Mississippi↗
USGS2007

EAARL Submarine Topography - Northern Florida Keys Reef Tract

This Web site contains 32 Lidar-derived bare earth topography maps and GIS files for the Northern Florida Keys Reef Tract. These lidar-derived submarine topographic maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

Florida↗
USGS2011

Lagrangian mass-flow investigations of inorganic contaminants in wastewater-impacted streams

Understanding the potential effects of increased reliance on wastewater treatment plant (WWTP) effluents to meet municipal, agricultural, and environmental flow requires an understanding of the complex chemical loading characteristics of the WWTPs and the assimilative capacity of receiving waters. Stream ecosystem effects are linked to proportions of WWTP effluent under low-flow conditions as well as the nature of the effluent chemical mixtures. This study quantifies the loading of 58 inorganic constituents (nutrients to rare earth elements) from WWTP discharges relative to upstream landscape-based sources. Stream assimilation capacity was evaluated by Lagrangian sampling, using flow velocities determined from tracer experiments to track the same parcel of water as it moved downstream. Boulder Creek, Colorado and Fourmile Creek, Iowa, representing two different geologic and hydrologic landscapes, were sampled under low-flow conditions in the summer and spring. One-half of the constituents had greater loads from the WWTP effluents than the upstream drainages, and once introduced into the streams, dilution was the predominant assimilation mechanism. Only ammonium and bismuth had significant decreases in mass load downstream from the WWTPs during all samplings. The link between hydrology and water chemistry inherent in Lagrangian sampling allows quantitative assessment of chemical fate across different landscapes.

Environmental Science & Technology↗
USGS2019

Hillslope hydrology in global change research and earth system modeling

Earth System Models (ESMs) are essential tools for understanding and predicting global change, but they cannot explicitly resolve hillslope‐scale terrain structures that fundamentally organize water, energy, and biogeochemical stores and fluxes at subgrid scales. Here we bring together hydrologists, Critical Zone scientists, and ESM developers, to explore how hillslope structures may modulate ESM grid‐level water, energy, and biogeochemical fluxes. In contrast to the one‐dimensional (1‐D), 2‐ to 3‐m deep, and free‐draining soil hydrology in most ESM land models, we hypothesize that 3‐D, lateral ridge‐to‐valley flow through shallow and deep paths and insolation contrasts between sunny and shady slopes are the top two globally quantifiable organizers of water and energy (and vegetation) within an ESM grid cell. We hypothesize that these two processes are likely to impact ESM predictions where (and when) water and/or energy are limiting. We further hypothesize that, if implemented in ESM land models, these processes will increase simulated continental water storage and residence time, buffering terrestrial ecosystems against seasonal and interannual droughts. We explore efficient ways to capture these mechanisms in ESMs and identify critical knowledge gaps preventing us from scaling up hillslope to global processes. One such gap is our extremely limited knowledge of the subsurface, where water is stored (supporting vegetation) and released to stream baseflow (supporting aquatic ecosystems). We conclude with a set of organizing hypotheses and a call for global syntheses activities and model experiments to assess the impact of hillslope hydrology on global change predictions.

Water Resources Research↗
USGS2006

Comment on “222Rn Premonitory signals for earthquakes?”

Radon and other terrestrial gases in groundwater and soil air have been studied in recent years in seismically active areas, especially in China, Japan, the former Soviet Union, and the United States, in search of changes that may be useful for earthquake prediction. Concentrations of radon, helim, hydrogen, mercury vapor, carbon dioxide, and several other gases have been found to be high along active faults. Faults may thus be paths of least resistance along which terrestrial gases generated or stored in the Earth can escape into the atmosphere. Gas-concentration changes with durations of hours to months have been observed before and after earthquakes at relatively few favorably situated sites, and their patterns have not always been repeated. Some of these sites are located as far as several hundred kilometers away from earthquake epicenters. These “sensitive” sites are generally situated along active faults, whether the seismogenic ones or not, especially at their intersections or bends, or at other structurally weak zones, possibly because of concentration of tectonic strain and abundance of pore fluids at such places (see review papers by King , 1986, 1990). Due to this selectivity and for two other important reasons, studies of terrestrial gases for earthquake prediction have not been viewed favorably by most geophysicists, especially those in the United States.

Eos Science News↗
USGS2010

Teachers guide to geologic trails in Delaware Water Gap National Recreation Area, Pennsylvania–New Jersey

T he Delaware Water Gap National Recreation Area (DEWA) contains a rich geologic and cultural history within its 68,714 acre boundary. Following the border between New Jersey and Pennsylvania, the Delaware River has cut a magnificent gorge through Kittatinny Mountain, the Delaware Water Gap, to which all other gaps in the Appalachian Mountains have been compared. Proximity to many institutions of learning in this densely populated area of the northeastern United States (Fig. 1 ) makes DEWA an ideal locality to study the geology of this part of the Appalachian Mountains. This one-day field trip comprises an overview discussion of structure, stratigraphy, geomorphology, and glacial geology within the gap. It will be highlighted by hiking a choice of several trails with geologic guides, ranging from gentle to difficult. It is hoped that the “professional” discussions at the stops, loaded with typical geologic jargon, can be translated into simple language that can be understood and assimilated by earth science students along the trails. This trip is mainly targeted for earth science educators and for Pennsylvania geologists needing to meet state-mandated education requirements for licensing professional geologists. The National Park Service, the U.S. Geological Survey, the New Jersey Geological Survey, and local schoolteachers had prepared “The Many Faces of Delaware Water Gap: A Curriculum Guide for Grades 3–6” ( Ferrence et al., 2003 ). Copies of this guide will be given to trip participants and can be downloaded from the GSA Data Repository 1 . The trip will also be useful for instruction at the graduate level. Much of the information presented in this guidebook is modified from Epstein (2006) .

New Jersey, Pennsylvania↗
USGS1976

Geologic history of Cape Cod, Massachusetts

Cape Cod, a sandy peninsula built mostly during the Ice Age, juts into the Atlantic Ocean like a crooked arm. Because of its exposed location, Cape Cod was visited by many early explorers. Although clear-cut evidence is lacking, the Vikings may have sighted this land about 1,000 years ago. It was visited by Samuel de Champlain in 1605, and his detailed descriptions and charts have helped present-day scientists to determine the rate of growth of Nauset Beach marsh and Nauset spit. Bartholomew Gosnold, a lesser known explorer, settled for a short time on the Elizabeth Islands to the southwest and gave Cape Cod its name in 1602. The Pilgrims first landed in America on the tip of Lower Cape Cod after they were turned back from their more southerly destination by shoals between Cape Cod and Nantucket Island. On Cape Cod they found potable water and food and had their first fight with the natives. The Pilgrims, however, decided that this land was too isolated, too exposed, and too sandy to support them, and they sailed across Cape Cod Bay to establish Plymouth. These features remain today. Small villages are separated by large areas of forest, dune, beach, and marsh. This unspoiled natural beauty makes Cape Cod one of the most favored vacation areas for the people living in the thickly settled Northeastern States. Cape Cod is of particular interest to geologists because it was formed by glaciers very recently in terms of geologic time. During the Great Ice Age, (the Pleistocene Epoch which began 2 to 3 million years ago), glaciers advanced from the north into the temperate regions of the Earth. Glacial ice covered the land at least four times. Each advance was accompanied by a worldwide lowering of sea level because the source of the ice was water from the seas. When the glaciers melted, the climate and sea level were probably much like they are today. In fact, some scientists believe that the Earth is presently between glacial episodes and that ice once again will advance across the land.

Massachusetts↗
USGS2007

EAARL topography: Gulf Islands National Seashore: Florida

This Web site contains 33 lidar-derived bare earth topography maps and GIS files for the Gulf Islands National Seashore-Florida. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS), Gulf Coast Network, Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

Florida↗
USGS2008

Living in Yellowstone's Caldera: A geochemical trophic cascade in elk

Though the geology of earth's rare geothermal environments and their associated microbial communities are intensely studied, less scientific attention has focused on their potential effects through the plant-herbivore-carnivore trophic chain. The west-central portion of Yellowstone National Park contains a 2000-km 2 volcanic caldera with 2- to 60-million-year-old, predominantly rhyolitic, rocks that produce relatively infertile soils. The caldera area contains one of the largest concentrations of active geothermal features in the world, including thousands of geysers, fumaroles , hot springs, and mud pots. In many other chapters of this book, we address the ecological impacts of this unique geology to the ecology of the large mammals that live within the caldera, primarily through the effects of geothermal heat on snow pack. In this chapter, we explore the unique geochemistry of the geothermal environments and the consequences of this geochemistry to elk and perhaps other herbivores that reside within the caldera. These studies were prompted by behavioral and demographic observations of elk during the initial years of our studies that we could not explain and, in turn, led us to formulate hypotheses about potential geochemical influences on elk ecology. Specifically, we contrast the concentrations of fluoride (F) and silica (SiO 2 ) found in the Madison headwaters area with areas on Yellowstone's northern range located approximately 50 km to the northwest, where geothermal features are rare or absent. We then trace the consequences of geochemical differences through abiotic and biotic linkages in the ecosystem.

Book↗
USGS2011

Toward a consistent model for strain accrual and release for the New Madrid Seismic Zone, central United States

At the heart of the conundrum of seismogenesis in the New Madrid Seismic Zone is the apparently substantial discrepancy between low strain rate and high recent seismic moment release. In this study we revisit the magnitudes of the four principal 1811–1812 earthquakes using intensity values determined from individual assessments from four experts. Using these values and the grid search method of Bakun and Wentworth (1997), we estimate magnitudes around 7.0 for all four events, values that are significantly lower than previously published magnitude estimates based on macroseismic intensities. We further show that the strain rate predicted from postglacial rebound is sufficient to produce a sequence with the moment release of one M max 6.8 every 500 years, a rate that is much lower than previous estimates of late Holocene moment release. However, M w 6.8 is at the low end of the uncertainty range inferred from analysis of intensities for the largest 1811–1812 event. We show that M w 6.8 is also a reasonable value for the largest main shock given a plausible rupture scenario. One can also construct a range of consistent models that permit a somewhat higher M max , with a longer average recurrence rate. It is thus possible to reconcile predicted strain and seismic moment release rates with alternative models: one in which 1811–1812 sequences occur every 500 years, with the largest events being M max ∼6.8, or one in which sequences occur, on average, less frequently, with Mmax of ∼7.0. Both models predict that the late Holocene rate of activity will continue for the next few to 10 thousand years.

New Madrid Seismic Zone↗
USGS2019

Introduction to special issue on gas hydrate in porous media: Linking laboratory and field‐scale phenomena

The proliferation of drilling expeditions focused on characterizing natural gas hydrate as a potential energy resource has spawned widespread interest in gas hydrate reservoir properties and associated porous media phenomena. Between 2017 and 2019, a Special Section of this journal compiled contributed papers elucidating interactions between gas hydrate and sediment based on laboratory, numerical modeling, and field studies. Motivated mostly by field observations in the northern Gulf of Mexico and offshore Japan, several papers focus on the mechanisms for gas hydrate formation and accumulation, particularly with vapor phase gas, not dissolved gas, as the precursor to hydrate. These studies rely on numerical modeling or laboratory experiments using sediment packs or benchtop micromodels. A second focus of the Special Section is the role of fines in inhibiting production of gas from methane hydrate, controlling the distribution of hydrate at a pore scale, and influencing the bulk behavior of seafloor sediments. Other papers fill knowledge gaps related to the physical properties of hydrate-bearing sediments and advance new approaches in coupled thermal-mechanical modeling of these sediments during hydrate dissociation. Finally, one study addresses the long-standing question about the fate of methane hydrate at the molecular level when CO2 is injected into natural reservoirs under hydrate-forming conditions.

Journal of Geophysical Research B: Solid Earth↗