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At least 1,225 records · Page 68Linked to original sources
USGS2005

Surface gamma-ray survey of the Barre West quadrangle, Washington and Orange Counties, Vermont

This study was designed to determine the levels of naturally occurring radioactivity in bedrock from surface measurements at outcrops during the course of 1:24,000-scale geologic mapping and to determine which rock types were potential sources of radionuclides. Elevated levels of total alpha particle radiation (gross alpha) occur in a public water system in Montpelier, Vermont. Measured gross alpha levels in the Murray Hill water system (Vermont Dept. of Environmental Conservation, unpub. data, 2005) have exceeded the maximum contaminant level of 15 picocuries per liter (pCi/l) set by the Environmental Protection Agency (EPA) (EPA, 2000). The Murray Hill system began treatment for radium in 1999. Although this treatment was successful, annual monitoring for gross alpha, radium, and uranium continues as required (Jon Kim, written communication, 2005). The water system utilizes a drilled bedrock well located in the Silurian-Devonian Waits River Formation. Kim (2002) summarized radioactivity data for Vermont, and aside from a statewide assessment of radon in public water systems (Manning and Ladue, 1986) and a single flight line from the National Uranium Resource Evaluation (NURE) (Texas Instruments, 1976) (fig. 1), no data are available to identify the potential sources of naturally occurring radioactivity in the local bedrock. Airborne gamma-ray surveys are typically used for large areas (Duval, 2001, 2002), and ground-based surveys are more commonly used for local site assessments. For example, ground-based surveys have been used for fault mapping (Iwata and others, 2001), soil mapping (Roberts and others, 2003), environmental assessments (Stromswold and Arthur, 1996), and mineral exploration (Jubeli and others, 1998). Duval (1980) summarized the methods and applications of gamma- ray spectrometry. In this study, we present the results from a ground-based gamma-ray survey of bedrock outcrops in the 7.5-minute Barre West quadrangle, Vermont. Other related and ongoing studies in the area are addressing potential mineral sources of radionuclides (Satkoski and Walsh, 2004; Satkoski and others, 2005), radionuclides in ground water (Kim and others, 2005), and bedrock geology.

Scientific Investigations Report↗
USGS1995

Quaternary Geologic Map of the Lake of the Woods 4 Degrees x 6 Degrees Quadrangle, United States and Canada

The Quaternary Geologic Map of the Lake of the Woods 4 deg x 6 deg Quadrangle, United States and Canada, was mapped as part of the U.S. Geological Survey Quaternary Geologic Atlas of the United States map series (Miscellaneous Investigations Series I-1420, NM-15). The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. This map is a product of collaboration of the Ontario Geological Survey, the Minnesota Geological Survey, the Manitoba Department of Energy and Mines, and the U.S. Geological Survey, and is designed for both scientific and practical purposes. It was prepared in two stages. First, separate maps and map explanations were prepared by the compilers. Second, the maps were combined, integrated, and supplemented by the editor. Map unit symbols were revised to a uniform system of classification and the map unit descriptions were prepared by the editor from information received from the compilers and from additional sources listed under Sources of Information. Diagrams accompanying the map were prepared by the editor. For scientific purposes, the map differentiates Quaternary surficial deposits on the basis of lithology or composition, texture or particle size, structure, genesis, stratigraphic relationships, engineering geologic properties, and relative age, as shown on the correlation diagram and indicated in the description of map units. Deposits of some constructional landforms, such as kame moraine deposits, are distinguished as map units. Deposits of erosional landforms, such as outwash terraces, are not distinguished, although glaciofluvial, ice-contact, and lacustrine deposits that are mapped may be terraced. As a Quaternary geologic map, it serves as a base from which a variety of maps relating Quaternary geologic history can be derived. For practical purposes, the map is a surficial materials map. Materials are distinguished on the basis of lithology or composition, texture or particle size, and other physical, chemical, and engineering characteristics. It is not a map of soils that are recognized and classified in pedology or agronomy. Rather, it is a generalized map of soils as recognized in engineering geology, or of substrata or parent materials in which pedologic or agronomic soils are formed. As a materials map, it serves as a base from which a variety of maps for use in planning engineering, land-use, or land-management projects can be derived.

IMAP↗
USGS2015

Peak flow regression equations For small, ungaged streams in Maine: Comparing map-based to field-based variables

Regression equations to estimate peak streamflows with 1- to 500-year recurrence intervals (annual exceedance probabilities from 99 to 0.2 percent, respectively) were developed for small, ungaged streams in Maine. Equations presented here are the best available equations for estimating peak flows at ungaged basins in Maine with drainage areas from 0.3 to 12 square miles (mi 2 ). Previously developed equations continue to be the best available equations for estimating peak flows for basin areas greater than 12 mi 2 . New equations presented here are based on streamflow records at 40 U.S. Geological Survey streamgages with a minimum of 10 years of recorded peak flows between 1963 and 2012. Ordinary least-squares regression techniques were used to determine the best explanatory variables for the regression equations. Traditional map-based explanatory variables were compared to variables requiring field measurements. Two field-based variables—culvert rust lines and bankfull channel widths—either were not commonly found or did not explain enough of the variability in the peak flows to warrant inclusion in the equations. The best explanatory variables were drainage area and percent basin wetlands; values for these variables were determined with a geographic information system. Generalized least-squares regression was used with these two variables to determine the equation coefficients and estimates of accuracy for the final equations.

Maine↗
USGS2013

Groundwater conditions in Georgia, 2010–2011

The U.S. Geological Survey collects groundwater data and conducts studies to monitor hydrologic conditions, better define groundwater resources, and address problems related to water supply, water use, and water quality. In Georgia, water levels were monitored continuously at 186 wells during calendar year 2010 and at 181 wells during calendar year 2011. Because of missing data or short periods of record (less than 3 years) for several of these wells, a total of 168 wells are discussed in this report. These wells include 17 in the surficial aquifer system, 19 in the Brunswick aquifer system and equivalent sediments, 70 in the Upper Floridan aquifer, 16 in the Lower Floridan aquifer and underlying units, 10 in the Claiborne aquifer, 1 in the Gordon aquifer, 11 in the Clayton aquifer, 14 in the Cretaceous aquifer system, 2 in Paleozoic-rock aquifers, and 8 in crystalline-rock aquifers. Data from the well network indicate that water levels generally declined during the 2010 through 2011 calendar-year period, with water levels declining in 158 wells and rising in 10. Water levels declined over the period of record at 106 wells, increased at 56 wells, and remained relatively constant at 6 wells. In addition to continuous water-level data, periodic water-level measurements were collected and used to construct potentiometric-surface maps for the Upper Floridan aquifer in Camden, Charlton, and Ware Counties, Georgia, and adjacent counties in Florida during May–June 2010, and in the following areas in Georgia: the Brunswick area during August 2010 and August 2011, in the Albany–Dougherty County area during November 2010 and November 2011, and in the Augusta–Richmond County area during October 2010 and August 2011. In general, water levels in these areas were lower during 2011 than during 2010; however, the configuration of the potentiometric surfaces in each of the areas showed little change. Groundwater quality in the Floridan aquifer system is monitored in the Albany, Savannah, and Brunswick areas of Georgia. In the Albany area, nitrate as nitrogen concentrations in the Upper Floridan aquifer during 2011 generally decreased from 2010; however, concentrations in two wells remained above the U.S. Environmental Protection Agency (USEPA) 10-milligrams-per-liter (mg/L) drinking-water standard. In the Savannah area, specific conductance and chloride concentrations were measured in water samples from discrete depths in two wells completed in the Upper Floridan aquifer. Data from the two wells indicate that chloride concentrations in the Upper Floridan aquifer showed little change during calendar years 2010 through 2011 and remained below the 250 mg/L USEPA secondary drinking-water standard. During calendar years 2010 through 2011, chloride concentrations in the Lower Floridan aquifer increased slightly at Tybee Island and Skidaway Island, remaining above the drinking-water standard. In the Brunswick area, maps showing the chloride concentration of water in the Upper Floridan aquifer constructed using data collected from 32 wells during August 2010 and from 30 wells during August 2011 indicate that chloride concentrations remained above the USEPA secondary drinking-water standard in an approximately 2-square-mile area. During calendar years 2010 through 2011, chloride concentrations generally decreased in over 70 percent of the wells sampled during 2011, with a maximum decrease of 200 mg/L in a well located in the north-central part of the Brunswick area.

Georgia↗
USGS2016

Groundwater conditions in Georgia, 2012–14

The U.S. Geological Survey collects groundwater data and conducts studies to monitor hydrologic conditions, better define groundwater resources, and address problems related to water supply, water use, and water quality. In Georgia, water levels were monitored continuously at 181 wells during calendar year 2012, 185 wells during calendar year 2013, and at 171 wells during calendar year 2014. Because of missing data or short periods of record (less than 3 years) for several of these wells, a total of 164 wells are discussed in this report. These wells include 17 in the surficial aquifer system, 18 in the Brunswick aquifer system and equivalent sediments, 68 in the Upper Floridan aquifer, 15 in the Lower Floridan aquifer and underlying units, 10 in the Claiborne aquifer, 1 in the Gordon aquifer, 11 in the Clayton aquifer, 16 in the Cretaceous aquifer system, 2 in Paleozoic-rock aquifers, and 6 in crystalline-rock aquifers. Data from the well network indicate that water levels generally rose during the 2012 through 2014 calendar-year period, with water levels rising in 151 wells, declining in 12, and remained about the same in 1. Water levels declined over the long-term period of record at 94 wells, increased at 60 wells, and remained relatively constant at 10 wells. In addition to continuous water-level data, periodic water-level measurements were collected and used to construct potentiometric-surface maps for the Upper Floridan aquifer in the following areas in Georgia: the Brunswick-Glynn County area during August 2012 and October 2014 and in the Albany-Dougherty County area during November 2012 and November 2014. Periodic water-level measurements were also collected and used to construct potentiometric surface maps for the Cretaceous aquifer system in the Augusta-Richmond County area during August 2012 and July 2014. In general, water levels in these areas were higher during 2014 than during 2012; however, the configuration of the potetiometric surface in each of the areas showed little change. In the Brunswick area, maps showing chloride concentration of water in the Upper Floridan aquifer (constructed using data collected from 25 wells during August 2012 and from 32 wells during October 2014) indicate that chloride concentrations remained above the U.S. Environmental Protection Agency's secondary drinking-water standard in an approximately 2-square-mile area. During calendar years 2012 through 2014, chloride concentrations generally increased in over 90 percent of the wells sampled with a maximum increase of 410 milligrams per liter in a well located in the north-central part of the Brunswick area.

Georgia↗
USGS1987

Normal faulting of the Daiichi-Kashima Seamount in the Japan Trench revealed by the Kaiko I cruise, Leg 3

A detailed topographic and geophysical survey of the Daiichi-Kashima Seamount area in the southern Japan Trench, northwestern Pacific margin, clearly defines a high-angle normal fault which splits the seamount into two halves. A fan-shaped zone was investigated along 2–4 km spaced, 100 km long subparallel tracks using narrow multi-beam (Seabeam) echo-sounder with simultaneous measurements of gravity, magnetic total field and single-channel seismic reflection records. Vertical displacement of the inboard half was clearly mapped and its normal fault origin was supported. The northern and southern extensions of the normal fault beyond the flank of the seamount were delineated. Materials on the landward trench slope are displaced upward and to sideways away from the colliding seamount. Canyons observed in the upper landward slope terminate at the mid-slope terrace which has been uplifted since start of subduction of the seamount. Most of the landward slope except for the landward walls aside the seamount comprises only a landslide topography in a manner similar to the northern Japan Trench wall. This survey was conducted on R/V “Jean Charcot” as a part of the Kaiko I cruise, Leg 3, in July–August 1984 under the auspices of the French-Japanese scientific cooperative program.

Earth and Planetary Science Letters↗
USGS2015

Geologic field-trip guide to Lassen Volcanic National Park and vicinity, California

This geologic field-trip guide provides an overview of Quaternary volcanism in and around Lassen Volcanic National Park in northern California. The guide begins with a comprehensive overview of the geologic framework and the stratigraphic terminology of the Lassen region, based primarily on the “Geologic map of Lassen Volcanic National Park and vicinity” (Clynne and Muffler, 2010). The geologic overview is then followed by detailed road logs describing the volcanic features that can readily be seen in the park and its periphery. Twenty-one designated stops provide detailed explanations of important volcanic features. The guide also includes mileage logs along the highways leading into the park from the major nearby communities. The field-trip guide is intended to be a flexible document that can be adapted to the needs of a visitor approaching the park from any direction.

California↗
USGS2023

Prediction of the probability of elevated nitrate concentrations at groundwater depths used for drinking-water supply in the Puget Sound basin, Washington, 2004–19

The Puget Sound basin encompasses the 13,700-square-mile area that drains to the Puget Sound and the adjacent marine waters of Washington State. Well more than 4 million people live within the basin, with numbers continuing to increase, who rely on the basin’s natural resources including groundwater. The Puget Sound Partnership was created by a Washington State statute to implement a science-based recovery of the Puget Sound to help address impacts to these resources. As part of the recovery, the partnership developed the Puget Sound Vital Signs as measures of ecosystem health that guide the assessment of progress toward Puget Sound recovery goals. The Puget Sound Partnership Leadership Council adopted a Drinking Water Vital Sign associated with human health and quality of life, recognizing certain indicators as integral to the sustainability of Puget Sound recovery efforts. One such Vital Sign indicator was the vulnerability of groundwater throughout the aquifers of the Puget Sound basin to elevated nitrate concentrations as defined by the probability of exceeding 2 milligrams/liter (mg/L) at a specific location and well depth. The U.S. Geological Survey (USGS) led the effort to characterize groundwater vulnerability. For this study, groundwater vulnerability refers to a probability with which a contaminant applied at or near the land surface can migrate to the aquifer of interest for a given set of land-use practices. Nitrate concentration data were selected for evaluation because elevated nitrate concentrations are typically caused by anthropogenic activities and have been associated with deleterious impacts on human health. To identify groundwater vulnerability to elevated nitrate concentrations, logistic regression was used to relate anthropogenic (human associated) and natural variables to the occurrence of elevated nitrate concentrations in untreated groundwater from large public water supply system wells found within the Washington State Department of Health Sentry database. Variables that were analyzed included well depth, soil hydraulic conductivity, precipitation, population density, fertilizer application amounts, and land-use types. Statistically significant models that predicted the probabilities of groundwater nitrate concentrations greater than 2 mg/L based on the predictor variables were created for the time periods 2000–04, 2005–09, 2010–14, and 2015–19. For all time periods, well depth and a measure of the abundance of urban and agricultural land over or near the well consistently helped explain the vulnerability of the well to elevated nitrate concentrations defined as a probability of exceeding 2 mg/L of nitrate. Precipitation and (or) soil hydraulic conductivity were also important predictor variables in the models. The models for each time period were used to create maps of groundwater vulnerability at 150- and 300-foot depths throughout the Puget Sound basin. As expected, the most vulnerable locations were associated with shallower well depths and increased agriculture and urban land cover. Across all four time periods, groundwater vulnerability throughout the Puget Sound was low, with probabilities of exceeding 2 mg/L concentrations of nitrate at depths at 150 and 300 feet typically less than 50 percent. Results also found a slight decrease in probabilities of elevated nitrate concentrations throughout the basin over time. More specifically, additional statistical tests found that groundwater with probabilities of less than about 60 percent declined from 2000 to 2019 and represented more than 75 percent of the modeled Puget Sound basin aquifer. Wells with greater than 60 percent probability increased over the same time period but represented only about 25 percent of the aquifer. The maps and statistical analysis presented in the study provide valuable and informative evaluation of the vulnerability of groundwater in the Puget Sound basin to elevated nitrate concentrations. The probability maps do not represent measured nitrate concentrations in groundwater, but rather they present the probability that nitrate concentrations exceed 2 mg/L. The models and predictions from this study are a viable indicator for the Puget Sound Partnership’s Healthy Human Population—Drinking Water Vital Sign. The logistic regression modeling approach presented here benefits water managers by allowing them to assess temporal trends in a range of probabilities, explore vulnerability changes as new regional land cover and anthropogenic data are generated, and distinguish vulnerabilities at different depths within the aquifer.

Washington↗
USGS2007

Mapping known and potential mineral occurrences and host rocks in the Bonnifield Mining District using minimal cloud- and snow-cover ASTER data

On July 8, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor acquired satellite imagery of a 60-kilometer-wide swath covering a portion of the Bonnifield mining district within the southernmost part of the Tintina Gold Province, Alaska, under unusually favorable conditions of minimal cloud and snow cover. Although rocks from more than eight different lithotectonic terranes are exposed within the extended swath of data, we focus on volcanogenic massive sulfides (VMS) and porphyry deposits within the Yukon-Tanana terrane (YTT), the largest Mesozoic accretionary terrane exposed between the Denali fault system to the south of Fairbanks and the Tintina fault system to the north of Fairbanks. Comparison of thermal-infrared region (TIR) decorrelation stretch data to available geologic maps indicates that rocks from the YTT contain a wide range of rock types ranging in composition from mafic metavolcanic rocks to felsic rock types such as metarhyolites, pelitic schists, and quartzites. The nine-band ASTER visible-near-infrared region--short-wave infrared region (VNIR-SWIR) reflectance data and spectral matched-filter processing were used to map hydrothermal alteration patterns associated with VMS and porphyry deposit types. In particular, smectite, kaolinite, opaline silica, jarosite and (or) other ferric iron minerals defined narrow (less than 250-meter diameter) zonal patterns around Red Mountain and other potential VMS targets. Using ASTER we identified some of the known mineral deposits in the region, as well as mineralogically similar targets that may represent potential undiscovered deposits. Some known deposits were not identified and may have been obscured by vegetation or snow cover or were too small to be resolved.

Alaska, Yukon↗
USGS2009

Ground-Water Conditions and Studies in Georgia, 2006-2007

The U.S. Geological Survey collects ground-water data and conducts studies to monitor hydrologic conditions, better define ground-water resources, and address problems related to water supply, water use, and water quality. Water levels were monitored continuously, in Georgia, in a network of 184 wells during 2006 and 182 wells during 2007. Because of missing data or the short period of record (less than 3 years) for several of these wells, a total of 166 wells from the network are discussed in this report. These wells include 18 in the surficial aquifer system, 21 in the Brunswick aquifer system and equivalent sediments, 67 in the Upper Floridan aquifer, 15 in the Lower Floridan aquifer and underlying units, 10 in the Claiborne aquifer, 1 in the Gordon aquifer, 11 in the Clayton aquifer, 12 in the Cretaceous aquifer system, 2 in Paleozoic-rock aquifers, and 9 in crystalline-rock aquifers. Data from the network indicate that water levels generally declined from 2005 levels, with water levels in 99 wells below normal, 52 wells in the normal range, 12 wells above normal, and 3 wells with insufficient data for comparison of 5-year trends and period of record statistics. In addition to continuous water-level data, periodic synoptic water-level measurements were collected and used to construct potentiometric-surface maps for the Upper Floridan aquifer in Camden, Charlton, and Ware Counties, Georgia, and adjacent counties in Florida during September 2006 and 2007, in the Brunswick area during July 2006 and August 2007, and in the City of Albany-Dougherty County area during October 2006 and October 2007. In general, the configuration of the potentiometric surfaces showed little change during 2006-2007 in each of the areas. Ground-water quality in the Upper Floridan aquifer is monitored in the Albany, Savannah, and Brunswick areas and in Camden County; and water quality in the Lower Floridan aquifer is monitored in the Savannah and Brunswick areas and in Camden County. In the Albany area, nitrate concentrations generally have increased since the end of the drought during 2002. During 2006, water from two wells had nitrate as N concentrations above the U.S. Environmental Protection Agency's (USEPA) 10-milligram-per-liter (mg/L) drinking-water standard. During 2007, only one well had concentrations above the drinking-water standard. In the Savannah area, measurement of fluid conductivity and chloride concentration in water samples from discrete depths in three wells completed in the Upper Floridan aquifer and one well in the Lower Floridan aquifer were used to assess changes in water quality in the Savannah area. At Tybee Island, chloride concentrations in samples from the Lower Floridan aquifer decreased during 2006-2007 but were still above the 250-mg/L USEPA drinking-water standard. At Skidaway Island, water in the Upper Floridan aquifer is fresh, and chloride concentrations did not appreciably change during 2006-2007. However, chloride concentrations in samples collected from the Lower Floridan aquifer during 2006-2007 showed disparate changes; whereby, chloride concentration increased in the shallowest sampled interval (900 feet) and decreased slightly in a deeper sampled interval (1,070 feet). At Fort Pulaski, water samples collected from the Upper Floridan aquifer were fresh and did not appreciably changeduring 2006-2007. In the Brunswick area, maps showing the chloride concentration of water in the Upper Floridan aquifer were constructed by using data collected from 29 wells during July 2006 and from 26 wells during August 2007. Analyses indicate that concentrations remained above the USEPA drinking-water standard in an approximate 2-square-mile area. During 2006-2007, chloride concentrations increased in only three of the wells sampled and ranged from 4.0 to 20 mg/L chloride. In the Camden County area, chloride concentration during 2006-2007 was analyzed in water samples collected from eight wells, six completed i

Georgia↗
USGS2015

Porphyry copper assessment of the Central Asian Orogenic Belt and eastern Tethysides: China, Mongolia, Russia, Pakistan, Kazakhstan, Tajikistan, and India: Chapter X in Global mineral resource assessment

The U.S. Geological Survey collaborated with international colleagues to assess undiscovered resources in porphyry copper deposits in the Central Asian Orogenic Belt and eastern Tethysides. These areas host 20 known porphyry copper deposits, including the world class Oyu Tolgoi deposit in Mongolia that was discovered in the late 1990s. The study area covers major parts of the world’s largest orogenic systems. The Central Asian Orogenic Belt is a collage of amalgamated Precambrian through Mesozoic terranes that extends from the Ural Mountains in the west nearly to the Pacific Coast of Asia in the east and records the evolution and final closure of the Paleo-Asian Ocean in Permian time. The eastern Tethysides, the orogenic belt to the south of the Central Asian Orogenic Belt, records the evolution of another ancient ocean system, the Tethys Ocean. The evolution of these orogenic belts involved magmatism associated with a variety of geologic settings appropriate for formation of porphyry copper deposits, including subduction-related island arcs, continental arcs, and collisional and postconvergent settings. The original settings are difficult to trace because the arcs have been complexly deformed and dismembered by younger tectonic events. Twelve mineral resource assessment tracts were delineated to be permissive for the occurrence of porphyry copper deposits based on mapped and inferred subsurface distributions of igneous rocks of specific age ranges and compositions. These include (1) nine Paleozoic tracts in the Central Asian Orogenic Belt, which range in area from about 60,000 to 800,000 square kilometers (km 2 ); (2) a complex area of about 400,000 km 2 on the northern margin of the Tethysides, the Qinling-Dabie tract, which spans central China and areas to the west, encompassing Paleozoic through Triassic igneous rocks that formed in diverse settings; and (3) assemblages of late Paleozoic and Mesozoic rocks that define two other tracts in the Tethysides, the 100,000 km 2 Jinsajiang tract and the 300,000 km 2 Tethyan-Gangdese tract. Assessment participants evaluated applicable grade and tonnage models and estimated numbers of undiscovered deposits at different confidence levels for each permissive tract. The estimates were then combined with the selected grade and tonnage models using Monte Carlo simulations to generate probabilistic estimates of undiscovered resources. Additional resources in extensions of deposits with identified resources were not specifically evaluated. Assessment results, presented in tables and graphs, show amounts of metal and rock in undiscovered deposits at selected quantile levels of probability (0.95, 0.9, 0.5, 0.1, and 0.05 confidence levels), as well as the arithmetic mean and associated standard deviations and variances for each tract. This assessment estimated a total of 97 undiscovered porphyry copper deposits within the assessed permissive tracts. This represents nearly five times the 20 known deposits. Predicted mean resources that could be associated with these undiscovered deposits are about 370,000,000 metric tons (t) of copper, 10,000 t of gold, 7,700,000 t of molybdenum, and 120,000 t of silver. The assessment area is estimated to contain about five times as much copper in undiscovered deposits as has been identified to date. This report includes a summary of the data used in the assessment, a brief overview of the geologic framework of the area, descriptions of permissive tracts and known deposits, maps, and tables. A geographic information system database that accompanies this report includes the tract boundaries and known porphyry copper deposits, significant prospects, and prospects. Assessments of overlapping younger rocks and adjacent areas are included in separate reports available on-line at http://minerals.usgs.gov/global/ .

Scientific Investigations Report↗
USGS2020

Biological and habitat assessment of the Lower Rouge River, Michigan 2018

A key component of evaluating the success of habitat remediation projects is determining preremediation conditions, biotic and abiotic, to establish a baseline and compare with postproject conditions. The Rouge River, Michigan, is a Great Lakes Area of Concern with a listed Beneficial Use Impairment related to loss of fish and wildlife habitat. A biological and habitat assessment was completed in the lower Rouge River, focused along a nearly 7-kilometer stretch of river that includes a concrete channel anticipated to be removed by 2022, to determine prerestoration conditions. Surveys documented the presence and quality of physical habitat, presence of herpetofauna, and quantified macroinvertebrate and fish assemblages at 12 sites (3 upstream from the concrete channel, 6 within the concrete channel, and 3 downstream from the concrete channel). Macroinvertebrate assemblages were dominated by Chironomidae and Oligochaeta for June and September. The electrofishing catch per unit effort was driven by Notropis atherinoides (emerald shiner) catches in June and emerald shiner and Dorosoma cepedianum (gizzard shad) catches in September. Graptemys geographica (northern map turtle) was the most common reptile observed throughout the lower Rouge River. No submergent macrophytes were discovered, and riparian vegetation was sparse in the concrete channel section. No sites scored “excellent” (total score greater than 154), upstream control sites scored “good” for overall qualitative habitat assessments (total score 105–154), and all concrete channel and downstream control sites were ranked as “marginal” (total score 56–104) or “poor” habitat (total score 0–55). Results from this assessment can be used to compare with postremediation projects in the lower Rouge River.

Michigan↗
USGS2021

Recovery and analysis of ancient beetle DNA from subfossil packrat middens using high-throughput sequencing

The study of ancient DNA is revolutionizing our understanding of paleo-ecology and the evolutionary history of species. Insects are essential components in many ecosystems and constitute the most diverse group of animals. Yet they are largely neglected in ancient DNA studies. We report the results of the first targeted investigation of insect ancient DNA to positively identify subfossil insects to species, which includes the recovery of endogenous content from samples as old as ~ 34,355 ybp. Potential inhibitors currently limiting widespread research on insect ancient DNA are discussed, including the lack of closely related genomic reference sequences (decreased mapping efficiency) and the need for more extensive collaborations with insect taxonomists. The advantages of insect-based studies are also highlighted, especially in the context of understanding past climate change. In this regard, insect remains from ancient packrat middens are a rich and largely uninvestigated resource for exploring paleo-ecology and species dynamics over time.

Scientific Reports↗
USGS2010

A method for assessing carbon stocks, carbon sequestration, and greenhouse-gas fluxes in ecosystems of the United States under present conditions and future scenarios

he Energy Independence and Security Act of 2007 (EISA), Section 712, mandates the U.S. Department of the Interior to develop a methodology and conduct an assessment of the Nation’s ecosystems, focusing on carbon stocks, carbon sequestration, and emissions of three greenhouse gases (GHGs): carbon dioxide, methane, and nitrous oxide. The major requirements include (1) an assessment of all ecosystems (terrestrial systems, such as forests, croplands, wetlands, grasslands/shrublands; and aquatic ecosystems, such as rivers, lakes, and estuaries); (2) an estimate of the annual potential capacities of ecosystems to increase carbon sequestration and reduce net GHG emissions in the context of mitigation strategies (including management and restoration activities); and (3) an evaluation of the effects of controlling processes, such as climate change, land-use and land-cover change, and disturbances such as wildfires. The concepts of ecosystems, carbon pools, and GHG fluxes follow conventional definitions in use by major national and international assessment or inventory efforts. In order to estimate current ecosystem carbon stocks and GHG fluxes and to understand the potential capacity and effects of mitigation strategies, the method will use two time periods for the assessment: 2001 through 2010, which establishes a current ecosystem carbon and GHG baseline and will be used to validate the models; and 2011 through 2050, which will be used to assess potential capacities based on a set of scenarios. The scenario framework will be constructed using storylines of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES), along with both reference and enhanced land-use and land-cover (LULC) and land-management parameters. Additional LULC and land-management mitigation scenarios will be constructed for each storyline to increase carbon sequestration and reduce GHG fluxes in ecosystems. Input from regional experts and stakeholders will be solicited to construct these scenarios. The methods for mapping the current LULC and ecosystem disturbances will require the extensive use of both remote-sensing data and field-survey data (for example, forest inventories) to capture and characterize landscape-changing events. For potential LULC changes and ecosystem disturbances, key drivers such as socioeconomic and climate changes will be used in addition to the biophysical data. The result of these analyses will be a series of maps for each future year for each scenario. These annual maps will form the basis for estimating carbon storage and GHG emissions. For terrestrial ecosystems, carbon storage, carbon-sequestration capacities, and GHG emissions under the present conditions and future scenarios will be assessed using the LULC-change and ecosystem-disturbance estimates in map format with a spatially explicit biogeochemical ensemble modeling system that incorporates properties of management activities (such as tillage or harvesting) and properties of individual ecosystems (such as energy exchange, vegetation characteristics, hydrological cycling, and soil attributes). For aquatic ecosystems, carbon burial in sediments and fluxes of GHG are functions of the present and future potential stream flow and sediment transport and will be assessed using empirical hydrological modeling methods. Validation and uncertainty analysis methods described in the methodology will follow established guidelines to assess the quality of the assessment results. The U.S. Environmental Protection Agency’s Level II ecoregions map will be the practical instrument for developing and delivering assessment results. Consequently, the ecoregion (there are 22 modified ecoregions) will be the reporting unit of the assessment because the scenarios, assessment results, validation, and uncertainty analysis will be produced at that scale. The implementation of these methods will require collaborations among various Federal agencies, State agencies, nongovernmental organizations, and the science community. Using the method described in this document, the assessment can be completed in approximately 3 to 4 years. The primary deliverables will be assessment reports containing tables, charts, and maps that will present the estimated GHG parameters annually for 2001 through 2050 by ecosystem, pool, and scenario. The results will permit the evaluation of a range of policies, mitigation options, and research topics, such as the demographic, LULC-change, or climate-change effects on carbon stocks, carbon sequestration, and GHG fluxes in ecosystems.

Scientific Investigations Report↗
USGS2013

Reconnaissance investigation of the rough diamond resource potential and production capacity of Côte d’Ivoire

Ethnic and political conflict developed into open civil war in Côte d’Ivoire in 2002, leading to a de facto partitioning of the country into the government-controlled south and the rebel-controlled north. Côte d’Ivoire’s two main diamond mining areas, Séguéla and Tortiya, are located in the north, under what was, until recently, rebel-controlled territory. In an effort to prevent proceeds from diamond mining from funding the conflict, the United Nations (UN) placed an embargo on the export of rough diamonds from Côte d’Ivoire in 2005. That same year, the Kimberley Process (KP), the international initiative charged with stemming the flow of conflict diamonds, acted to enforce this ban by adopting the Moscow Resolution on Côte d’Ivoire, which contained measures to prevent the infiltration of Ivorian diamonds into the legitimate global rough diamond trade. Though under scrutiny by the international community, diamond mining activities continued in Côte d’Ivoire, with artisanal miners exploiting both alluvial deposits in fluvial systems and primary kimberlitic dike deposits. However, because of the embargo, there has been no official record of diamond production since the conflict began in 2002. This lack of production statistics represents a significant data gap and hinders efforts by the KP to understand how illicitly produced diamonds may be entering the legitimate trade. This study presents the results of a multiyear effort to monitor the diamond mining activities of Côte d’Ivoire’s two main diamond mining areas, Séguéla and Tortiya. An innovative approach was developed that integrates data acquired from archival reports and maps, high-resolution satellite imagery, and digital terrain modeling to assess the total diamond endowment of the Séguéla and Tortiya deposits and to calculate annual diamond production from 2006 to 2013. On the basis of currently available data, this study estimates that a total of 10,100,000 carats remain in Séguéla and a total of 1,100,000 carats remain in Tortiya. Production capacity was calculated for the two study areas for the years 2006–2010 and 2012–2013. Production capacity was found to range from between 38,000 carats and 375,000 carats in Séguéla and from 13,000 carats and 20,000 carats in Tortiya. Further, this study demonstrates that artisanal mining activities can be successfully monitored by using remote sensing and geologic modeling techniques. The production capacity estimates presented here fill a significant data gap and provide policy makers, the UN, and the KP with important information not otherwise available.

Scientific Investigations Report↗
USGS2018

Temporal and spatial monitoring of cyanobacterial blooms at Willow Creek Reservoir, North-Central Oregon

The U.S. Geological Survey (USGS) and U.S. Army Corps of Engineers (USACE) investigated the spatial and temporal dynamics of cyanobacterial (blue-green algal) blooms in Willow Creek Reservoir in north-central Oregon in 2015–16. A combination of cameras and water-quality monitoring equipment was used to assess the frequency and duration of blooms and their effects on water quality. A surveillance camera captured color images every 15 minutes during daylight hours of the northwestern corner of Willow Creek Reservoir, where surface blooms tend to accumulate due to the prevailing summer winds. In 2015, a water-quality instrument was deployed in the northwestern corner of the reservoir to continuously measure water temperature, pH, dissolved oxygen, specific conductance, turbidity, total chlorophyll, and the blue-green algae pigment phycocyanin. In 2016, a water-quality instrument was used to collect measurements along transects throughout the reservoir to create spatial maps of water quality. The spatially integrated mapping process was repeated on three different days under varying algal conditions. Also in 2016, a telemetry connection was established allowing resource managers to view the reservoir images in near-real time. Results from 2015 indicate that surface accumulations of cyanobacteria can form and dissipate within minutes in the reservoir, and that blooms can cause substantial changes to water quality. A persistent cyanobacterial bloom in August and September 2015 resulted in pH values of 9.5 standard units, 220 percent oxygen saturation, and pronounced increases in turbidity and total chlorophyll. The stationary water-quality instrument collected data during periods with and without blooms, increasing our understanding of the effects of blooms on water quality and revealing potential restoration benchmarks for the freshwater reservoir. The spatially integrated mapping data showed the variation in water quality across the reservoir that occurs during blooms and baseline conditions and indicated regions of the reservoir to focus restoration efforts. Additional spatial data collection can be timed to collect daily extremes. The camera deployment in 2016 demonstrated that telemetering images from remote sites is possible and provides valuable and timely information. Monitoring with a surveillance camera is inexpensive and supplies data regarding surface-bloom presence or absence. The use of a camera can help target site visits to periods when blooms are observed, which may increase the accuracy of beginning and ending dates for water body closures. Monitoring cyanobacterial blooms in Willow Creek Reservoir with multiple devices provided a more comprehensive dataset than any one monitoring method. The camera images showed when a surface bloom initiated and dissipated while the water-quality instrument revealed the magnitude, or potential severity, of the effects on water quality.

Oregon↗
USGS2008

Proceedings of the U.S. Geological Survey Seventh Biennial Geographic Information Science Workshop, Denver, Colorado, May 12-16, 2008

The U.S. Geological Survey (USGS) Seventh Biennial Geographic Information Science (GIS) Workshop (USGS-GIS 2008) on May 12 through 16, 2008, at the Denver Federal Center in Denver, Colorado, is unique in that it brings together GIS professionals from all of the USGS disciplines across all regions, and focuses primarily on the needs and accomplishments of the USGS. The theme for the 2008 workshop, “GIS for Tomorrow’s Challenges,” provides an opportunity for USGS GIS professionals to demonstrate how they have responded to the challenges set forth in the USGS Science Strategy (http://www.usgs.gov/science_ strategy/). During this workshop, attendees will have an opportunity to present or demonstrate their work; develop their knowledge by attending hands-on workshops and presentations given by professionals from the USGS and other Federal agencies, GIS-related companies, and academia; and to network with other professionals to develop collaborative opportunities. In addition to participation in numerous workshops and presentations, attendees will have opportunities to listen to top-level managers from the USGS present updates and goals concerning the future of several USGS programs. Monday evening’s Star Guest presentation by Thomas Wagner, NSF Office of Polar Programs, and Paul Morin, Antarctic Geospatial Information Center, entitled “Mapping all that is White: Antarctic Science and Operations Viewed Though Geospatial Data,” will be one of many valuable presentations. This Proceedings volume will serve as an activity reference for workshop attendees, as well as an archive of technical abstracts presented at the workshop. Author, co-author, and presenter names, affiliations, and contact information are listed with presentation titles with the abstracts. Some hands-on sessions are offered twice; in these instances, abstracts submitted for publication are presented in the proceedings on both days on which they are offered. All acronyms used in these proceedings are explained in the text of each abstract.

Scientific Investigations Report↗
USGS2010

Groundwater resources of the East Mountain area, Bernalillo, Sandoval, Santa Fe, and Torrance Counties, New Mexico, 2005

The groundwater resources of about 400 square miles of the East Mountain area of Bernalillo, Sandoval, Santa Fe, and Torrance Counties in central New Mexico were evaluated by using groundwater levels and water-quality analyses, and updated geologic mapping. Substantial development in the study area (population increased by 11,000, or 50 percent, from 1990 through 2000) has raised concerns about the effects of growth on water resources. The last comprehensive examination of the water resources of the study area was done in 1980-this study examines a slightly different area and incorporates data collected in the intervening 25 years. The East Mountain area is geologically and hydrologically complex-in addition to the geologic units, such features as the Sandia Mountains, Tijeras and Gutierrez Faults, Tijeras syncline and anticline, and the Estancia Basin affect the movement, availability, and water quality of the groundwater system. The stratigraphic units were separated into eight hydrostratigraphic units, each having distinct hydraulic and chemical properties. Overall, the major hydrostratigraphic units are the Madera-Sandia and Abo-Yeso; however, other units are the primary source of supply in some areas. Despite the eight previously defined hydrostratigraphic units, water-level contours were drawn on the generalized regional potentiometric map assuming all hydrostratigraphic units are connected and function as a single aquifer system. Groundwater originates as infiltration of precipitation in upland areas (Sandia, Manzano, and Manzanita Mountains, and the Ortiz Porphyry Belt) and moves downgradient into the Tijeras Graben, Tijeras Canyon, San Pedro synclinorium, and the Hagan, Estancia, and Espanola Basins. The study area was divided into eight groundwater areas defined on the basis of geologic, hydrologic, and geochemical information-Tijeras Canyon, Cedar Crest, Tijeras Graben, Estancia Basin, San Pedro Creek, Ortiz Porphyry Belt, Hagan Basin, and Upper Sandia Mountains. View report for unabridged abstract.

Scientific Investigations Report↗