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At least 451 records · Page 25Linked to original sources
USGS2012

The problem of groundwater discharge into the seas

Introductory Note: The dynamic equilibrium of the various factors involved in the world water balance or budget is the central scientific problem of the International Hydrological Decade. One of the potentially vital elements of the balance is groundwater discharge to the oceans. To paraphrase the authors of the following Russian publication, the world water budget can't be properly balanced, statically or dynamically, until there are improved values for the amount of groundwater that is discharged directly to oceans, seas, and enclosed lakes. The following report, with its bibliography, presents some Russian approaches to the problem and provides a few bits of numerical information. The report was translated by Frank W. Trainer of the U.S. Geological Survey. The text has been slightly reduced in the interests of saving space but the bibliography is given in full and has been transcribed into more or less standard U.S. Geological Survey bibliographical style. ©1971. American Geophysical Union. All Rights Reserved.

Eos, Transactions, American Geophysical Union↗
USGS1963

Ground-water data: Beaver, Escalante, Cedar City, and Parowan Valleys; parts of Washington, Iron, Beaver, and Millard Counties, Utah

This report is intended to serve two purposes: (1) to make available to the public basic ground-water data useful in planning and studying development of water resources, and (2) to supplement an interpretive report that will be published later. Records were collected during the period 1935-62 by the U.S. Geological Survey in cooperation with the Utah State Engineer as part of the investigation of ground-water conditions in the Beaver, Escalante, Cedar City, and Parowan Walleys. This report will include records collected subsequent to data published in earlier reports listed in the bibliography. The interpretive material will be published in a companion report by George W. Sandberg. This report is most useful in predicting conditions likely to be found in areas that are being considered as well sites. The person considering the new well can spot the proposed site on plate 1 and examine the records of nearby wells as shown in the tables and figure 2. From table 1 he can note such things as diameter, depth, water level, yield, use of water, and depth to aquifers in wells in the vicinity, and from the well logs in table 3 he can note the type of material that yields water to the wells. Table 2 gives several years record of yields and pumping levels of irrigation wells, and in table 4 are the chemical analyses of water from wells and springs. Figure 2 shows the historic fluctuations and trends of water levels in the four valleys. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the State Engineer. During the past several years, however, the State Engineer has rejected new applications to appropriate water in major portions of Beaver Valley, Milford and Beryl-Enterprise districts in Escalante Valley, and Cedar City Valley. Anyone seeking to initiate a new ground-water right in any of these areas should obtain information from the State Engineer's Office in either Salt Lake City or Cedar City to determine the likelihood of approval of the required application. The report is also useful when planning large-scale developments of water supply. This and other uses of the report will be helped by use of the interpretive report upon its release.

Utah↗
USGS2002

A statistical model for estimating stream temperatures in the Salmon and Clearwater River basins, central Idaho

A water-quality standard for temperature is critical for the protection of threatened and endangered salmonids, which need cold, clean water to sustain life. The Idaho Department of Environmental Quality has established temperature standards to protect salmonids, yet little is known about the normal range of temperatures of most Idaho streams. A single temperature standard for all streams does not take into account the natural temperature variation of streams or the existence of naturally warm waters. To address these issues and to help the Idaho Department of Environmental Quality revise the existing State temperature standards for aquatic life, temperature data from more than 200 streams and rivers in the salmon and Clearwater River Basins were collected. From these data, a statistical model was developed for estimating stream temperatures on the basis of subbasin and site characteristics and climatic factors. Stream temperatures were monitored hourly for approximately 58 days during July, August, and September 2000 at relatively undisturbed sites in subbasins in the Salmon and Clearwater River Basins in central Idaho. The monitored subbasins vary widely in size, elevation, drainage area, vegetation cover, and other characteristics. The resulting data were analyzed for statistical correlations with subbasin and site characteristics to establish the most important factors affecting stream temperature. Maximum daily average stream temperatures were strongly correlated with elevation and total upstream drainage area; weaker correlations were noted with stream depth and width and aver-age subbasin slope. Stream temperatures also were correlated with certain types of vegetation cover, but these variables were not significant in the final model. The model takes into account seasonal temperature fluctuations, site elevation, total drainage area, average subbasin slope, and the deviation of daily average air temperature from a 30-year normal daily average air temperature. The goodness-of-fit of the model varies with day of the year. Overall, temperatures can be estimated with 95-percent confidence to within approximately plus or minus 4 degrees Celsius. The model performed well when tested on independent stream-temperature data previously collected by the U.S. Geological Survey and other agencies. Although the model provides insight into the natural temperature potential of a wide variety of streams and rivers in the Salmon and Clearwater River Basins, it has limitations. It is based on data collected in only one summer, during which temperatures were higher and streamflows were lower than normal. The effects of changes in streamflow on the effectiveness of the model are not known. Because the model is based on data from minimally disturbed or undisturbed streams, it should not be applied to streams known to be significantly affected by human activities such as disturbance of the streambed, diversion and return of water by irrigation ditches, and removal of riparian vegetation. Finally, because the model is based on data from streams in the Salmon and Clearwater River Basins and reflects climatological and landscape characteristics of those basins, it should not be applied to streams outside this region.

Idaho↗
USGS1972

Surface water map of the Salina quadrangle, Utah

This map shows streamflow measured in acre-feet (1 acre-foot Is the amount of water that would cover an area of one acre to a depth of one foot – 43,560 cubic feet or about 326,700 gallons). Streamflow is measured and recorded by the U.S. Geological Survey at gaging stations located at the centers of the blue circles shown on the map. Average annual streamflow is shown by the size of the circles and by numbers indicating acre-feet. Distribution of flow for months of the year is shown by histograms; at most stations, flow is greatest in May and June because of runoff from melting snowing the high country in the western part of the quadrangle. Bars from left to right in the histograms run from October of one calendar year to September of the following year ( water year ). Years from 1940 to 1970 for which measurements were taken and for which streamflow is calculated are indicated under the histograms. Note that scales at the left side of the histograms, which indicate acre-feet per month, are different for different gaging stations.

Utah↗
USGS2013

Metal prices in the United States through 2010

This report, which updates and revises the U.S. Geological Survey (USGS) (1999) publication, “Metal Prices in the United States Through 1998,” presents an extended price history for a wide range of metals available in a single document. Such information can be useful for the analysis of mineral commodity issues, as well as for other purposes. The chapter for each mineral commodity includes a graph of annual current and constant dollar prices for 1970 through 2010, where available; a list of significant events that affected prices; a brief discussion of the metal and its history; and one or more tables that list current dollar prices. In some cases, the metal prices presented herein are for some alternative form of an element or, instead of a price, a value, such as the value for an import as appraised by the U.S. Customs Service. Also included are the prices for steel, steel scrap, and iron ore—steel because of its importance to the elements used to alloy with it, and steel scrap and iron ore because of their use in steelmaking. A few minor metals, such as calcium, potassium, sodium, strontium, and thorium, for which price histories were insufficient, were excluded. The annual prices given may be averages for the year, yearend prices, or some other price as appropriate for a particular commodity. Certain trade journals have been the source of much of this price information—American Metal Market, ICIS Chemical Business, Engineering and Mining Journal, Industrial Minerals, Metal Bulletin, Mining Journal, Platts Metals Week, Roskill Information Services Ltd. commodity reports, and Ryan’s Notes. Price information also is available in minerals information publications of the USGS (1880–1925, 1996–present) and the U.S. Bureau of Mines (1926–95), such as Mineral Commodity Summaries, Mineral Facts and Problems, Mineral Industry Surveys, and Minerals Yearbook. In addition to prices themselves, these journals and publications contain information relevant to prices, which has been helpful in the preparation of this publication. Prices in this report have been graphed in 1992 constant dollars to show the effects of inflation as measured by the U.S. Bureau of Labor Statistics Consumer Price Index for All Urban Consumers, a widely used measure of overall inflation in the United States. These prices are not tabulated, but a table of the deflators used is given in an appendix. Constant dollar prices can be used to show how prices that producers receive would have less purchasing power.

Scientific Investigations Report↗
USGS1973

Contrasting compositions of the youngest Columbia River basalt flows in Union and Wallowa Counties, northeastern Oregon

Note: This paper is dedicated to Aaron and Elizabeth Waters on the occasion of Dr. Waters' retirement. Several new chemical analyses of flows confined to a structural downwarp in northeastern Oregon indicate the first reported occurrence of Late-Yakima–type basalt in the region and the close stratigraphic association of Yakima–type and Late-Yakima–type flows, as well as andesite. The andesite is the most silicic flow rock yet found on the Columbia Plateau.

Oregon↗
USGS1975

National Cartographic Information Center Newsletter No. 1

This is the first of what we hope will become a continuing series of quarterly NCIC newsletters. You, the reader, are encouraged to make comments, offer praise or criticism as the occasion warrants, send in suggestions, and contribute information or articles. In this issue, we plan to present information on NCIC's operating concepts, systems, and data base and several data acquisition notes. We also have a few words on our future plans along with a brief article on our current microfilming program and a general organizational chart designed to introduce our key personnel. We realize that with such a large amount of basically introductory material our first issue is going to be a bit on the heavy side. Bear with us now and we promise a more traditional format with a lighter editorial touch in the future.

Newsletter↗
USGS1979

A proposed U.S. resource classification system

Energy is a worldwide problem calling for worldwide communication to resolve the many supply and distribution problems. Essential to a communication problem is a definition and comparability of elements being communicated. The U.S. Geological Survey, with the cooperation of the U.S. Bureau of Mines and the U.S. Department of Energy, has devised a classification system for all mineral resources, the principles of which we believe offer the possibility of world communication. At this time several other systems, extant or under development (Potential Gas Committee of the U.S., United Nations Resource Committee, and the American Society of Testing and Materials), are internally consistent and provide easy communication linkage. The system in use by the uranium community in the United States, however, ties resource quantities to Forward-Cost dollar values rendering them inconsistent with other classifications and not therefore comparable. The paper will then develop the rationale for the new USGS resource classification and note its benefits relative to a Forward-Cost classification and its relationship specifically to other extant classifications.

Open-File Report↗
USGS2009

II.-Note on Some Appendages of the Trilobites

The results of Mr. W. S. Valiant's long search for the appendages of Trilobites have recently been made known by Mr. W. B. Matthew, who described the material sold to the Columbia College of New York by Mr. Valiant. Mr. Valiant informs me that he discovered traces of what he considered to be antennæ, and that for several years he continued collecting until he found a locality where the specimens were well preserved and showed, not only the antennæ, but legs and what he supposed to be the swimming appendages.

Geological Magazine↗
USGS1891

Index to the known fossil insects of the world, including myriapods and arachnids

With the view of furthering study in the too neglected field of fossil insects, I transmit herewith for publication the card catalogue of described fossil insects which I have used for twenty years and kept constantly up to date, and which has greatly facilitated my own researches. It is believed to be practically complete. At least where insects are figured, and in many other cases where they are the first or only references from a given locality, entries are given where only the genus, the family, or even the order is mentioned. This has been done because the early literature of fossil insects is essentially vague and general, but it should not for that reason be wholly overlooked ; and to-day our knowledge of the occurrence of insects of a particular locality, even when of recent discovery, is not infrequently confined to statements of a general nature, which, if not brought to view or mind in a list like this, would be lost sight of, while their recognition may lead to further local investigation, to the earlier benefit of science. It is in no sense a systematic catalogue, and except occasionally in the notes contains no immediate results of investigation. No questions of synonymy are settled. The entries are made as the authors quoted gave them, with only the corrections of spelling required; it follows that the same insect appears at several points, to which the student is referred by full cross-references, and that more than one insect may (though probably rarely does) figure under one name. In one or two such instances, where the same name has been given by inadvertence to two totally different creatures, the later one is separated from the earlier. For convenience' sake, the entries are grouped into large sections, nearly identical with those I have employed in my systematic review of fossil insects (Bulletin 31, U. S. Geological Survey), by which method the insects from the Primary, Secondary, and Tertiary rocks are kept distinct; but otherwise the entries are purely alphabetical under the orders. It should be noticed, however, that the vague references to groups higher than genera are brought together at the beginning of each alphabet, first the most vague, and then those which permit some alphabetization. In these cases the primary or secondary alphabetization is first by authors, second by dates, and in all cases where under one entry there is more than one date the order therein is chronological. In a previous bulletin (Bulletin 69, U. S. Geological Survey) is given a complete bibliography of the literature from which these entries are taken, and the two works are thus complementary to each other.

Bulletin↗
USGS2004

Surficial materials in the conterminous United States

Introduction: The Earth's bedrock is overlain in many places by a loosely compacted and mostly unconsolidated blanket of sediments in which soils commonly are developed. These sediments generally were eroded from underlying rock, and then were transported and deposited. In places, they exceed 1,000 ft (330 m) in thickness. Where the sediment blanket is absent, bedrock is either exposed or has been weathered to produce a residual soil. This map shows the sediments and the weathered, residual material; for ease of discussion, these are referred to here as 'surficial materials.' Certain areas on this map include a significant number of rock outcrops, which cannot be shown at the scale of the map; this is noted in the 'Description of Map Units' section. Most daily human activities occur on or near the Earth's surface. Homeowners, communities, and governments can make improved decisions about hazard, resource, and environmental issues, when they understand the nature of surficial materials and how they vary from place to place. For example, are the surficial materials upon which a home is built stable enough to resist subsidence or lateral movement during an earthquake? Do these materials support a ground water resource adequate for new homes? Can they adequately filter contaminants and protect buried aquifers both in underlying sediments and in bedrock? Are they suitable for development of a new wetland? Where can we find materials suitable for aggregate? The USGS National Cooperative Geologic Mapping Program (NCGMP) works with the State geological surveys to identify priority areas for mapping of surficial materials (for example, in areas of complex and poorly understood deposits of various sediment types, where metropolitan areas are experiencing rapid growth). To help establish these priorities, a modern, synoptic overview of the geology is needed. This map represents an overview of our current knowledge of the composition and distribution of surficial materials in the conterminous United States. (The map covers only the conterminous U.S. because similar geologic information in digital form was not readily available for Alaska and Hawaii.) The best available map has been a highly generalized depiction at 1:7,500,000-scale (about 120 miles to the inch), prepared for the USGS National Atlas (Hunt, 1979; 1986). This map is compiled at a slightly more detailed scale (about 80 miles to the inch) than Hunt (1979; 1986). We used digital methods, which enabled us to rapidly incorporate the variety of source maps available to us. State-scale geologic maps from the western United States were brought directly into this map, without expending the time needed to resolve interpretive differences among them. Therefore, abrupt changes in surficial materials are indicated along many State boundaries. This of course is an artifact of our compilation technique, and a limitation on its utility. However, this approach supports the basic premise of the map -- to provide an overview of surficial materials, and to identify areas where additional work may be needed in order to resolve scientific issues that can, in turn, lead to improved mapping.

Open-File Report↗
USGS1996

Submarine landslides

Landslides are common on inclined areas of the seafloor, particularly in environments where weak geologic materials such as rapidly deposited, finegrained sediment or fractured rock are subjected to strong environmental stresses such as earthquakes, large storm waves, and high internal pore pressures. Submarine landslides can involve huge amounts of material and can move great distances: slide volumes as large as 20,000 km3 and runout distances in excess of 140 km have been reported. They occur at locations where the downslope component of stress exceeds the resisting stress, causing movement along one or several concave to planar rupture surfaces. Some recent slides that originated nearshore and retrogressed back across the shoreline were conspicuous by their direct impact on human life and activities. Most known slides, however, occurred far from land in prehistoric time and were discovered by noting distinct to subtle characteristics, such as headwall scarps and displaced sediment or rock masses, on acoustic-reflection profiles and side-scan sonar images. Submarine landslides can be analyzed using the same mechanics principles as are used for occurrences on land. However, some loading mechanisms are unique, for example, storm waves, and some, such as earthquakes, can have greater impact. The potential for limited-deformation landslides to transform into sediment flows that can travel exceedingly long distances is related to the density of the slope-forming material and the amount of shear strength that is lost when the slope fails.

Reviews of Geophysics↗
USGS2013

Laboratory evaluation of the Level TROLL 100 manufactured by In-Situ Inc.: results of pressure and temperature tests

The Level TROLL 100 manufactured by In-Situ Inc. was evaluated by the U.S. Geological Survey (USGS) Hydrologic Instrumentation Facility (HIF) for conformance to the manufacturer’s accuracy specifications for measuring pressure throughout the device’s operating temperature range. The Level TROLL 100 is a submersible, sealed, water-level sensing device with an operating pressure range equivalent to 0 to 30 feet of water over a temperature range of −20 to 50 degrees Celsius (°C). The device met the manufacturer’s stated accuracy specifications for pressure within its temperature-compensated operating range of 0 to 50 °C. The device’s accuracy specifications did not meet established USGS requirements for primary water-stage sensors used in the operation of streamgages, but the Level TROLL 100 may be suitable for other hydrologic data-collection applications. As a note, the Level TROLL 100 is not designed to meet USGS accuracy requirements. Manufacturer accuracy specifications were evaluated, and the procedures followed and the results obtained are described in this report. USGS accuracy requirements are routinely examined and reported when instruments are evaluated at the HIF.

Open-File Report↗
USGS2021

U.S. Geological Survey Community for Data Integration 2019 Workshop Proceedings—From big data to smart data

The U.S. Geological Survey (USGS) Community for Data Integration (CDI) Workshop was held during June 3–7, 2019, at Center Green in Boulder, Colo. The theme of the workshop was “From Big Data to Smart Data” with the purpose of bringing together the community to discuss current topics, shared challenges, and steps forward to advance twenty-first century science at the USGS. The workshop agenda was driven by the needs of the CDI with topics highlighting current resources and technologies that could help attendees in their daily work. Workshop-session categories included enabling integrated science, computing in the cloud, advancing data management, releasing and preserving science outputs, and improving usability and communication. These proceedings provide documentation of the plenary talks, topical-session content and notes, posters, live demonstrations, and attendee comments from the 2019 CDI Workshop.

Open-File Report↗
USGS2008

Ground-water levels in Huron County, Michigan, 2006-07

In 1990, the U.S. Geological Survey (USGS) completed a study of the hydrogeology of Huron County, Michigan (Sweat, 1991). In 1993, Huron County and the USGS entered into a continuing agreement to measure water levels at selected wells throughout Huron County. As part of the agreement, USGS initially operated four continuous water-level recorders, installed from 1988 to 1991 on wells in Bingham (H5r), Fairhaven (H9r), Grant (H2r), and Lake Townships (H25Ar) and summarized the data collected in an annual or bi-annual report (fig. 1). The agreement was altered in 2003, and beginning January 1, 2004, only wells H9r and H25Ar retained continuous water-level recorders, while wells H2r and H5r reverted to quarterly or periodic measurement status due to budget constraints. The decision of which two wells to discontinue was based on an analysis of the intrinsic value to Huron County of data from each well. Well H2r was selected for periodic measurement at that time because it is completed in the glacial aquifer, which is absent in much of Huron County and well H5r, which is completed in the Marshall aquifer, was selected because the water level in the well is often perturbed as a result of pumpage from nearby production wells and does not always reflect baseline conditions within the aquifer. USGS also has provided training for County or Huron Conservation District personnel to measure the water level in 24 of the wells on a quarterly basis. USGS personnel accompany County or Huron Conservation District personnel on a semi-annual basis to provide a quality assurance/quality control check of all measurements being made. Water-level data collected from the wells is summarized in an annual or bi-annual report. The altitude of Lake Huron and precipitation are good indicators of general climatic conditions and, therefore, provide an environmental context for groundwater levels in Huron County. Figure 2 shows the meanmonthly water-level altitude of Lake Huron, averaged from measurements made at Essexville and Harbor Beach (National Oceanic and Atmospheric Administration, 2008), and monthly precipitation measured in Harbor Beach, Sebewaing, and Bad Axe (National Oceanic and Atmospheric Administration, Danny Costello, written commun., 2007-08). In December 2007, the water level in Lake Huron dropped to a new monthly mean low of 576.38 ft for the period from 1988 through 2007 (the previous lowwater level of 576.57 ft was measured in March 2003). The net decline in the water level of Lake Huron from January 2006 through December 2007 was 0.68 ft. In 2006, annual precipitation measured at Harbor Beach was 3.2 in. above the long-term average of 31.1 in., with 10.6 in. measured during the 2006 growing season (May through August). In 2007, annual precipitation measured at Harbor Beach was 1.4 in. below normal, with 9.7 in. measured during the growing season. In the two wells equipped with continuous waterlevel recorders, the water level rose 0.32 ft from January 1, 2006 to December 31, 2007 in well H9r, but declined 1.11 ft in well H25Ar. Curiously, well H9r is drilled adjacent to Saginaw Bay (Lake Huron), and, as previously noted, there was a 0.68 ft decline in the water level in Saginaw Bay during that period. Twenty four wells were measured on a quarterly or periodic basis from December 2005 through December 2007 (well H26 was destroyed during summer 2007 reducing the total number of wells from 25). These wells are completed in the glacial, Saginaw and Marshall aquifers, and the Coldwater confining unit. Although each quarterly or periodic measurement only provides a “snapshot” water level (measured in ft below land surface, and altitude, in ft above sea level), the data adequately define the generalized water-level trend in the aquifer near the well. Water levels in 6 quarterly-measured wells had net rises ranging from 0.09 to 1.45 ft for the period, while water levels in 18 of the wells had net declines ranging from 0.26 to 2.19 ft (tables 1 and 2; fig. 3). Period-of-record (the time period during which water levels have been measured by U.S. Geological Survey or their cooperators) minimum depths to water (high-water levels) were measured in March and December 2006 in two quarterly-measured wells completed in the Saginaw aquifer in Oliver and Sebewaing Townships, respectively. A period-of-record minimum depth to water was also recorded June 5, 2007 in well H9r, completed in the Michigan Formation/Marshall aquifer in Fairhaven Township. Period-of-record maximum depths to water were measured in September 2007 in two wells completed in the Marshall aquifer in Oliver and Dwight Townships. Notably, water levels in those two wells recovered about 1 to 3 ft between September and December 2007. No period-of-record minimum or maximum depths to water were measured in wells completed in either the glacial aquifer or the Coldwater confining unit from December 2005 through December 2007. Several external factors influence water-level trends including proximity to nearby production wells, amount and timing of precipitation events, evapotranspiration and type of prevalent ground cover, proximity of aquifer to the surface, and hydraulic characteristics of overlying geologic materials.

Michigan↗
USGS1971

Analysis of current-meter data at Columbia River gaging stations, Washington and Oregon

The U.S. Geological Survey developed equipment to measure stream velocity simultaneously with 10 current meters arranged in a vertical and to measure velocity closer to the streambed than attainable with conventional equipment. With the 10 current meters, synchronous velocities were recorded for a period of 66 minutes at 10 different depths in one vertical of one gaging-station cross section. In addition, with a current meter installed on a special bracket to allow measurements to 0.5 foot above streambed, data were obtained at two to four verticals in four gaging-station cross sections. The mean velocity determined for the 66-minute period of record was 3.30 fps (feet per second). The graphic record of velocity was analyzed on a minute-by-minute basis. It was noted that the shape of the vertical velocity curves (plot of horizontal flow velocities measured in a vertical) changed from one minute to the next, but the change seemed to be random. Velocities obtained at different depths in the, profile fluctuated significantly, with the 1-minute velocities obtained at 0.05 depth (5 percent of total depths measured from the surface at indicated vertical) showing the smallest range--0.66 fps--and those at 0.55 depth the largest range--l.22 fps. The standard deviation, expressed in feet per second, of the velocity at each point in the vertical tended to increase with depth--from 0.16 fps at 0.05 depth to a maximum of 0.24 fps at 0.75 depth. The standard deviation, expressed as a percentage of the mean velocity, ranged from about 4 percent near the surface to 11 percent at 0.95 depth. In spite of the fluctuation in mean velocity that occurred during the 66 minutes and observation period of 4 minutes yields a mean velocity that differs from the 66-minute mean by less than one-half of a percent. Determining the mean velocity by averaging the 10-point observations of the 66minute run proved to be as accurate as by plotting the vertical velocity curvy (from the averaged 10 points) and then integrating the depth-velocity profile. In comparing the velocity obtained by integrating the depth-velocity profile with the 10-point mean velocity for other field data, collected beyond that obtained during the 66-minute run, the difference ranged from -1.3 to +1.7 percent and averaged -0.2 percent. Extension of the curve below the 0.95 depth by use of a power function proved to be fairly accurate (when compared with actual measurements within this reach made with the special current-meter bracket). However, the extension did not improve significantly the accuracy of the integrated-curve mean velocity. Both the one- and two-point methods were found to agree with the 10-point velocity. In computing mean river velocity, values determined by the two-point method ranged from -1.4 to +1.6 percent when compared with the base integrated-curve mean river velocity. The one-point method yielded results that ranged from -1.9 to +4.4 percent and averaged 40.1 percent. In determining river flow by use of the midsection and mean-section methods, the mean-section method uniformly yields lower flows for the same dart.. The range in difference is from -0.2 percent to -1.6 percent, with an average difference of -0.6 percent.

Water Supply Paper↗
USGS1998

Geochemical studies of rare earth elements in the Portuguese pyrite belt, and geologic and geochemical controls on gold distribution

This report describes geochemical and geological studies which were conducted by the U.S. Geological Survey (USGS) and the Servicos Geologicos de Portugal (SPG) in the Portuguese pyrite belt (PPB) in southern Portugal. The studies included rare earth element (REE) distributions and geological and geochemical controls on the distribution of gold. Rare earth element distributions were determined in representative samples of the volcanic rocks from five west-trending sub-belts of the PPB in order to test the usefulness of REE as a tool for the correlation of volcanic events, and to determine their mobility and application as hydrothermal tracers. REE distributions in felsic volcanic rocks show increases in the relative abundances of heavy REE and a decrease in La/Yb ratios from north to south in the Portuguese pyrite belt. Anomalous amounts of gold are distributed in and near massive and disseminated sulfide deposits in the PPB. Gold is closely associated with copper in the middle and lower parts of the deposits. Weakly anomalous concentrations of gold were noted in exhalative sedimentary rocks that are stratigraphically above massive sulfide deposits in a distal manganiferous facies, whereas anomalously low concentrations were detected in the barite-rich, proximal-facies exhalites. Altered and pyritic felsic volcanic rocks locally contain highly anomalous concentrations of gold, suggesting that disseminated sulfide deposits and the non-ore parts of massive sulfide deposits should be evaluated for their gold potential.

Professional Paper↗
USGS1959

Paleozoic and mesozoic fossils in a thick stratigraphic section in the eastern Sierra Nevada, California

A thick section of metamorphosed Paleozoic and Mesozoic rocks is exposed in two roof pend- ants, one each in the Mount Morrison and Devils Postpile quadrangles in the eastern Sierra Nevada near Mammoth Lakes, Cali- fornia (Fig. 1). In the course of geologic mapping in these quadrangles by the U. S. Geo- logical Survey in co-operation with the California Division of Mines, fossils of Ordovician, Pennsylvanian, Permian(P), and Early Jurassic ages were collected from weakly metamorphosed parts of the pendants. Detailed map- ping in the Mount Morrison quadrangle has been completed by Rinehart and Ross, and a report on this area is in preparation. Similar mapping in the Devils Postpile quadrangle by Rinehart and Huber is in progress. In the part of the Devils Postpile quadrangle not yet covered in the present study, the contacts shown on the map (Fig. 1) are after Erwin (1934). Because diagnostic fossils are extremely rare in the metamorphic rocks of the Sierra Nevada, these fossils are considered important enough to merit this short note prior to completion of the detailed mapping in the Devils Postpile quadrangle and the publication of more comprehensive reports on the two quadrangles

California↗