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At least 109 records · Page 6Linked to original sources
USGS2002

Generalized surficial geologic map of the Pueblo 1° x 2° quadrangle, Colorado

Fifty-three types of surficial geologic deposits and residual materials of Quaternary age are described in a pamphlet and located on a map of the greater Pueblo area, in part of the Front Range, in the Wet and Sangre de Cristo Mountains, and on the plains east of Colorado Springs and Pueblo. Deposits formed by landslides, wind, and glaciers, as well as colluvium, residuum, alluvium, and others are described in terms of predominant grain size, mineral or rock composition (e.g., gypsiferous, calcareous, granitic, andesitic), thickness, and other physical characteristics. Origins and ages of the deposits and geologic hazards related to them are noted. Many lines drawn between units on our map were placed by generalizing contacts on published maps. However, in 1997-1999 we mapped new boundaries as well. The map was projected to the UTM projection. This large map area extends from near Salida (on the west edge), eastward about 107 mi (172 km), and from Antero Reservoir and Woodland Park on the north edge to near Colorado City at the south edge (68 mi; 109 km).

Colorado↗
USGS1972

Documentation and environment of the Apollo 16 samples a preliminary report

This catalog is a working document that shows the locations from which samples were collected during the Apollo 16 mission, and that provides a descriptive geologic context for each sample. It is a compilation of notes from work in progress, and supersedes an earlier report prepared by the Apollo Lunar Geology Investigation Team. The information in this report was obtained from the Air-to-Ground transcript from the astronaut crew, from lunar surface television, from 60 mm Hasselblad camera photographs, and from available LRL "mugshot" photographs of the samples. The sample descriptions are based on these sources of data, and do not reflect the more detailed examination that is presently underway in the LRL. The report is still a preliminary study due to the short time available to review the rather copious data. The rocks have yet to be examined under collimated light and checked against the lunar surface photographs to make identification certain in all cases. The original orientation of the samples will, in time, as ascertained and photographically documented, and will be the subject of a final report on sample documentation. The reader will find inconsistencies in the format throughout the report (and probably some errors). But we believe that it is more important to disseminate these data early rather than to delay with detailed editing sufficient to completely standardize the format.

Open-File Report↗
USGS1987

Mapping contact metamorphic aureoles in Extremadura, Spain, using Landsat thematic mapper images

In the Extremadura region of western Spain, Ag, Pb, Zn, and Sn deposits occur in the pieces of late Hercynian granitic plutons and near the pluton contacts in late Proterozoic slate and metagraywacke that have been regionally metamorphosed to the green schist facies. The plutons generally are well exposed and have distinctive geomorphological expression and vegetation; poor exposures of the metasedimentary host rocks and extensive cultivation, however, make delineation of the contact aureoles difficult. Landsat Thematic Mapper (TM) images have been used to distinguish soil developed on the contact metamorphic rocks from soil formed on the stratigraphically equivalent slate-metagraywacke sequence. The mineral constituents of these soils are similar, except that muscovite is more common in the contact metamorphic soil; carbonaceous material is common in both soils. Contact metamorphic soil have lower reflectance, especially in the 1.6-micrometers wavelength region (TM 5), and weaker Al-OH, Mg-OH, and Fe 3+ absorption features than do spectra of the slate-metagraywacke soil. The low-reflectance and subdued absorption features exhibited by the contact metamorphic soil spectra are attributed to the high absorption coefficient f the carbonaceous material caused by heating during emplacement of the granitic plutons. These spectral differences are evident in a TM 4/3, 4/5, 3/1 color-composite image. Initially, this image was used to outline the contact aureoles, but digital classification of the TM data was necessary for generating internally consistent maps of the distribution of the exposed contact metamorphic soil. In an August 1984, TM scene of the Caceras area, the plowed, vegetation-free fields were identified by their low TM 4/3 values. Then, ranges of TM 4/5 and 3/1 values were determine for selected plower fields within and outside the contact aureoles; TM 5 produced results similar to TM 4/5. Field evaluation, supported by X-ray diffraction and petrographic studies, confirmed the presence of more extensive aureoles than shown in published geologic maps; few misclassified areas were noted. Additional plowed fields consisting of exposed contact metamorphic soil were mapped digitally in an August 1985 TM scene. Subsequently, this approach was used to map two 1-km-wide linear zones of contact metamorphosed rock and oil in the San Nicolas-Sn-W Mine area, which is located approximated 125 km southeast of the Caceras study area. Exposures of granite in the San Nicolas area are limited to a few unaltered granitic dikes in the mine and a small exposure of unaltered pegmatite-bearing granite in a quarry about 1.5 km west of the mine. The present of coarsely crystalline biotite and beryl in the granite in the quarry and of contact metamorphosed slate up to 2.5 km from the nearest granite exposure suggest that only the apical part of a pluton is exposed in the quarry and that a larger, shallowly buried body is probably present. These results indicate that potential application of TM image analysis to mineral exploration in lithologically similar areas that are cultivated in spite of poor rock exposures.

Extremadura↗
USGS1979

Analysis of ground water by different laboratories: a comparison of chloride and nitrate data, Nassau and Suffolk counties, New York

Water samples from wells in Nassau and Suffolk Counties were analyzed for chloride and nitrate. Two samples were collected at each well; one was analyzed by the U.S. Geological Survey, the other by a laboratory in the county from which the sample was taken. Results were compared statistically by paired-sample t-test to indicate the degree of uniformity among laboratory results. Chloride analyses from one of the three county laboratories differed significantly (0.95 confidence level) from that of a Geological Survey laboratory. For nitrate analyses, a significant difference (0.95 confidence level) was noted between results from two of the three county laboratories and the Geological Survey laboratory. The lack of uniformity among results reported by the participating laboratories indicates a need for continuing participation in a quality-assurance program and exercise of strong quality control from time of sample collection through analysis so that differences can be evaluated. (Kosco-USGS)

Open-File Report↗
USGS2009

Database of the geologic map of North America— Adapted from the map by J.C. Reed, Jr. and others (2005)

Introduction The Geological Society of America's (GSA) Geologic Map of North America (Reed and others, 2005a; 1:5,000,000) shows the geology of a significantly large area of the Earth, centered on North and Central America and including the submarine geology of parts of the Atlantic and Pacific Oceans. This map is now converted to a Geographic Information System (GIS) database that contains all geologic and base-map information shown on the two printed map sheets and the accompanying explanation sheet. We anticipate this map database will be revised at some unspecified time in the future, likely through the actions of a steering committee managed by the GSA and staffed by scientists from agencies including those responsible for the original map compilation. Regarding the use of this product, as noted by the map's compilers: “The Geologic Map of North America is an essential educational tool for teaching the geology of North America to university students and for the continuing education of professional geologists in North America and elsewhere. In addition, simplified maps derived from the Geologic Map of North America are useful for enlightening younger students and the general public about the geology of the continent.” With publication of this database, the preparation of any type of simplified map is made significantly easier. More important perhaps, the database provides a more accessible means to explore the map information and to compare and analyze it in conjunction with other types of information (for example, land use, soils, biology) to better understand the complex interrelations among factors that affect Earth resources, hazards, ecosystems, and climate.

Data Series↗
USGS1961

Drainage basins, channels, and flow characteristics of selected streams in central Pennsylvania

The hydraulic, basin, and geologic characteristics of 16 selected streams in central Pennsylvania were measured for the purpose of studying the relations among these general characteristics and their process of development. The basic parameters which were measured include bankfull width and depth, channel slope, bed material size and shape, length of stream from drainage divide, and size of drainage area. The kinds of bedrock over which the streams flow were noted. In these streams the bankfull channel is filled by flows approximating the 2.3-year flood. By measuring the breadth and mean depth of the channel, it was possible to compute the bankfull mean velocity for each of the 119 sampling stations. These data were then used to compute the downstream changes in hydraulic geometry of the streams studied. This method has been called an indirect computation of the hydraulic geometry. The results obtained by the indirect method are similar to those of the direct method of other workers. The basins were studied by examining the relations of drainage area, discharge, and length of stream from drainage divide. For the streams investigated, excellent correlations were found to exist between drainage area and the 2.3-year flood, as well as between length of stream from the basin divide and drainage area. From these correlations it is possible to predict the discharge for the 2.3-year flood at any arbitrary point along the length of the stream. The long, intermediate, and short axes of pebbles sampled from the bed of the stream were recorded to study both size and sphericity changes along individual streams and among the streams studied. No systematic downstream changes in sphericity were found. Particle size changes are erratic and show no consistent relation to channel slope. Particle size decreases downstream in many streams but remains constant or increases in others. Addition of material by tributaries is one factor affecting particle size and another is the parent material. Wear does not appear to account for some of the changes noted in particle size in a downstream direction. Comparison with laboratory studies indicates that at least in some streams the downstream decrease in size is much greater than would be expected from wear alone. The type of bedrock underlying the channels included in this study appears to affect both channel slope and particle size. For a given length of stream, a stream channel underlain by sandstone tends to have a steeper slope and larger bed material than channels underlain by shale or limestone. Hence, a stream which heads in sandstone and ends in limestone tends to have a more rapid decrease in slope and particle size than a stream heading in limestone and ending in sandstone. The association of steep slopes and small particles for limestone channels implies that slope and particle size may show a vague correlation between lithologic groups although no correlation may exist within a given lithologic type. In addition to the effect of bedrock on slope and particle size, there is some evidence that channels in limestone or dolomite have a slightly smaller cross section at bankfull stage than channels in shale or sandstone. Near the headwaters of many of these streams, a deposit of periglacial rubble affects the slope and bed material size. Some of the debris contains residual boulders which are too large to be moved by ordinary floods and, therefore, impose larger particle sizes in the bed of the stream. The addition of this very coarse debris to the bed material is another example of the influence of geologic factors on stream channels even though the channel consists of unconsolidated debris instead of bedrock. The influence of geologic factors noted in selected streams in central Pennsylvania may not be directly applicable to areas other than the Appalachian Mountains, but the general process is no doubt similar in most areas. In large alluvial valleys bedrock cannot be much of an influencing factor; yet large, thick alluvial deposits and terraces are in a sense "bedrock" materials upon which the stream works to form the landscape.

Pennsylvania↗
USGS1869

Preliminary Field Report of the United States Geological Survey of Colorado and New Mexico

SIR : In accordance with your instructions dated Washington, April 1, 1869, I have the honor to transmit my preliminary field report of the United States geological survey of Colorado and New Mexico, conducted by me, under your direction, during the past season. A portion of your instructions is as follows : “You will proceed to the field of your labors as soon as the necessary arrangements can be made and the season will permit, and your attention will be especially directed to the geological, mineralogical and agricultural resources of the Territories herein designated; you will be required to ascertain the age, order of succession, relative position, dip, and comparative thickness of the different strata and geological formations, and examine with care all the beds, veins, and other deposits, of ores, coals, clays, marls, peat, and other mineral substances, as well as the fossil remains of the different formations; and you will also make full collections in geology, mineralogy, and paleontology, to illustrate your notes taken in the field.”

Colorado, New Mexico↗
USGS1947

Preliminary report on the stratigraphy and structure of the area of the Utukok River with notes on the Corwin-Cape Beaufort region, Alaska

U.S. Geological Survey Party 3 studied the geology of the Utukok River area and conducted a short reconnaissance of the Corwin-Cape Beaufort Region during the period May 12 to August 31, 1947. The upper part of the Utukok River was examined for several miles on either side while the lower, or Coastal Plain-portion, was necessarily limited to the few outcrops along the river. During this study, the major emphasis was placed upon rocks of Upper Cretaceous age and their relationships to the underlying Lower Cretaceous rocks. All macrofossils, and numerous samples for porosity, heavy mineral, and microfossil determinations were collected. A triangulation net was established by theodolite from Camp. 1 near the headwaters of the river to the mouth of Carbon Creek. The survey started and ended on measured base lines, and stations were determined by intersection and resection. Stations were selected, insofar as possible, on points that could be pin pricked on aerial photographs where adequate coverage was available, Horizontal control was computed for cartographic purposes. Vertical differences were computed from an elevation at Camp 1 assumed at 2,000 feet above sea level based upon two different airplane altimeter readings. Most of the country is too rough for wheel landings with the exception of several gravel bars in the river between Camp 6 and the coast. Pontoon landings with a Cub plane can be made at most places on the river. Driftwood, Adventure, Disappointment, Carbon, and Elusive Creeks are the main tributaries to the Utukok. At various localities, terrace gravels are common on divides of these streams. A terrace north of Driftwood Creek and about ten miles east of Camp 2 is covered with a deposit of gravel which is apparently, thick and is spread over an irregular area about two miles long and a half mile wide. A thin tundra cover obscures what is probably a much larger continuation of the gravel deposit. With favorable conditions plane landings could be made, but with a little construction work a commercial size airfield could be made.

Alaska↗
USGS1970

Annotated bibliography on artificial recharge of ground water, 1955-67

Artificial ground-water recharge has become more important as water use by agriculture, industry, and municipalities increases. Water management agencies are increasingly interested in potential use of recharge for pollution abatement, waste-water disposal, and re-use and reclamation of locally available supplies. Research projects and theoretical analyses of operational recharge systems show increased scientific emphasis on the practice. Overall ground-water basin management systems generally now contain considerations of artificial recharge, whether by direct or indirect methods. Artificial ground-water recharge is a means of conserving surface runoff for future use in places where it would otherwise be lost, of protecting ground-water basins from salt-water encroachment along coastal areas, and of storing and distributing imported water. The biblio-graphy emphasizes technology; however, annotations of articles on waste-water reclamation, ground-water management and ground-water basin management are included. Subjects closely related to artificial recharge, including colloidal flow through porous media, field or laboratory instrumentation, and waste disposal by deep well injection are included where they specifically relate to potential recharge problems. Where almost the same material has been published in several journals, all references are included on the assumption that some publications may be more readily available to interested persons than others. Other publications, especially those of foreign literature, provided abstracts that were used freely as time limitations precluded obtaining and annotating all materials. Abstracts taken from published sources are noted. These are: "Abstracts of North American Geology," U.S. Department of the Interior, Geological Survey; "Abstracts of Recent Published Material on Foil and Water Conservation," ARS-41 series, Agricultural F.esearch Service, U.S. Department of Agriculture; "Water and1 Water Engineering," published by Fuel and Metallurgical Journals, Ltd., London, England; "Journal of Geophysical Research," American Geophysical Union, Washington, D.C.; "American Society of Civil Engineers Transactions," New York; "Selected Bibliography of Hydrology, United Kingdom, for the Years 1955-59," International Association of Scientific Hydrology; "Water Wells, an Annotated Bibliography," California University Water Resources Center Archives Report 13; "Re-use of Effluent in the Future With an Annotated Bibliography," by G. A. Whetstone, Texas Water Development Board Report 8, Austin, Tex.; "Journal of Water Pollution Control Federation," Washington, D.C.; and "A List of Selected Technical References on Artificial Recharge of Ground-Water Reservoirs," compiled by Roy W. Graves, Tulsa University, Information Services Department, Tulsa, Okla. Other notations are self-explanatory, and initials are those of the authors (DCS, DJG, WK). An unpublished compilation of recharge references by Arnon Arad sponsored by the United Nations Educational, Scientific, and Cultural Organization during a training period with the U.S. Geological Survey was also used. The bibliography is arranged alphabetically by author. Where an author has more than one publication, the arrangement is chronological; where an author has more than one publication in a given year, a, b, c, . . . are added. The indexing is by subject and geographic location. Each article was assigned the key words or phrases to best characterize its contents. Units of measure are as they were in the original article; abbreviations retained are generally those in common use such as mg/1 (milligrams per liter), ppm (parts per million), gpm (gallons per minute), km (kilometers), m (meters), cu m per hr (cubic meters p^r hour), cfs (cubic feet per second), me/1 (milliequivalents per liter), psi (pounds per square inch), BOD (biochemical oxygen demand), sq m (square meters), gpd (gallons per day), and mgd (million gallons per day). The bibliography was prepared because of the worldwide interest in the field of artificial recharge and the need for a single source of references to the literature published since 1954. The work is a sequel to the "Annotated Bibliography on Artificial Recharge of Ground Water Through 1954," by D. K. Todd, U.S. Geological Survey Water-Supply Paper 1477, published in 1959.

Water Supply Paper↗
USGS1919

Geology of northeastern Montana

A large region in northeastern Montana has never been thoroughly explored by geologists, owing to the fact that it is a part of the Great Plains and the belief that it is too monotonous and uninteresting to tempt anyone to turn aside from the pronounced geologic features a little farther west, for which Montana is noted. This region includes parts of Sheridan, Valley, Phillips, and Blaine counties. Its investigation was begun by Smith in 1908, when he made a geologic survey of the Fort Peck Indian Reservation. Beekly explored a strip of land along the Montana-North Dakota line from Missouri River to the international boundary, and Bauer examined the townships in which Plentywood and Scobey are situated. Their results are here included with those of the writer, who during the field seasons of 1915 and 1916 was engaged in an investigation of the lignite resources of the remainder of this region, which extends from a line within 12 miles of the Montana-North Dakota boundary westward about 200 miles.

Montana↗
USGS1996

Measurement of flows for two irrigation districts in the lower Colorado River basin, Texas

The Lower Colorado River Authority sells and distributes water for irrigation of rice farms in two irrigation districts, the Lakeside district and the Gulf Coast district, in the lower Colorado River Basin of Texas. In 1993, the Lower Colorado River Authority implemented a water-measurement program to account for the water delivered to rice farms and to promote water conservation. During the rice-irrigation season (summer and fall) of 1995, the U.S. Geological Survey measured flows at 30 sites in the Lakeside district and 24 sites in the Gulf Coast district coincident with Lower Colorado River Authority measuring sites. In each district, the Survey made essentially simultaneous flow measurements with different types of meters twice a day once in the morning and once in the afternoon at each site on selected days for comparison with Lower Colorado River Authority measurements. One-hundred pairs of corresponding (same site, same date) Lower Colorado River Authority and U.S. Geological Survey measurements from the Lakeside district and 104 measurement pairs from the Gulf Coast district are compared statistically and graphically. For comparison, the measurement pairs are grouped by irrigation district and further subdivided by the time difference between corresponding measurements less than or equal to 1 hour or more than 1 hour. Wilcoxon signed-rank tests (to indicate whether two groups of paired observations are statistically different) on Lakeside district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological Survey measurements are not statistically different. The median absolute percent difference between the flow measurements is 5.9 percent; and 33 percent of the flow measurements differ by more than 10 percent. Similar statistical tests on Gulf Coast district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological Survey measurements are not statistically different. The median absolute percent difference between the flow measurements is 2.6 percent; and 30 percent of the flow measurements differ by more than 10 percent. The differences noted above between Lower Colorado River Authority and U.S. Geological Survey measurements with 1 hour or less between measurements and the differences between essentially simultaneous U.S. Geological Survey measurements are of similar orders of magnitude and, in some cases, very close.

Texas↗
USGS1980

Preliminary aeromagnetic map of the Charlotte 1 x 2 degree quadrangle, North Carolina, South Carolina

The aeromagnetic map of the Charlotte 1 x 2 degree quadrangle was assembled by 6 individual detailed aeromagnetic surveys flown between 1956 and 1976 (see index map). The International Geomagnetic Reference Field had been subtracted from the data prior to assembly. An arbitrary common datum was selected and the surveys were recontoured at the joins. The 100 gamma contour was selected because it shows the magnetic contrast to best advantage. To complement the magnetic data a gravity survey was conducted by the U.S. Geological Survey and this data is available in a companion map (Wilson and Daniels, in press). Each of these maps has been interpreted in relation to the other and to the geologic map prepared as part of the same program (Goldsmith and others, 1978). It should be noted that the geophysics has had a measurable influence on some of the geologic mapping.

North Carolina, South Carolina↗
USGS2021

Paleozoic and Mesozoic tectonic events west of the Waterbury Dome: Results of new mapping in the western Connecticut Highlands

This field trip highlights the results of recent U.S. Geological Survey (USGS) bedrock geologic mapping in four 7.5 min quadrangles in the western Connecticut highlands near Southbury, Connecticut, USA. The rocks are broadly within what Rodgers (1985) called the Hartland and Gneiss Dome belts of the Connecticut Valley Synclinorium ( Rodgers, 1985 ; Fig. 1 ), the latter of which is now known as the Connecticut Valley–Gaspe Trough (Hibbard et al., 2006). The mapping occurred over two intervals: 2003–2005 and 2016–present. In the first, the goal was a detailed map of the early Mesozoic Pomperaug basin, which overlaps the four quadrangles. Portions of the basin had been separately mapped during the statewide 7.5 min quadrangle mapping campaign spanning the 1950s–1970s, resulting in an inaccurate depiction of the basin on the 1985 state geologic map ( Rodgers, 1985 ). A new map of the basin was proposed in part to benefit an ongoing project by the USGS Connecticut Water Science Center to determine the contributions of natural and artificial contaminants to a public water-supply well in Woodbury, Connecticut, under the National Water-Quality Assessment (NAWQA) Program ( Starn and Brown, 2007) . The NAWQA project was partially funded by the Pomperaug River Watershed Coalition, which also provided logistical support to the geologic mapping project. Mapping of the basin was also a high priority for the Connecticut State Geologist at the time (Ralph Lewis, 2002, pers. comm.). The mapping resulted in an NEIGC (New England Intercollegiate Geologic Conference) field guide ( Burton et al., 2005) and a 1:12,000-scale USGS open-file map ( Burton, 2006) and was funded by the USGS National Cooperative Geologic Mapping Program (NCGMP). The second phase of the mapping began in 2016 after the discovery of elevated levels of uranium and arsenic in domestic water wells in the igneous and metamorphic rocks that surround the sedimentary and volcanic rocks of the Pomperaug basin ( Flanagan and Brown, 2017) . Structural measurements in the surrounding crystalline rocks were made during Pomperaug basin mapping to better understand the tectonic setting, but a revision of the crystalline map units on Rodgers’ 1985 geologic map was not attempted. Nonetheless, discrepancies were noted between the new mapping and the 1985 map, particularly within the two northern quadrangles of Woodbury and Roxbury, which were originally mapped by Gates (1954) and Gates (1959) , respectively. Based on these discrepancies, a new NCGMP project was proposed to remap the Woodbury and Roxbury 7.5 min quadrangles, commencing in the fall of 2016. The expected USGS product will be a two-quadrangle, 1:24,000-scale Scientific Investigations Map (SIM). This field guide is not meant as a comprehensive review of all of the geologic research done in this area of Connecticut; rather, it looks at previous bedrock geologic mapping from the perspective of new and recent mapping in the four-quadrangle area and discusses the structural, stratigraphic, and nomenclatural revisions necessary for the next revision of the state geologic map.

Connecticut↗
USGS2025

Note to banders, February 2025

Note to All Banders was a special extra communication with more urgent information relevant to banders. This Note to All Banders was sent to U.S. bird banders on February 12, 2025. This note includes a review of the 2024 successes at the Bird Banding Laboratory. Throughout 2024, the BBL increased communication, engagement, and collaboration, within the Eastern Ecological Science Center, U.S. Geological Survey, and with organization partners and local communities. This Note to Banders highlights these efforts in more detail.

Memo to All Banders (MTAB)↗
USGS2022

Note to Banders, December 2022

Note to All Banders was a special extra communication with more urgent information relevant to banders. This Note to All Banders was sent to U.S. bird banders on December 20, 2022. This note includes holiday greetings and a review of the 2022 successes at the Bird Banding Laboratory. Throughout 2022, the BBL increased communication, engagement, and collaboration, within the Eastern Ecological Science Center, U.S. Geological Survey, and with organization partners and local communities. This Note to Banders highlights these efforts in more detail.

Newsletter↗
USGS2024

Note to All Banders - January 2024

Note to All Banders was a special extra communication with more urgent information relevant to banders. . This note includes holiday greetings and a review of the 2023 successes at the Bird Banding Laboratory. Throughout 2022, the BBL increased communication, engagement, and collaboration, within the Eastern Ecological Science Center, U.S. Geological Survey, and with organization partners and local communities. This Note to All Banders highlights these efforts in more detail.

Newsletter↗
USGS2019

Determination of study reporting limits for pesticide constituent data for the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project, 2004–2018—Part 1: National Water Quality Schedules 2003, 2032, or 2033, and 2060

The California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) is a long-term cooperative project designed to assess the quality of groundwater resources used for public and domestic drinking water supplies in the State of California, to monitor and evaluate changes to that quality, to investigate the human and natural factors controlling water quality, and to improve the availability of comprehensive groundwater quality data and information. Between May 18, 2004, and May 3, 2018, the GAMA-PBP collected 3001 groundwater samples for analysis of pesticide constituents by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL)(note that ‘pesticide constituents’ includes parent compounds and degradates). Of these samples, 2994 were analyzed for pesticide constituents on schedules 2003, 2032, or 2033 (65 to 84 constituents), and 840 were analyzed for pesticide constituents on schedule 2060 (58 constituents). The original dataset reported by the NWQL to the USGS National Water Information System (NWIS) database contained a total of 2,688 detections of 78 pesticide constituents and 253,825 non-detections. In this original dataset, 33 percent of the 3,001 samples analyzed had reported detections of one or more pesticide constituents. This report describes the GAMA-PBP data-quality objectives for pesticide data, the procedures used to establish study reporting limits, and use of those reporting limits to censor the data from the NWQL so that the final data published by the GAMA-PBP meet these data-quality objectives. The final GAMA-PBP dataset for samples collected from May 2004 to May 2018, after censoring, had a total of 1,632 detections of 37 pesticide constituents. In the final GAMA-PBP dataset, 25 percent of the 3,001 samples analyzed had detections of one or more pesticide constituents. The presence of pesticides in groundwater is commonly evaluated by calculating detection frequencies. Detection frequencies for pesticides are sensitive to detection limits and method performance for concentrations near those limits; therefore, the two primary data quality issues addressed in the GAMA-PBP data-quality objectives for pesticides are (1) establishing criteria for classifying data from the laboratory as detections or non-detections for the purpose of data reporting by the project and (2) accounting for changes in analytical methods or method performance over time. The GAMA-PBP addresses these issues by developing study reporting limits that are used as the boundary between detections and non-detections for the reporting of GAMA-PBP results. These reporting limits are defined from method detection limits (MDLs) provided by the NWQL, unless examination of results from laboratory set blanks (LSBs) and GAMA-PBP field blanks indicates that a higher concentration censoring limit is warranted. The GAMA-PBP selected the MDL as the primary choice for defining study reporting limits for consistency with U.S. Environmental Protection Agency (EPA) guidelines for reporting detections of pesticides and other organic constituents. A five-step procedure is used to develop study reporting limits and censor the GAMA-PBP dataset accordingly. The effect of the censoring at each step is described to provide information about the relative effect of each step on the overall censoring of the dataset. Steps 1 and 2 can be implemented at the time the data are received, whereas steps 3−5 require information accumulated over an extended period. Step 1: Reject results that were most likely the result of specific contamination instances attributable to unusual field or laboratory conditions during sample collection or processing. Two such instances were identified, leading to rejection of 25 detections, which were assigned a data-quality indicator code of “Q” for “reviewed and rejected” in the NWIS database. Step 2: Use the NWQL MDLs in effect at the time each sample was analyzed as the reporting limit. A total of 506 detections were censored on this basis. Step 3: Use the maximum MDL established by the NWQL during July 2004–August 2018 (MDLmax) as the reporting limit. The rationale for using the MDLmax as the reporting limit is based primarily on the observation that the concentrations of MDLs generally increased over time. A total of 438 detections were censored on this basis. Step 4: Use the LSBs to identify periods of greater potential laboratory contamination bias and define raised reporting limits to be used during those periods. These periods were defined by using a moving average detection frequency approach. For consistency with the NWQL procedures for defining raised reporting limits on the basis of detections in LSBs, the raised reporting limits were defined as equal to three times the highest concentration measured in an LSB during the period. A total of 25 detections in groundwater samples analyzed during periods of increased laboratory contamination bias were censored. Step 5: Use the LSBs and field blanks to identify potential contamination bias from field or laboratory processes outside of the time periods identified in step 4. The NWQL protocols were used to define the MDLs from blanks analyzed outside of the periods identified in step 4. If an MDL defined from blanks was greater than the MDLmax, the MDL defined from blanks was used to censor the data. One constituent had a study reporting limit defined on this basis, and a total of 62 detections in groundwater samples were censored. As of 2019, the USGS NWIS database does not have the capability to store both the original value reported by the NWQL and the final value published by the GAMA-PBP that reflects application of the quality-control censoring described in this report. In the interim, while this capability is developed, the 1,031 results censored in steps 2−5 are blocked from public release in NWIS, and the GAMA-PBP has published the original and final values in a USGS data release accompanying this report. The entire GAMA-PBP final dataset for pesticide constituents on schedules 2003, 2032, or 2033, or on schedule 2060 is publicly available in that USGS data release, through the USGS GAMA-PBP public web portal, and through the California State Water Resources Control Board GAMA public groundwater information system.

California↗
USGS2011

The Alaska Geochemical Database: v. 1.0 - Geologic Materials

What is the AGDB?: The Alaska Geochemical Database (AGDB) is a new, comprehensive compilation of geologic, spatial, descriptive, mineralogical, and analytical geochemical data for samples collected in Alaska and surrounding waters by the U.S. Geological Survey (USGS) from 1962 to 2009. Data for geologic materials (rocks, minerals and mineral separates, soils, lake sediments, bulk stream sediments, and a variety of heavy-mineral concentrates) will be released as a two-sided DVD (USGS Digital Data Series DS 637 v. 1.0) in October of 2011. Future data releases will include water, organic and leachate samples. The AGDB contains all Alaskan data from USGS legacy databases (for example, the RASS and PLUTO systems), and all results produced by USGS in-house and contract chemistry laboratories through December 2009. The database includes geochemical data resulting from the reanalysis of archived materials, such as those from the Alaska Mineral Resource Assessment (AMRAP) and National Uranium Resource Evaluation (NURE) programs, for additional elements and by newer methods. Reanalyses include samples collected statewide as part of the National Geochemical Survey, and samples from a project across the Alaska Range (data released in 2010). The AGDB also contains data for geologic materials from Alaska submitted by USGS researchers to non-USGS and non-contract labs, and a variety of other Alaskan geologic materials samples. Quality Control: Data in the AGDB have undergone extensive quality control screening including searching field notes and maps for accurate location information, verifying media and sample type, linking analytical data to geologic parameters recorded by the submitter, and documenting sample preparation and analytical methods. Data Files The AGDB v. 1.0 two-sided DVD includes: * a 4.3 GB Microsoft Access® 2007 relational database (as two linked .mdb files); * the same database in Microsoft Access® 2003; * Microsoft Excel® spreadsheet tables (.xls files) and ASCII text files that display the results of common queries to the database (for example, Ag-Cr values for concentrate samples; rock samples by quadrangle); * references for analytical methods; * references to published data; and * metadata in three file formats. Data Availability: * The Alaska Geochemical Database will be available in a searchable, spatially referenced, online format at http://mrdata.usgs.gov/; estimated availability early 2012. * A 2012 update (AGDB v. 2.0) will include water, organic, leachate, and miscellaneous sample media. For More Information: On sample media or analytical methods: http://minerals.cr.usgs.gov/projects/analytical_chem/references.html Text prepared by Jeanine M. Schmidt and Matt Granitto Figure prepared by Nora Shew; Layout by Jeanine Schmidt Artwork on page 1 by Daniel Granitto (used by permission) The USGS Mineral Resources Program is the sole Federal provider of research and information on nonfuel mineral resources.

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