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At least 1,459 records · Page 81Linked to original sources
USGS2006

Tracermodel1- Excel workbook for calculation and presentation of environmental tracer data for simple groundwater mixtures: Use of chlorofluorocarbons in hydrology - a guidebook; Section III.10.3

Atmospheric environmental tracers commonly used to date groundwater on timescales of years to decades include CFC-11, CFC-12, CFC-113, SF6, 85Kr, 3 H and 3 H/3 H0 , where 3 H0 refers to initial tritium (3 H + tritiogenic 3 He) (Cook and Herczeg, 2000). Interpretation of age from environmental tracer data may be relatively simple for a water sample with a single age, but the interpretation is more complex for a sample that is a mixture of waters of varying ages. A mixture can be a natural result of convergence of flow lines to a discharge area such as a spring or stream, or it can be an artefact of sampling a long-screen well. TRACERMODEL1 contains a worksheet that can be used to determine hypothetical concentrations of atmospheric environmental tracers in water samples with several different age distributions. It is designed to permit plotting of ages and tracer concentrations in a variety of different combinations to facilitate interpretation of measurements. TRACERMODEL1 includes several different types of graphs that are linked to the calculations. The spreadsheet and accompanying graphs can be modified for specific applications. For example, the selection of atmospheric environmental tracers can be changed to reflect analytes of interest, the input tracer data can be modified to reflect local conditions or different timescales, and the analytes of interest can include other types of non-point-source contaminants, such as nitrate (Böhlke, 2002). Previous versions of this workbook have been used to evaluate field data in studies of groundwater residence time and agricultural contamination (Böhlke and Denver, 1995; Focazio et al., 1998; Katz et al., 1999; Katz et al., 2001; Plummer et al., 2001; Böhlke and Krantz, 2003; Lindsey et al., 2003).

Report↗
USGS1963

Selected hydrologic data, Pavant Valley, Millard County, 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 1959-62 by the U.S. Geological Survey in cooperation with the Utah State Engineer as a part of the investigation of ground-water conditions in Pavant Valley in Millard County, Utah. The interpretive material will be published in a companion report by Reed W. Mower. 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 l and examine the records of nearby wells as shown in the tables. From tables l and 3 he can note the type of material that yields water to wells in the vicinity; from table 1 he can note (1) the depth and diameter of wells in the vicinity and the yield of some of those wells, and (2) the depth to water or the feet of water pressure in the vicinity; from table 2 he can note the historic fluctuations and trends of water levels in the vicinity; from table 4 he can note the chemical quality of the water from wells in the vicinity; and from table l he can find the use made of the well water. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the State Engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
USGS1961

Records and water-level measurements of selected wells and chemical analysis of ground water, East Shore area, Davis, Weber, and Box Elder Counties

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 1935-61 by the U.S. Geological Survey in cooperation with the Utah State Engineer as a part of the investigation of the ground-water resources of the East Shore area in Davis, Weber, and southern Box Elder Counties, Utah. During the period 1952-61 additional records were collected by the U.S. Bureau of Reclamation. The interpretive material will be published cooperatively by the U.S. Geological Survey and the Utah State Engineer as a report entitled "Groundwater conditions in the East Shore area, Utah, 1953-61," by Ralph E. Smith. 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 on the tables and figures. From table 1 he can note (1) the depth and diameter of wells in the vicinity and the yield of some of those wells, and (2) the depth to water or the feet of water pressure in wells in the vicinity; from table 2 and figure 2 he may note the historic fluctuations and trends of water levels in the vicinity; and from tables 3 and l he may note the chemical quality of the water from wells in the vicinity and the use made of this water. If the reader decides from his examination that conditions are favorable, he may place an application to drill a well with the State Engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
USGS1962

Records of selected wells and springs, selected drillers' logs of wells, and chemical analyses of ground and surface waters, northern Utah Valley, Utah County, 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 1956-59 by the U.S. Geological Survey in cooperation with the Utah State Engineer as a part of the investigation of the ground-water resources of northern Utah Walley in Utah County, Utah. Some earlier data and other information in the tables are from published reports on the ground-water resources of northern Utah Walley. The interpretive material will be published cooperatively by the U.S. Geological Survey and the Utah State Engineer in a companion report by Seymour Subitzky. 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 on the tables. From tables 1, 2, and h he can note the type of material that yields water to wells in the vicinity; from table 2 he can note (1) the depth and diameter of wells in the vicinity and the yield of some of those wells, and (2) the depth to water or the feet of water pressure in the vicinity; from table 3 and plate 1 he may note the location of springs and the conditions related to the occurrence of these springs; and from tables 5 and 6 he may note the chemical quality of the water from wells and from some surface sources, and the uses of these waters. If the reader decides from his examination that conditions are favorable, he may place an application to drill a well with the State Engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
USGS1963

Selected hydrologic data, Tooele Valley, Tooele County, 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 1958-63 by the U.S. Geological Survey in cooperation with the Utah State Engineer as part of the investigation of ground-water conditions in Tooele Valley, Tooele County, Utah. Additional data, collected prior to this study, can be found in the reports listed in the bibliography, and in the Water-Supply Papers of the Geological Survey listed at the beginning of table 2. The interpretive material will be published in a companion report by Joseph S. Gates. 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 figures. From table I he can note such things as depth, diameter, water level, yield, drawdown, use of water, temperature of water, and depth of perforations. By comparing the depth of perforations with the drillers' logs in table 3 he can note the type of material that yields water to the wells. Table 2 and figures 2, 3, and 4 show the historic fluctuations and trends of water levels in the vicinity. From table 4 he can note the chemical quality of the water from wells in the vicinity. Table 5 shows the amount of water discharged during 1962 from the pumped wells. If the reader decides from his examination that conditions are favorable he can place an application to drill a well with the State Engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
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↗
USGS1963

Ground-water data, central Sevier Valley, parts of Sanpete, Sevier, and Piute 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 1956-60 by the U.S. Geological Survey in cooperation with the Utah State Engineer as a part of the investigation of ground-water conditions in the central Sevier Valley in parts of Sanpete, Sevier, and Piute Counties, Utah. The interpretive material will be published in a companion report by Richard A. Young and Carl H. Carpenter. 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 l and examine the records of nearby wells as shown on the tables. From tables land 4 he can note the type of material that yields water to wells in the vicinity; from table 1 he can note (l) the depth and diameter of wells in the vicinity and the yield of some of those wells, and (2) the depth to water or the feet of water pressure in the vicinity; from table 3 he can note the historic fluctuations and trends of water levels in the vicinity; from table 2 and plate l he can note the location or springs and the conditions related to the occurrence of these springs; from table 5 he can note the chemical quality of the water from wells and springs in the vicinity; and from tables l and 2 he can find the use made of the well and spring water. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the state engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
USGS1963

Selected hydrologic data, Jordan Valley, Salt Lake County, 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 1956-59 by the U.S. Geological Survey in cooperation with the Utah State Engineer as a part of the investigation of Ground-water conditions in the Jordan Valley, Utah. The interpretive material Will be published in a companion report by T. lendell Marine and Don Price. 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 in plate 1 and examine the records of nearby wells as shown in the tables. From table 2 he can note the type of material that yields water to wells in the vicinity; from table l he can note (1) the depth and diameter of wells in the vicinity and the yield of some of those wells, and (2) the depth to water or the feet of water pressure in the vicinity; from table 1 and plate 1 he can note the location of springs; from tables 3 and l, he can note the chemical quality of the water from wells and springs and from surface sources in the vicinity; and from table l he can find the use made of the well and spring water. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the State Engineer. If the State Engineer believes that unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
USGS1964

Ground-water data, Sevier Desert, 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 1935-64 by the U.S. Geological survey in cooperation with the Utah State Engineer as part of the investigation of ground-water conditions in the Sevier Desert, in Juab and Millard Counties, Utah. The interpretive material will be published in a companion report by R. W. Mower and R. D. Feltis. 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 figures. From table 1 he can note such things as depth, diameter, water level, yield, use of water, temperature of water, and depth of perforations. By comparing the depth of perforations with the drillers' logs in table 3 he can note the type of material that yields water to the wells. Table 2 and figure 2 show the historic fluctuations and trends of water levels in the vicinity. From table 4 he can note the chemical quality of the water from wells in the vicinity. Table 5 shows the amount of water discharged during 1951-63 from the pumped irrigation, public supply, and industrial wells. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the state Engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
USGS1964

Selected hydrologic data, upper Sevier River basin, 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 1961-63 by the U.S. Geological Survey in cooperation with the Utah State Engineer as a part of the investigation of ground-water conditions in the upper Sevier River basin, in parts of Garfield, Iron, Kane, Piute, and Sevier Counties, Utah. The interpretive material will be published in a companion report by Carl H. Carpenter, Gerald B. Robinson, Jr., and Louis J. Bjorklund. 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 and springs as shown in the tables. From table 1 he can find information on wells, including depth, diameter, water level, yield, drawdown, use of water, temperature of water, and depth of perforations. Table 2 gives information on springs such as yield, use of water, temperature, and improvements. From tables 1 and 2 he can note the type of material that yields water in the vicinity. Table 3 shows the historic fluctuations and trends of water levels. Table 4 shows the type of material penetrated by wells. From table 5 he can note the chemical quality of water from wells and springs, and from table 6, the chemical quality of surface water. If the reader decides from his examination that conditions are favorable, he can place an application to drill a well with the State Engineer. If the State Engineer believes unappropriated water is available, the application may be approved after minimum statutory requirements have been satisfied. 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↗
USGS2009

Vegetation classification and distribution mapping report: Mesa Verde National Park

The classification and distribution mapping of the vegetation of Mesa Verde National Park (MEVE) and surrounding environment was achieved through a multi-agency effort between 2004 and 2007. The National Park Service’s Southern Colorado Plateau Network facilitated the team that conducted the work, which comprised the U.S. Geological Survey’s Southwest Biological Science Center, Fort Collins Research Center, and Rocky Mountain Geographic Science Center; Northern Arizona University; Prescott College; and NatureServe. The project team described 47 plant communities for MEVE, 34 of which were described from quantitative classification based on f eld-relevé data collected in 1993 and 2004. The team derived 13 additional plant communities from field observations during the photointerpretation phase of the project. The National Vegetation Classification Standard served as a framework for classifying these plant communities to the alliance and association level. Eleven of the 47 plant communities were classified as “park specials;” that is, plant communities with insufficient data to describe them as new alliances or associations. The project team also developed a spatial vegetation map database representing MEVE, with three different map-class schemas: base, group, and management map classes. The base map classes represent the fi nest level of spatial detail. Initial polygons were developed using Definiens Professional (at the time of our use, this software was called eCognition), assisted by interpretation of 1:12,000 true-color digital orthophoto quarter quadrangles (DOQQs). These polygons (base map classes) were labeled using manual photo interpretation of the DOQQs and 1:12,000 true-color aerial photography. Field visits verified interpretation concepts. The vegetation map database includes 46 base map classes, which consist of associations, alliances, and park specials classified with quantitative analysis, additional associations and park specials noted during photointerpretation, and non-vegetated land cover, such as infrastructure, land use, and geological land cover. The base map classes consist of 5,007 polygons in the project area. A field-based accuracy assessment of the base map classes showed overall accuracy to be 43.5%. Seven map classes comprise 89.1% of the park vegetated land cover. The group map classes represent aggregations of the base map classes, approximating the group level of the National Vegetation Classification Standard, version 2 (Federal Geographic Data Committee 2007), and reflecting physiognomy and floristics. Terrestrial ecological systems, as described by NatureServe (Comer et al. 2003), were used as the fi rst approximation of the group level. The project team identified 14 group map classes for this project. The overall accuracy of the group map classes was determined using the same accuracy assessment data as for the base map classes. The overall accuracy of the group representation of vegetation was 80.3%. In consultation with park staff , the team developed management map classes, consisting of park-defined groupings of base map classes intended to represent a balance between maintaining required accuracy and providing a focus on vegetation of particular interest or import to park managers. The 23 management map classes had an overall accuracy of 73.3%. While the main products of this project are the vegetation classification and the vegetation map database, a number of ancillary digital geographic information system and database products were also produced that can be used independently or to augment the main products. These products include shapefiles of the locations of field-collected data and relational databases of field-collected data.

Mesa Verde National Park↗
USGS1990

Ross Sea

Eight short-wavelength, seismically defined penetrative structures having associated 1- to 5-km-wide magnetic anomalies (Table A. 12.1) in the western Ross Sea (Figure A. 12.1) are interpreted as volcanic in origin. Modeled anomalies fitted to the observed data and constrained by 24-fold seismic reflection profiles support the interpretation of these submarine volcanoes. Anomaly a (Figure A. 12.1) is interpreted as a submarine caldera with an associated volcanic dome and is underlain by magma or rock above the Curie temperature [Behrendt et al, 1987].

Antarctic Research Series↗
USGS1995

Geology of Triton

Triton, with a diameter of ≡2700 km, is Neptune's only planet-class satellite. The complexity of Triton's surface and the variety of surface features is unequaled among the satellites of the solar system. From a geologic viewpoint, some of Triton's features have apparently familiar morphologies and general interpretative agreement exists. However, many of its landforms have novel morphologies and geologic settings, which have given rise to a number of innovative and competing interpretations. The first portion of this chapter describes Triton's surface in primarily nongenetic terms. The authors then review various models and speculations regarding geologic processes that have operated on Triton, followed by an interpretive stratigraphy and geologic history.

Book chapter↗
USGS2018

Correlation of the Eagle Ford Group, Woodbine Group, and equivalent Cenomanian-Turonian Mudstones using regional wireline-log cross sections across the Texas Gulf Coast, U.S.A.

As part of the U.S. Geological Survey’s 2018 hydrocarbon assessment of the Eagle Ford Group and associated Cenomanian-Turonian strata, a series of regional wireline-log cross sections were constructed to examine geologic characteristics of this stratigraphic interval across the Texas Gulf Coast from Mexico to Louisiana. The cross sections were used to help define six continuous assessment units based, in part, on stratigraphic thickness, lateral extent, and lithology. The locations of the strike and dip cross sections were selected to address questions pertinent to the hydrocarbon assessment. Stratigraphic correlation of the Eagle Ford Group and corresponding Cenomanian-Turonian mudstones has been debated for many years, and differences in interpretations remain. Formation tops published in the literature, from IHS Markit TM , as well as information from a commercial biostratigraphic database were used to define consistent criteria to construct these cross sections from interpreted wireline logs. Specific units of interest include the Austin Chalk, upper and lower Eagle Ford Group, mudstones of the Woodbine Group, and the Buda Limestone. Wireline gamma-ray (GR) logs through the Eagle Ford Group have values greater than 100 American Petroleum Institute (API) units in several areas of this study, including the Maverick Basin, the Karnes Trough, and the Brazos Basin. High GR values in mudstones may be interpreted to represent potential organic-rich intervals. These high GR zones provide a criterion to identify the lateral variability in potential Cenomanian-Turonian source rock intervals from South Texas to the Texas-Louisiana border.

Gulf Coast Association of Geological Societies Tra↗
USGS2014

Uncertainty and risk evaluation during the exploration stage of geothermal development

Quantifying and representing uncertainty for geothermal systems is often ignored, in practice, during the exploration phase of a geothermal development project. We propose that this occurs potentially because the task seems so formidable. The primary goal of this paper is to initiate a dialogue within the geothermal community about: which geothermal uncertainties should receive the most attention and which uncertainty analysis methods could provide the greatest benefit for the advancement of the geothermal energy industry. In this paper, we discuss uncertainty quantification techniques that are applicable to geothermal exploration. In general, uncertainty associated with data acquisition/processing (i.e., objective uncertainty) is small compared to the uncertainty in interpretational space (i.e., subjective uncertainty) that lies between data points where extrapolation is required. Therefore, it is important to classify, assess, and quantify uncertainty to help select strategies to reduce uncertainty, and to better gauge the impact that separate uncertainties have on the overall likelihood of project success. In addition, geostatistics provides multiple quantitative methods for producing stochastic models which adhere to measured data and spatial correlation. The petroleum industry has successfully used both geostastistics and decision analysis methods to combine diverse and multiple types of uncertainties. We argue that instead of one single and final interpretation of the geothermal system, numerous interpretations may be more indicative of the possible subsurface scenarios, and these different scenarios can be evaluated using decision analyses and value of information methodologies. Lastly, we recommend that the potential power generation of a geothermal reservoir should be grounded in the geologic data and modeling for a specific field and their estimated uncertainties. In this paper, we provide a brief overview of many of these topics while a more complete review has been recently published in Witter et al. (2019).

Conference Paper↗
USGSDate not supplied

Early Paleozoic composite melange terrane, central Appalachian Piedmont, Virginia and Maryland; Its origin and tectonic history

Two distinct types of mélange deposits, distinguished by their matrix, occur within a collage of thrust slices in the Piedmont of the central Appalachians. They crop out in a northeast-trending belt that extends from at least central Virginia northeastward through most of Maryland. One type is a block-in-phyllite mélange that constitutes the Mine Run Complex (new name) of Virginia. It consists of a variety of metaplutonic, metavolcanic, mafic, and ultramafic blocks enclosed within a matrix of phyllite or schist and metasandstones of feldspathic or quartz metagraywacke. The Mine Run Complex is interpreted to consist of four imbricated thrust slices, each with its own distinctive exotic block content. The blocks in one of these mélange subunits (III) are almost exclusively mafic and ultramafic rocks, such as serpentinite, greenschist, metabasalt, and talc schist. The second mélange type within this Piedmont terrane, a metadiamictite, contains a less extensive variety of exotic blocks, the most common being mafic and ultramafic blocks. Such exotic blocks are enclosed in a micaceous quartzofeldspathic matrix, which has contemporaneously deposited schist and quartz-lump fragments as its characterizing features. The Sykesville Formation of Maryland and Virginia is typical of this type of mélange. Several varieties of metadiamictite that have some lithologic differences from the type locality of the Sykesville have been recognized in Virginia and are described as the Lunga Reservoir and the Purcell Branch Formations (new names). Mélanges of the block-in-phyllite and the metadiamictite types are interpreted as having been formed in a Cambrian-Ordovician back-arc or marginal basin that lay on the continentward side of an island-arc system (central Virginia volcanic-plutonic belt and the James Run Formation of Maryland) that had formed in Cambrian time. This Cambrian-Ordovician back-arc basin is assumed to have been underlain, at least initially, by a transform-segmented spreading ridge. The metadiamictite deposits now occur, for the most part, along the flanks and at the southeastern end of the Baltimore-Washington anticlinorium or antiform. This spatial relation is interpreted to be a consequence of thrusting of the diamictite across, as well as onto, the cover rocks and basement of the anticlinorial core terrane (“Baltimoria”) during the Taconic orogeny. The chaotic-textured diamictite formed as a sedimentary slump or slide apron or aprons somewhere to the east of “Baltimoria.” The source area for this diamictite probably was another crystalline landmass that lay east of “Baltimoria.” The matrix rocks of the block-in-phyllite mélange (Mine Run Complex) may have accumulated contemporaneously, in part with diamictite, probably by along-trough basin sedimentation. The block-in-phyllite mélanges of the Mine Run Complex occur south of the Baltimore-Washington anticlinorium metadiamictite terrane and are not associated directly with metadiamictite mélanges. The metavolcanic and metaplutonic blocks within the eastern parts of the Mine Run Complex probably were shed from the island-arc terrane as it was thrust westward during the progressive tectonic telescoping of the back-arc basin in Cambrian and Ordovician time. The mafic and ultramafic blocks in both types of mélanges are believed to have been derived, in part, from the “oceanic” back-arc basin floor from various sources and different processes. Ultramafic protrusions, for example, may have been emplaced periodically along transform faults. Some of the mafic-ultramafic rock may have formed talus rubble along steep submarine scarps. Others may represent blocks broken and segmented by faults from what once were mafic sills emplaced within the sediments accumulating in the basin.

Maryland, Virginiia↗
USGS2003

Hydraulic logging methods - A summary and field demonstration in Conyers, Rockdale County, Georgia

Geophysical surveying techniques provide important information for ground-water investigations (Zohdy and others, 1974; Keys, 1997; Haeni and others, 2001). Subsurface-geophysical methods are used to delineate and characterize hydraulically active zones; the extent of contamination, and contaminant sources; identify geologic features; optimize monitoring well placement; and guide remediation efforts. Borehole-geophysical methods provide information about the physical, chemical, and hydraulic properties of rock, sediments, and fluids in the subsurface and provide important information on subsurface bedrock structures including lithology, rock fabric, location, orientation, and hydraulic properties of fractures (Keys, 1990). Effective use of geophysical data requires that the data be interpreted in the context of known local and regional geology and hydrogeology. In addition, because of the complexity and heterogeneity of crystalline-rock aquifers, a suite of borehole geophysical methods is used to determine the location, extent, and nature of fractures and other structural features in the bedrock aquifer. The geophysical data from each borehole and method are analyzed together to provide an integrated interpretation, thereby reducing the ambiguity that can occur by interpreting each geophysical log individually (Shapiro and others, 1999). Previous work using borehole geophysics to characterize ground-water availability in crystalline rock aquifers includes Chapman and Lane (1996), Mack and others (1998), and Johnson and others (1999). Other investigations that focused on contamination in fractured-rock aquifers used geophysical methods to relate highly transmissive features to structural features in the bedrock (Hansen and Lane, 1995; and Lane and others, 2002).

Georgia↗
USGS1987

The significance of observations at active volcanoes; A review and annotated bibliography of studies at Kilauea and Mount St. Helens

Study of active volcanoes yields information of much broader significance than to only the discipline of volcanology. Some applications are 1) interpretation of lava-flow structures, stratigraphic complexities, and petrologic relations in older volcanic units; 2) interpretation of bulk properties of the mantle and constraints on partial melting and deep magma transport; 3) interpretation of geophysical characteristics of potentially active volcanic systems; 4) direct determination of physical properties of molten and solidified basalt, and of intensive variables (e.g., oxygen fugacity and temperature) accompanying cooling and crystallization; 5) quantitative assessment of crystal fractionation and magma mixing, 6) tests of theoretical and experimental geochemical, geophysical, and rheologic models of volcanic behavior; and 7) confirmation in nature of laboratory experiments related to crystallization in igneous systems. The critical factors that make real-time study of volcanic activity valuable are that the location and timing of events are known, and that molten rock and gases are available for direct observation and sampling for subsequent study. Observations made over a period of time make it possible to calculate rates of magma transport, storage, and crystallization, as well as to quantitatively determine elastic and inelastic deformation and the build up and decay of stress within the active volcanic system. Discussion of these topics is keyed to an annotated bibliography from which quantitative information on properties and processes may be obtained. Emphasis is on Hawaii's active basaltic volcanoes for which the most information is available. Additional references are made to research at Mount St. Helens, one of the first real-time studies of an active volcano of dacitic composition.

Hawaii, Washington↗