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At least 595 records · Page 33Linked to original sources
USGS1995

Relation of fracture orientation to linear terrain features, anisotropic transmissivity, and seepage to streams in the karst Prairie du Chien Group, southeastern Minnesota

Ground-water flow in the karst-terrane aquifers of southeastern Minnesota is not well defined. Variable fracture patterns in the bedrock affect permeability. Techniques to predict the effects of fracture patterns on ground-water flow in the karst-terrane aquifers of southeastern Minnesota are unavailable. The use of such techniques may be useful to officials responsible for the management and protection of ground water in these aquifers, which have a high susceptibility to contamination. The U.S. Geological Survey, in cooperation with the Minnesota Department of Natural Resources and the Legislative Commission on Minnesota Resources, investigated fracture patterns, anisotropic transmissivity, and seepage to streams from the Prairie du Chien Group, which is the karst portion of the St. Peter-Prairie du Chien-Jordan aquifer, to improve the understanding of ground-water flow through karst-terrane aquifers in southeastern Minnesota. This report presents the results of testing hypotheses that (1) the major axes of linear terrain features correlate with the major axes of subsurface fractures in the Prairie du Chien Group, and that (2) the major axes of subsurface fractures in the Prairie du Chien Group correlate with seepage from the Prairie du Chien Group. The first hypothesis was tested by comparison of linear terrain features to fracture orientation measurements. Fracture orientations in 10 exposures of the Prairie du Chien Group at quarries, road cuts, and natural outcrops showed statistically significant directional trends at 8 of 10 sites. Directional trends of linear terrain features identified from 1:80,000 aerial photographs were significant in four of the ten 60-square mile areas that surround these sites. The fracture orientation measurements correlate with the local linear terrain features in 2 of the 10 sites. The second hypothesis was tested by analyzing the correlation between seepage rates into streams hydraulically connected to the Prairie du Chien Group and surrounding linear terrain features that were mapped in approximately 300 square mile areas. Data from Riceford Creek support this hypothesis; data from Crow Creek and Middle Fork of the Whitewater River and from Duschee Creek are inconclusive. This hypothesis could not be tested by the data from the Middle Fork of the Zumbro River, the South Branch of the Root River, and the South Branch of the Middle Fork of the Zumbro River because the surrounding linear terrain features lack directional trends. The transmissivity of the karst portion of the St. Peter-Prairie du Chien-Jordan aquifer is anisotropic at an aquifertest site in the study area. Results of the aquifer test indicate that the major axis of transmissivity is along a line N95°E. The aquifer-test results indicate that the principal axis of joint fractures at the test site is slightly clockwise from an east-west line because this axis is assumed to correlate with the major axis of horizontal transmissivity.

Minnesota↗
USGS1995

Uraniferous waters of the Arkansas River valley, Colorado, U.S.A.: A function of geology and land use

The effect of local geology and land-use practices on dissolved U was investigated by analysis of surface water and some springs in the Arkansas River valley of southeastern Colorado. Water samples were collected during a 2 week period in April, 1991. The rate of increase of U concentration with distance downriver increased markedly as the river flowed from predominantly undeveloped lands underlain by igneous and metamorphic rocks to agriculturally developed lands underlain by marine shale and limestone. An additional abrupt increase in dissolved U was observed along the section of river where discharge is often greatly reduced because of extensive diversions for irrigation and where remaining flow is largely composed of irrigation return water. Dissolved U in this last section of river and in most of its tributaries exceeded the proposed U.S. drinking water standard of 20 μ/L In water samples collected from agricultural areas dissolved U showed strong positive correlation with major dissolved constituents Na, Ca, Mg, and SO 4 that increase as a result of sulfate mineral dissolution and clay mineral ion-exchange reactions in weathered shale bedrock and shaley soils. Highly soluble minor and trace elements Cl, Li, B, Sr, and Se that are not subject to strong sorptive uptake or precipitation in this setting also correlated positively with U. These combined observations indicate that natural leaching of U-bearing shale bedrock and derivative soils, additional leaching of rock and soil by irrigation water, and evaporative concentration in a semi-arid climate can produce concentrations of dissolved U in surface water and shallow ground water that may threaten nearby drinking water supplies. Other agriculturally developed areas of the semi-arid Western U.S. with similar geology are likely to contain high concentrations of U in irrigation drain water.

Colorado↗
USGS2006

Test hold in aquifer with many water-bearing zones at Jacksonville, Florida

One of the deepest water ‐exploration wells in the southeastern United States was completed in 1966 at Jacksonville , Florida . It was drilled to a depth of nearly 2,500 feet to supply geologic and hydrologic information on the deeper unexplored part of the Floridan aquifer . This aquifer consists of a series of water producing zones separated by nonproducing zones . An important new fresh‐ water producing zone was found, and the contact between the fresh water and salt water was located. The well was completed in three separate zones so that it could be used to monitor the the deeper part of the aquifer to detect any salt‐ water encroachment. This paper describes the objectives, techniques, and results of drilling the test well.

Florida↗
USGS2019

Discovering blind geothermal systems in the Great Basin Region: An integrated geologic and geophysical approach for establishing geothermal play fairways: All phases

Most geothermal resources in the Great Basin region of the western USA are blind, and thus the discovery of new commercial-grade systems requires synthesis of favorable characteristics for geothermal activity. The geothermal play fairway concept involves integration of multiple parameters indicative of geothermal activity to identify promising areas for new development. This project integrated multiple datasets to apply the play fairway concept and assess geothermal potential in a large region of the Great Basin in Nevada. It is therefore referred to as the Nevada play fairway project. This project was a strong collaborative effort between several organizations, led by the Nevada Bureau of Mines and Geology at the University of Nevada, Reno, but with key support from the U.S. Geological Survey, ATLAS Geosciences, Inc,, Hi-Q Geophysical, Inc., Lawrence Berkeley National Laboratory, Utah Geological Survey, and Innovative Geothermal Ltd. In Budget Period 1 of this project, available data for nine geologic, geochemical, and geophysical parameters were initially synthesized to produce a new detailed geothermal potential map of 96,000 km2 from west-central to eastern Nevada (Figure 1). These parameters were grouped into subsets and individually weighted (Figure 2) to delineate rankings for local permeability, intermediate permeability, regional permeability, and thermal potential, which collectively defined geothermal play fairways (i.e., most likely locations for significant geothermal fluid flow). This initial work was aimed at reducing the risks in regional exploration and therefore facilitating discovery of new commercial-grade systems in blind settings, as well as in areas with surface expressions of geothermal activity. Budget Period 2 of the project involved detailed analysis of some of the most promising areas identified in Phase 1. Twenty-four highly prospective areas, including both known undeveloped systems and previously undiscovered potential blind systems, were identified for further analysis (Figures 3 and 4). After reconnaissance of these areas, five of the most promising sites were selected for detailed studies. Multiple techniques were employed in the detailed studies, including geologic mapping, shallow temperature surveys, gravity surveys, Lidar, geochemical studies, seismic reflection analysis, and 3D modeling. The goal of the detailed studies was to identify specific areas with the highest likelihood for high permeability and thermal fluids, such that drill sites could be targeted. Three main sets of predictive maps were generated for each detailed study area: 1) play fairway maps, 2) play fairway error maps, and 3) direct evidence maps. Local- and intermediate-scale permeability models were revised to reflect results of the detailed geologic, geophysical, and geochemical analyses. Budget Period 3 of the project involved more detailed geophysical analyses and temperature-gradient (TG) drilling in southeastern Gabbs Valley and northern Granite Springs Valley (Figure 4), deemed the two most promising sites, with the goal of providing preliminary validation of the play fairway methodology. In southeastern Gabbs Valley, the collocation of a favorable structural setting (displacement transfer zone and fault intersections), Quaternary faults, intersecting and terminating gravity gradients, magnetic low, shallow (2 m) temperature anomaly, low resistivity anomaly, and promising geothermometry from nearby water wells provided evidence for a blind system. Drilling of six TG holes defines an apparent geothermal system at this locality with temperatures as high as 124°C at 152 m. This system is blind, with no surface hot springs, fumaroles, or paleo-geothermal deposits. For northern Granite Springs Valley, a favorable structural setting (termination of a major Quaternary normal fault), terminating gravity gradient, magnetic gradient, newly discovered sinter deposits, nearby warm water wells, previously drilled TG holes in the vicinity, and promising geothermometry suggest a hidden system. Drilling of six new TG holes yields temperatures of ~96°C at ~250 m, suggesting the presence of a geothermal system. Major lessons learned in the course of this project include: 1) initially identified sites commonly include multiple favorable structural settings at a finer scale; 2) promising sites in Cenozoic basins cannot be recognized without detailed geophysical surveys; and 3) play fairway analysis should be refined as the exploration program vectors into the most promising sites and finer-scale data are acquired. In addition to producing copious amounts of data, this project resulted in 16 published papers, 10 abstracts, more than 40 presentations across the U.S. and abroad (including several keynote addresses), 2 Masters theses, and 7 media reports.

Nevada↗
USGS2014

The Southeast Stream Quality Assessment

In 2014, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) is assessing stream quality across the Piedmont and southern Appalachian Mountains in the southeastern United States. The goal of the Southeast Stream Quality Assessment (SESQA) is to characterize multiple water-quality factors that are stressors to aquatic life—contaminants, nutrients, sediment, and streamflow alteration—and the relation of these stressors to ecological conditions in streams throughout the region. Findings will provide communities and policymakers with information on which human and environmental factors are the most critical in controlling stream quality and, thus, provide insights about possible approaches to protect or improve stream quality. The SESQA study will be the second regional study by the NAWQA program, and it will be of similar design and scope as the Midwest Stream Quality Assessment conducted in 2013 (Van Metre and others, 2012).

Alabama, Georgia, Kentucky, North Carolina, Pennsy↗
USGS2015

Design and methods of the Southeast Stream Quality Assessment (SESQA), 2014

During 2014, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) assessed stream quality across the Piedmont and southern Appalachian Mountain regions of the southeastern United States. This Southeast Stream Quality Assessment (SESQA) simultaneously characterized watershed and stream-reach water-quality stressors along with instream biological conditions, in order to better understand regional stressor-effects relations. The goal of SESQA is to provide communities and policymakers with information about those human and environmental factors that have the greatest impact on stream quality across the region. The SESQA design focused on hydrologic alteration and urbanization because of their importance as ecological stressors of particular concern to Southeast region resource managers. Streamflow and land-use data were used to identify and select sites representing gradients in urbanization and streamflow alteration across the region. One hundred fifteen sites were selected and sampled for as many as 10 weeks during April, May, and June 2014 for contaminants, nutrients, and sediment. This water-quality “index” period culminated with an ecological survey of habitat, periphyton, benthic macroinvertebrates, and fish at all sites. Sediment was collected during the ecological survey for analysis of sediment chemistry and toxicity testing. Of the 115 sites, 59 were on streams in watersheds with varying degrees of urban land use, 5 were on streams with multiple confined animal feeding operations, and 13 were reference sites with little or no development in their watersheds. The remaining 38 “hydro” sites were on streams in watersheds with relatively little agricultural or urban development but with hydrologic alteration, such as a dam or reservoir. This report provides a detailed description of the SESQA study components, including surveys of ecological conditions, routine water sampling, deployment of passive polar organic compound integrative samplers for pesticides and contaminants of emerging concern, and synoptic sediment sampling and toxicity testing at all urban, confined animal feeding operation, and reference sites. Continuous water-quality monitoring and daily pesticide sampling efforts conducted at a subset of urban sites are also described.

Alabama, Georgia, North Carolina, South Carolina, ↗
USGS2021

Stratigraphic cross sections of the Mowry Shale and associated strata in the Wind River Basin, Wyoming

The Wind River Basin in Wyoming is one of many structural and sedimentary basins that formed in the Rocky Mountain foreland during the Laramide orogeny in the latest Cretaceous through the early Eocene. The basin (bounded by the Washakie, Owl Creek, and Bighorn uplifts on the north, the Casper arch on the east, the Granite Mountains uplift on the south, and Wind River uplift on the west) encompasses about 7,400 square miles in central Wyoming. The two stratigraphic cross sections presented in this report were constructed as part of a project carried out by the U.S. Geological Survey to characterize and evaluate the undiscovered continuous (unconventional) oil and gas resources of the Mowry Shale in the Wind River Basin in central Wyoming. The purpose of the cross sections is to show the stratigraphic relationship of the Mowry Shale and associated Lower and lowermost Upper Cretaceous strata in the Wind River Basin. These two cross sections were constructed using borehole geophysical logs from 41 wells drilled for oil and gas exploration and production, and one research well that was cored and logged by the U.S. Geological Survey. Both lines originate at Sheldon Dome in the northwestern part of the basin and end near Bates Creek in the extreme southeastern part of the basin. The stratigraphic interval extends from the uppermost part of the Upper Jurassic Morrison Formation to the basal part of the Upper Cretaceous Frontier Formation. The datum is the top of the Clay Spur Bentonite Bed, a distinctive bed at the top of the Upper Cretaceous Mowry Shale. A gamma ray and (or) spontaneous potential log was used in combination with a resistivity log to identify and correlate units.

Wyoming↗
USGS1987

Maps showing distribution of the Middle Cretaceous unconformity in the eastern Gulf of Mexico

Several theories on the origin of the Gulf of Mexico basin have been introduced by various researchers (Beloussov, 1970; Freeland and Dietz, 1971; Malfait and Dinkelman, 1972; Wood and Walper, 1974; Pilger, 1978; Buffler and others, 1980; Dickinson and Coney, 1980; Gose and others, 1980; Schmidt-Effing, 1980; Walper, 1980; Schlager and others, 1984). Although no final agreement has been reached, one prominent geologic feature is generally recognized. The early evolution of the basin ended with a major middle Cretaceous event resulting in a Gulf-wide unconformity referred to as the middle Cretaceous unconformity (MCU). This event represents a major shift from Early Cretaceous shallow-water bank sedimentation to Late Cretaceous deeper water carbonates (Worzel and others, 1973; Mitchum, 1978). Seismic data collected by the U.S. Geological Survey and the University of Texas Marine Science Institute, Galveston Geophysics Laboratory (UTMSI-GGL) were used to map the MCU and its relationship to the deep stratigraphy and structure of the eastern Gulf basin east of long 90° W. In addition, data from the Deep Sea Drilling Project (DSDP) in the southeastern Gulf and along the Campeche Escarpment and dredge samples collected by Schlager and others (1984) from the Florida Escarpment provide an age for the MCU (Cenomanian, 97 m. y. ) and a detailed lithological record. This report emphasizes the salt diapirs, pillows, and ridges in the northeastern Gulf of Mexico because of the profound effect these geologic structures have on the MCU. Salt locations are shown on the isopach of post-MCU sediments (fig. 1). A second map shows pre-middle Cretaceous outcrops terminated by the MCU along the Florida Escarpment, the southeastern Gulf, and the Campeche Escarpment (fig. 2).

Miscellaneous Field Studies Map↗
USGS1978

Reconnaissance geology and geochronology of the Precambrian of the Granite Mountains, Wyoming

The Precambrian of the western part of the Granite Mountains, Wyoming, contains a metamorphic complex of gneisses, schists, and amphibolites that were derived through amphibolite-grade metamorphism from a sedimentary-volcanic sequence perhaps similar to that exposed in the southeastern Wind River Mountains. Whole-rock Rb-Sr dating places the time of metamorphism at 2,860?80 million years. A high initial 87Sr/ 86 S r ratio of 0.7048 suggests that either the protoliths or the source terrane of the sedimentary component is several hundred million years older than the time of metamorphism. Following an interval of 300:t100 million years for which the geologic record is lacking or still undeciphered, the metamorphic complex was intruded by a batholith and satellite bodies of medium- to coarse-grained, generally massive biotite granite and related pegmatite and aplite. The main body of granite is dated at 2,550?60 million years by the Rb-Sr method. Limited data suggest that diabase dikes were emplaced and nephrite veins were formed only shortly after intrusion of the granite. Emplacement of the granite at about 2,550 million years ago appears to be related to a major period of regional granitic plutonism in the Precambrian of southern and western Wyoming. Granites, in the strict sense, that are dated between 2,450 and 2,600 million years occur in the Teton Range, the Sierra Madre, the Medicine Bow Mountains and the Laramie Range. This episode of granitic plutonism occurred some 50 to 100 million years later than the major tonalitic to granitic plutonism in the Superior province of northern Minnesota and adjacent Ontario-the nearest exposed Precambrian W terrane that is analogous to the Wyoming province. Initial 87Sr / 86Sr ratios of some of the Wyoming granites are higher than expected if the rocks had been derived from juvenile magmas and it is likely that older crustal rocks were involved to some degree in the generation of these granites. Slightly to highly disturbed Rb-Sr and K-Ar mineral ages are obtained on rocks of the metamorphic complex and on the granite. These ages range from about 2,400 to 1,420 million years and are part of a regional pattern of lowered mineral ages of Precambrian W rocks of southern Wyoming. A major discontinuity in these mineral ages occurs along a line extending from the northern Laramie Range, through the northern part of the Granite Mountains, to the southeastern Wind River Mountains. North of this line, Rb-Sr and K-Ar biotite ages are 2,300 million years or greater, whereas to the south, the biotite ages decrease drastically over a short distance, to a common range of 1,600-1,400 million years. We suggest that these lowered ages represent regional cooling below the 300 0 C isotherm as a consequence of uplift and erosion of the large crustal block occurring south of the age discontinuity. In this interpretation, the westerly-trending age discontinuity would be a zone of major crustal dislocation that resulted from vertical tectonics in late Precambrian X or early Precambrian Y time.

Professional Paper↗
USGS2015

Mineral potential for sediment-hosted copper deposits in the Islamic Republic of Mauritania (phase V, deliverable 75)

The presence of Neoproterozoic through Cambrian, continental, siliciclastic sedimentary rocks interbedded with dolomitic carbonates, shales, and glacial tillites similar to the Katanga Supergroup host rocks of the Central African Copperbelt and other sediment-hosted copper-bearing Proterozoic sequences worldwide, is first order criteria for consideration of the Neoproterozoic units of the Taoudeni Basin in Mauritania as prospective for sediment-hosted copper deposits. Review of the National Mineral Occurrences Database (Marsh and Anderson, 2015) and previous literature suggest that only a handful of small sediment-hosted copper occurrences have been found to date in Mauritania and that the resource potential for this deposit type is low. In the northern Taoudeni Basin, the most important occurrence is at Taradent. This occurrence consists of three mineralized horizons in the lower Neoproterozoic Char Group in three outcrop areas separated by alluvium over a strike length of 12 kilometers (km). The most extensively mineralized horizon consists of malachite and disseminated copper sulfides, and is concentrated at the base of a dolomitic interval, consistent with a reduced faciestype sediment-hosted copper deposit model. Additional and poorly described copper occurrences in the Taoudeni Basin margin sedimentary rocks in northeastern Mauritania, such as Chegga Guettatira and Sidi Bara, may be sediment-hosted copper occurrences and extend the potential throughout this portion of the Basin. Additional potential for sediment-hosted copper deposits is indicated in reports by the British Geological Survey (BGS; Gunn and others, 2004) and BRGM (Salpeteur, 2005) in the Neoproterozoic-Cambrian sedimentary rocks (Teniagouri Group) of the central and southern Taoudeni Basin at a number of occurrences in the vicinity of Fouges, Weringuel, and Gig Zig. These occurrences exhibit characteristics consistent with a reduced-facies-type sediment-hosted copper deposit model and based on correlation of similar host rocks extend the potential throughout the entire Taoudeni Basin margin. Very poorly described copper occurrences in the northeastern and southeastern part of the Basin at Kreb en Naga, Kreb en Naga SW, Berbere, Dhar Nema, Dhar Nema 2, Saile, and Nejam-Medroume all are described as occurring in sedimentary rocks and are hosted by or are in close proximity to voluminous outcrops of Jurassic microgabbros (also referred to as dolerite or diabase). Uncertainty exists as to whether they are sediment-hosted copper occurrences. They are likely more closely analogous to copper occurrences associated with mafic igneous activity. The determination of whether reported copper occurrences and associated sedimentary rocks at Kreb en Naga and Kreb en Naga SW in the northeastern Taoudeni Basin and the Dhar Nema occurrences in the southeastern Taoudeni are permissive of sediment-hosted copper mineralization was inconclusive due to the absence of copper showings. While sedimentary host rocks at these locations must be broadly considered permissive, the absence of other favorable geologic features in these areas indicates that the potential for mineral deposits of this type is low. The widespread presence of mafic sills and dikes of Jurassic age throughout these areas and descriptions of associated minor copper mineralization suggests that many of the copper occurrences in these areas are not of the sediment-hosted copper type. Highly speculative potential exists in the Coastal Basin for Revett-type copper deposits in unexposed Jurassic-Cretaceous sandstones that may contain structural traps with gas accumulations. Eocene continental red bed sandstones of the Gorgol Formation, where overlain by the shallow marine sedimentary rocks of the Rinndiao Formation, represent an additional low potential rock sequence within the southeastern portion of the Coastal Basin that is permissive of sediment-hosted copper deposits. Field examinations of outcrop areas in the vicinity of many of the known occurrences were performed in late 2007 to provide additional criteria for evaluating the potential for this type of mineralization in Mauritania. In general, the geographic coordinates of occurrences are imprecise and many of the occurrences could not be located. Examination of outcrops of the Char Group in the Taradent area confirms the permissive nature of these rocks for reduced-facies-type sediment-hosted copper deposits. Inspection of weak copper mineralization hosted by black shales at several occurrences in the Gadel-Maylime area confirms that these occurrences are also of the reduced-faciestype and that the black and green shales of the Bouly and Ould Yenje Formations are permissive. Reported copper analyses up to 0.75 percent copper at Taradent and a single analysis of mineralized shale in the Gadel-Maylime area containing 0.55 percent copper indicate that low grade ore material exists at these locations. However indications that such copper grades are continuous over significant intervals and present in large tonnages are lacking. Although mineral occurrence data and descriptive geological information are adequate to delineate areas favorable for sediment-hosted copper deposits, this review indicates that potential for this type of deposit in Mauritania is low.

Open-File Report↗
USGS1996

Geologic map of the Silver Bell and West Silver Bell mountains, southern Arizona

The Silver Bell Mountains, 50 km northwest of Tucson, Arizona, are a mountain range in the transition from the higher-relief mountains of southeastern Arizona to the low-relief ranges of the western Arizona deserts. The Silver Bell Mountains include the area of the Silver Bell mining district (Richard and Courtright, 1966) which has produced over 100 million pounds of copper (Graybeal, 1982) since mining began in the late 19th century. Most of the mountain range and adjoining flanks are composed of Upper Cretaceous volcanic and plutonic rocks which are interpreted as parts of a ash-flow caldera; the intrusions which formed the porphyry copper deposits of the Silver Bell mining district were emplaced into the caldera margin. The latest Cretaceous and early Tertiary period of formation of most of Arizona's many copper deposits during was also a period of widespread continental silicic caldera volcanism, later fragmented into alternating mountain range exposures and buried beneath alluvial basins by late Tertiary extensional deformation. Lipman and Sawyer (1985) identified as many as seven Cretaceous caldera fragments in southern Arizona, as well as pieces of Cretaceous volcanoes in more than a half-dozen other mountain ranges in southern Arizona. Undoubtedly, much of the evidence about the character of Cretaeous volcanism is buried beneath alluvial valleys. This is the fourth detailed mapping study of these Cretaceous volcanoes: studies of the Tombstone caldera (Moore, 1994) and the Tucson Mountain caldera (Lipman, 1994) have recently been published, and a geologic map of Cretaceous volcanic rocks in the Sierrita Mountains (Fridrich and Lipman, 1991) is in preparation.

Arizona↗
USGS2007

Geologic Map of the Frederick 30' x 60' Quadrangle, Maryland, Virginia, and West Virginia

The Frederick 30? ? 60? quadrangle lies within the Potomac River watershed of the Chesapeake Bay drainage basin. The map area covers parts of Montgomery, Howard, Carroll, Frederick, and Washington Counties in Maryland; Loudoun, Clarke, and Fairfax Counties in Virginia; and Jefferson and Berkeley Counties in West Virginia. Many geologic features (such as faults and folds) are named for geographic features that may or may not be shown on the 1:100,000-scale base map. The geology of the Frederick 30? ? 60? quadrangle, Maryland, Virginia, and West Virginia, was first mapped on the 32 1:24,000-scale 7.5-minute quadrangle base maps between 1989 and 1994. The geologic data were compiled manually at 1:100,000 scale in 1997 and were digitized between 1998 and 1999. The geologic map and database may be used to support activities such as land-use planning, soil mapping, groundwater availability and quality studies, identifying aggregate resources, and conducting engineering and environmental studies. The map area covers distinct geologic provinces and sections of the central Appalachian region that are defined by unique bedrock and resulting landforms. From west to east, the provinces include the Great Valley section of the Valley and Ridge province, the Blue Ridge province, and the Piedmont province; in the extreme southeastern corner, a small part of the Coastal Plain province is present. The Piedmont province is divided into several sections; from west to east, hey are the Frederick Valley synclinorium, the Culpeper and Gettysburg basins, the Sugarloaf Mountain anticlinorium, the Westminster terrane, and the Potomac terrane. The geology of the Frederick quadrangle is discussed by geologic province and sections; the geologic units within each province are discussed from oldest to youngest. Where applicable, the discussion includes information on tectonic origins. For more information concerning the report, please contact the author.

Scientific Investigations Map↗
USGS1978

Landsat investigations of the northern Paradox basin, Utah and Colorado: Implications for radioactive waste emplacement Part 1. Lineaments and alignments

The first stages of a remote-sensing project on the Paradox basin, part of the USGS (U.S. Geological Survey) radioactive waste-emplacement program, consisted of a review and selection of the best available satellite scanner images to use in geomorphologic and tectonic investigations of the region. High-quality Landsat images in several spectral bands (E-2260-17124 and E-5165-17030), taken under low sun angle October 9 and 10, 1975, were processed via computer for planimetric rectification, histogram analysis, linear transformation of radiance values, and edge enhancement. A lineament map of the northern Paradox basin was subsequently compiled at 1:400,000 using the enhanced Landsat base. Numerous previously unmapped northeast-trending lineaments between the Green River and Yellowcat dome; confirmatory detail on the structural control of major segments of the Colorado, Gunnison, and Dolores Rivers; and new evidence for late Phanerozoic reactivation of Precambrian basement structures are among the new contributions to the tectonics of the region. Lineament trends appear to be compatible with the postulated Colorado lineament zone, with geophysical potential-field anomalies, and with a northeast-trending basement fault pattern. Combined Landsat, geologic, and geophysical field evidence for this interpretation includes the sinuousity of the composite Salt Valley anticline, the transection of the Moab-Spanish Valley anticline on its southeastern end by northeast-striking faults, and possible transection (?) of the Moab diapir. Similarly, northeast-trending lineaments in Cottonwood Canyon and elsewhere are interpreted as manifestations of structures associated with northeasterly trends in the magnetic and gravity fields of the La Sal Mountains region. Other long northwesterly lineaments near the western termination of the Ryan Creek fault zone. may be associated with the fault zone separating the Uncompahgre horst uplift from the Paradox basin. Implications of the present investigation for a potential radioactive waste-emplacement site in Salt Valley include confirmation of lack of permanent surface drainage and absence of agricultural or other development in the area of northern Salt Valley. On the other hand, the existence of diapirism, salt-karst landforms, and extensive lineamentation of the northern Paradox basin suggest regional tectonic instability at least in the geologic past. Future reactivation of diapiric or other halokinetic processes, including lateral flow, would lead to plastic behavior of the halite that might cause emplaced waste containers to migrate within the diapir. At Salt Valley, existing diapiric boundary faults and intersecting joint sets in sandstone units on the anticlinal flanks could, if the hydraulic gradient is suitable, provide conduits to the halite core for circulating ground water from adjacent Mesozoic sandstones in synclinal areas between the salt diapirs. Moreover, the loci of major lineament intersections might be areas of somewhat elevated seismic risk. If the salt barrier of Salt Valley anticline should fail in the future, potentially water-bearing Mesozoic fissile shales and friable to quartizitic sandstones would be the ultimate repository of the emplaced radioactive waste.

Colorado, Utah↗
USGS1981

Geologic map of the Beaver Creek Wilderness, McCreary County, Kentucky

The Beaver Creek Wilderness comprises approximately 4,800 acres and is principally within the cliffline bordering the Beaver Creek drainage basin in McCreary County, southeastern Kentucky. It is part of the Beaver Creek Cooperative Wildlife management Area in the Daniel Boone National Forest, which is managed by the U.S. Forest Service and the Kentucky Department of Fish and Wildlife Resources. The wilderness is about 11 mi southeast of Burnside, Ky., and is accessible from thr north and south via U.S. Route 27 and Forest Service Road 50, at its northwest border (fig. 1). From the east the area can be reached via State Route 90 and Forest Service Road 46, at the eastern end of the wilderness. The interiors is accessible by foot along an abandoned Forest Service road and by several primitive trails that extend along the major streams. The Beaver Creek Wilderness is centrally located at the western edge of the Appalachian coal regions and is within the highly dissected Cumberland Plateau section of the Appalachian Plateaus physiographic province (fig. 2). It is drained by Beaver Creek and tributaries, which flow northeastward into Cumberland Lake, a reservoir on the Cumberland River about 1 mi north of the wilderness. Altitudes range from about 730 ft on the lower part of Beaver Creek to about 1,200 ft at its headwaters.

Kentucky↗
USGS2007

Geologic Map of the Warm Spring Canyon Area, Death Valley National Park, Inyo County, California, With a Discussion of the Regional Significance of the Stratigraphy and Structure

Warm Spring Canyon is located in the southeastern part of the Panamint Range in east-central California, 54 km south of Death Valley National Park headquarters at Furnace Creek Ranch. For the relatively small size of the area mapped (57 km2), an unusual variety of Proterozoic and Phanerozoic rocks is present. The outcrop distribution of these rocks largely resulted from movement on the east-west-striking, south-directed Butte Valley Thrust Fault of Jurassic age. The upper plate of the thrust fault comprises a basement of Paleoproterozoic schist and gneiss overlain by a thick sequence of Mesoproterozoic and Neoproterozoic rocks, the latter of which includes diamictite generally considered to be of glacial origin. The lower plate is composed of Devonian to Permian marine formations overlain by Jurassic volcanic and sedimentary rocks. Late Jurassic or Early Cretaceous plutons intrude rocks of the area, and one pluton intrudes the Butte Valley Thrust Fault. Low-angle detachment faults of presumed Tertiary age underlie large masses of Neoproterozoic dolomite in parts of the area. Movement on these faults predated emplacement of middle Miocene volcanic rocks in deep, east-striking paleovalleys. Excellent exposures of all the rocks and structural features in the area result from sparse vegetation in the dry desert climate and from deep erosion along Warm Spring Canyon and its tributaries.

Scientific Investigations Map↗
USGS1997

Probabilistic and statistical relationships between number of vehicles and number of visitors at a geologic site in a National Park

The National Park Service needs to establish in all of the national parks how large the parking lots should be in order to enjoy and presence our natural resources, for example, in the Delicate Arch in the Arches National Park. Probabilistic and statistical relationships were developed between the number of vehicles (N) at one time in the Wolfe Ranch parking lot and the number of visitors (X) at Delicate Arch 1.5 miles away in the Arches National Park, southeastern Utah. The value of N is determined such that 30 or more visitors are at the arch only 10% of the time.

Mathematical Geology↗
USGS2001

Effects of urbanization on streamflow in the Atlanta area (Georgia, USA): A comparative hydrological approach

For the period from 1958 to 1996, streamflow characteristics of a highly urbanized watershed were compared with less-urbanized and non-urbanized watersheds within a 20 000 km2 region in the vicinity of Atlanta, Georgia: In the Piedmont and Blue Ridge physiographic provinces of the southeastern USA. Water levels in several wells completed in surficial and crystalline-rock aquifers were also evaluated. Data were analysed for seven US Geological Survey (USGS) stream gauges, 17 National Weather Service rain gauges, and five USGS monitoring wells. Annual runoff coefficients (RCs; runoff as a fractional percentage of precipitation) for the urban stream (Peachtree Creek) were not significantly greater than for the less-urbanized watersheds. The RCs for some streams were similar to others and the similar streams were grouped according to location. The RCs decreased from the higher elevation and higher relief watersheds to the lower elevation and lower relief watersheds: Values were 0.54 for the two Blue Ridge streams. 0.37 for the four middle Piedmont streams (near Atlanta), and 0.28 for a southern Piedmont stream. For the 25 largest stormflows, the peak flows for Peachtree Creek were 30% to 100% greater then peak flows for the other stream. The storm recession period for the urban stream was 1-2 days less than that for the other streams and the recession was characterized by a 2-day storm recession constant that was, on average, 40 to 100% greater, i.e. streamflow decreased more rapidly than for the other streams. Baseflow recession constants ranged from 35 to 40% lower for Peachtree Creek than for the other streams; this is attributed to lower evapotranspiration losses, which result in a smaller change in groundwater storage than in the less-urbanized watersheds. Low flow of Peachtree Creek ranged from 25 to 35% less than the other streams, possibly the result of decreased infiltration caused by the more efficient routing of stormwater and the paving of groundwater rechange areas. The timing of daily or monthly groundwater-level fluctuations was similar annually in each well, reflecting the seasonal recharge. Although water-level monitoring only began in the 1980s for the two urban wells, water levels displayed a notable decline compared with non-urban wells since then; this is attributed to decreased groundwater rechange in the urban watersheds due to increased imperviousness and related rapid storm runoff. Copyright ?? 2001 John Wiley & Sons, Ltd.

Hydrological Processes↗
USGS1993

Intensity and duration of chemical weathering: An example from soil clays of the southeastern Koolau Mountains, Oahu, Hawaii

Orographic precipitation on the southern flank of the southeastern Koolau Mountains produces a pronounced precipitation gradient. The corresponding gradient in the intensity of the chemical weathering environment provides an opportunity to address the effects of varying chemical weathering intensity on the composition of clay-size weathering products in soils developed on basalt. In addition, little-modified remnants of the constructional surface of the Koolau Volcano, isolated by stream dissection, remain as facets on the southern ends of the parallel ridges of the study area. By comparing clay mineralogy of soils developed on these older geomorphic surfaces with those developed on the younger sharp-crested ridges and steep side slopes, the effects of weathering duration on clay mineralogy can also be addressed. Soil clays in this part of the Koolau Mountains are mineralogically complex; principal phases include smectite, kaolinite, and halloysite, but pure end member phases are uncommon. Rather, most phases contain some amount of mixed layering. Smectite may contain small (<5%) amounts of randomly interstratified halloysite. Similarly, kaolinite commonly contains a small proportion of halloysite interlayers. A complex halloysitic phase shows evidence of interstratification with both smectite and kaolinite. Nonphyllosilicates found in the clay fraction include gibbsite, goethite, rare quartz, and perhaps cristobalite. The gradient in precipitation is reflected in soil clay mineralogy by varying proportions of dominantly smectitic, kaolinitic, and halloysitic phases. In regions of relatively low precipitation (<2,000 mm/yr), soils are dominated by the smectitic and halloysitic phases. With increased precipitation (as much as ∼4,000 mm/yr), kaolinitic and halloysitic phases become the dominant clay minerals, and goethite and gibbsite become increasingly abundant. Older soils developed on geomorphic surfaces representing the original constructional surface of Koolau Volcano are markedly more leached than those from younger landscapes in the same precipitation regime. Although smectite may be present, kaolinite is the dominant phase, and accumulations of Fe and Ti occur in the uppermost soil levels. Enrichment of Zr and Ti in these soils, as compared to concentrations in the original basaltic parent material, indicates that as much as 75% of the parent material has been lost. Thus weathering duration may affect soil clay composition in the same way as weathering intensity. Because smectite and halloysite are expandable clay minerals, their presence in soils may decrease slope stability and influence the nature of slope processes. Soil avalanches occur on steep slopes throughout the study area, whereas slow-moving landslides appear to be restricted to gentler slopes in drier parts of the study area where smectite is abundant. The clay mineralogy of soils thus appears to influence the nature of slope processes in the southeastern Koolau Mountains.

Special Paper of the Geological Society of America↗