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At least 325 records · Page 18Linked to original sources

USGS1953

A magnetic investigation of the Round Mountain plug, Castle Valley, Grand County, Utah

A magnetic survey was made in Castle Valley, Grand County, Utah, to determine if the Round Mountain plug was fed laterally from the La Sal Mountains or vertically from a source at depth. Additional measurements were made around the exposure of igneous rock to obtain the shape of the plug at depth. No indication of a buried lateral igneous feeder was detected on the magnetic profileso The magnetic contour map showed that the plug was much larger than indicated by the diorite porphyry outcrop, and that the buried part of the plug southeast of Round Mountain has a higher magnetic susceptibility than the diorite outcrop. Theoretical anomalies, calculated using the susceptibility of the diorite outcrop, indicate that a lateral feeder at a depth of greater than 200 feet could not be detected. The size and shape of the magnetic anomaly as shown on the contour map suggest that the plug was fed from a source at depth.

Utah↗

USGS1954

Uranium in the Mayoworth area, Johnson County, Wyoming - a preliminary report

The uranium mineral, metatyuyamunite, occurs in the basal limestone of the Sundance formation of late Jurassic age along the east flank of the Bighorn Mountains, about 2 miles southwest of the abandoned Mayoworth post office. This occurrence is of particular interest because it is the first uranium mineralization reported from a marine limestone in Wyoming. The discovery uranium claims were filed in July 1953, by J.S. Masek, Dan Oglesby, and Jack Emery of Casper, Wyo. Subsequent reconnaissance investigations have been made by private individuals and geologists of the U.S. Geological Survey and Atomic Energy Commission. The metatyuyamunite is concentrated in a hard gray oolitic limestone that forms the basal bed of the Sundance formation. A selected sample of limestone from a fresh face in the northernmost deposit known at the time of the field examination contained 0.70 percent equivalent uranium and 0.71 percent uranium. Eight samples of the limestone taken at the sample place by the Atomic Energy Commission contained from 0.007 to 0.22 percent uranium. A chip sample from the weathered outcrop at the top of this limestone half a mile to the southeast contained 0.17 percent equivalent uranium and 0.030 percent uranium. A dinosaur bone from the middle part of the Morrison formation contained 0.044 percent equivalent uranium and 0.004 percent uranium. metatyuyamunite forms a conspicuous yellow coating along fracture planes cutting the oolitic limestone and has also replaced many of the oolites within the solid limestone and has also replaced many of the oolites within the solid limestone even where fractures are not present. Many radioactive spots in the basal limestone of the Sundance formation were examined in a reconnaissance fashion along the outcrop for a distance of half a mile south of the initial discovery. Samples were taken for analysis only at the northern and southern margins of this interval. Outcrops farther north and south were not studied. There are not sufficient data to make even rough estimates of tonnage and grade of the occurrences. The extent of the limestone, the approximate boundaries of the area of above-normal radioactivity, and the possibilities of other radioactive zones have not been thoroughly investigated. Although dinosaur bones in the Morrison formation were radioactive wherever they were tested, no significant amount of radioactivity was observed in rocks adjacent to the bones.

Wyoming↗

USGS2003

Ground-Water Resources in the Black Hills Area, South Dakota

The availability of ground-water resources in the Black Hills area is influenced by many factors including location, local recharge and ground-water flow conditions, and structural features. Thus, the availability of ground water can be extremely variable throughout the Black Hills area, and even when water is available, it may not be suitable for various uses depending on the water quality. The major bedrock aquifers in the Black Hills area are the Deadwood, Madison, Minnelusa, Minnekahta, and Inyan Kara aquifers. Minor bedrock aquifers occur in other hydrogeologic units, including confining units, due to fracturing and interbedded permeable layers. Various information and maps are presented in this report that describe availability and quality of ground-water resources in the Black Hills area. However, there is no guarantee of obtaining usable water at any location due to the extreme potential variability in conditions that can affect the availability and quality of ground water in the area. Maps presented in this report include the distribution of hydrogeologic units; depth to the top of the five formations that contain major aquifers; thickness of the five formations that contain major aquifers; potentiometric maps for the five major aquifers; saturated thickness of the Madison and Minnelusa aquifers; water temperature in the Madison aquifer; specific conductance in the Madison, Minnelusa, and Inyan Kara aquifers; hardness in the Inyan Kara aquifer; sulfate concentrations in the Minnelusa aquifer; and radon concentrations in the Deadwood aquifer. Water quality of the major aquifers generally is very good in and near outcrop areas but deteriorates progressively with distance from the outcrops. In the Minnelusa aquifer, an abrupt increase in concentrations of dissolved sulfate occurs downgradient from outcrop areas, where a zone of active anhydrite dissolution occurs. Most limitations for the use of ground water are related to aesthetic qualities associated with hardness and high concentrations of chloride, sulfate, sodium, manganese, and iron. Very few health-related limitations exist for ground water; most limitations are for radionuclides, such as radon and uranium. In addition, high concentrations of arsenic have been measured in a few samples from the Minnelusa aquifer.

Water-Resources Investigations Report↗

USGS2003

Vulnerability of ground water to contamination, northern Bexar County, Texas

The Trinity aquifer, composed of Lower Cretaceous carbonate rocks, largely controls the ground-water hydrology in the study area of northern Bexar County, Texas. Discharge from the Trinity aquifer recharges the downgradient, hydraulically connected Edwards aquifer one of the most permeable and productive aquifers in the Nation and the sole source of water for more than a million people in south-central Texas. The unconfined, karstic outcrop of the Edwards aquifer makes it particularly vulnerable to contamination resulting from urbanization that is spreading rapidly northward across an "environmentally sensitive" recharge zone of the Edwards aquifer and its upgradient "catchment area," composed mostly of the less permeable Trinity aquifer. A better understanding of the Trinity aquifer is needed to evaluate water-management decisions affecting the quality of water in both the Trinity and Edwards aquifers. A study was made, therefore, in cooperation with the San Antonio Water System to assess northern Bexar County's vulnerability to ground-water contamination. The vulnerability of ground water to contamination in this area varies with the effects of five categories of natural features (hydrogeologic units, faults, caves and (or) sinkholes, slopes, and soils) that occur on the outcrop and in the shallow subcrop of the Glen Rose Limestone. Where faults affect the rates of recharge or discharge or the patterns of ground-water flow in the Glen Rose Limestone, they likewise affect the risk of water-quality degradation. Caves and sinkholes generally increase the vulnerability of ground water to contamination, especially where their occurrences are concentrated. The slope of land surface can affect the vulnerability of ground water by controlling where and how long a potential contaminant remains on the surface. Disregarding the exception of steep slopes which are assumed to have no soil cover the greater the slope, the less the risk of ground-water contamination. Because most soils in the study area are uniformly thin, they have only minimal effect on the vulnerability of ground water to contamination. The results of hydrogeologic mapping during the present study divide the outcrop of the Glen Rose Limestone into five mappable intervals, labeled (youngest to oldest) A through E. Of these intervals, only the middle (C) and the lowermost (E) generally provide appreciable permeability. The vulnerability assessment provided herein was determined by combining the presumed effects of selected natural features (with individual vulnerability ratings ranging from 0 through 35) using a grid-based, multilayer system of digital datasets and geographic information system analysis. The resulting vulnerability map comprises composite vulnerability ratings that range from 26 through 104. The relatively less vulnerable areas those containing no faults, sinkholes, or caves occupy about 92 percent of the study area. The most vulnerable areas are those containing both a fault and one or more caves. The distribution of the most vulnerable areas which trend from southwest to northeast, roughly parallel to the Balcones fault zone occur mainly where faults intersect caves.

Texas↗

USGS1977

Water-level changes in wells along the west side of the Cedar Creek anticline, southeastern Montana

Water levels have been measured periodically in wells along the west side of the Cedar Creek anticline in southeastern Montana since 1962-64. The measurements show the response of the Fox Hills-Hell Creek aquifer of Late Cretaceous age to withdrawals for domestic, stock, and industrial uses. Water levels were as much as 109 feet lower in 1975 than they were in 1962-64. During the same period water levels lowered by 10 feet under about 400 square miles. From 1962-64 to 1969 water levels declined by as much as 133 feet. From 1969 to 1975 water levels rose as much as 46 feet near the outcrop of the aquifer and lowered 10 feet or more beneath about 100 square miles. Decreases in the rate of pumping from industrial wells near the outcrop have caused the water-level rise. Withdrawals from domestic and stock wells have remained the same or increased during the last 14 years and have contributed to water-level declines in areas west of the aquifer 's outcrop. (Woodard-USGS)

Montana↗

USGS1984

Depth and thickness of selected units in Upper Permian, Upper Jurassic, and Lower Cretaceous rocks in southwestern Kansas

As ground-water reserves decline in the Ogallala aquifer in an area of about 17,400 square miles in 26 counties of southwestern Kansas, sandstone aquifers in underlying Upper Jurassic and Lower and Upper Cretaceous rocks may be developed to supplement or replace the Ogallala as a source of water for some uses. Maps show that depths from land surface to Upper Permian rocks range from 0 at the outcrop to over 2,100 feet, depths to Upper Jurassic rocks ran from 0 at the outcrop to about 2,000 feet, depths to the Cheyenne Sandstone range from about 150 to about 1 ,950 feet, and depths to the Dakota Formation range from 0 at the outcrop to about 1,650 feet. Additional maps show that the thickness of Upper Jurassic rocks, where present, ranges from less than 50 feet to about 250 feet, the thickness of the Cheyenne Sandstone, where present, ranges from about 20 feet to about 250 feet, and the thickness of the Dakota Formation, where present, ranges from about 60 feet to about 460 feet. (USGS)

Water-Resources Investigations Report↗

USGS1986

Generalized potentiometric surface of the Catahoula aquifer in central Louisiana, 1980

Generalized contours of the altitude of water levels in wells completed in the Catahoula aquifer in central Louisiana, are illustrated by this map. Most water level measurements used in compiling the map were made in 1980; however, in parts of the State where water levels from 1980 were unavailable and where evidence indicated little change in water level, some measurements from as early as 1961 and as late as 1982 were used. Groundwater levels in and near the outcrop areas fluctuate 2 ft or less yearly and no significant long-term declines have occurred. The slow downward trend in water level altitude since early 1976 may be caused by pumpage from the Catahoula aquifer by a rural water system approximately 3 miles away. Recharge to the Catahoula aquifer occurs by rainfall on the upland outcrop-subcrop areas. Saltwater occurs throughout the Catahoula aquifer downgradient from the outcrop area. The ' approximate limit of freshwater ' line on the map indicates the downgradient limit of water with a concentration of chloride < 250 mg/L; the line was determined using water quality data and analysis of resistivity curves from geophysical well logs. Water from the Catahoula aquifer is used for municipal, industrial, and domestic purposes. Total pumpage from the aquifer in Louisiana was slightly over 1.1 million gallons/day in 1980. Local cones of depression result from pumpage just east of Anacoco in Vernon Parish and northwest of Jonesville in Catahoula Parish. (Lantz-PTT)

Louisiana↗

USGS1988

Geohydrology of the Navajo sandstone in western Kane, southwestern Garfield, and southeastern Iron counties, Utah

The upper Navajo and Lamb Point aquifers in the Navajo Sandstone are the principal source of water for the city of Kanab, irrigation, stock, and for rural homes in the study area. Well logs and outcrop descriptions indicate the Navajo Sandstone consists of the Lamb Point Tongue and an unnamed upper member that are separated by the Tenney Canyon Tongue of the Kayenta Formation. The main Kayenta Formation underlies the Lamb Point Tongue. The Lamb Point Tongue and the upper member of the Navajo Sandstone are saturated and hydraulically connected through the Tenney Canyon Tongue. Available data indicate that precipitation percolates to the groundwater reservoir where the Navajo Sandstone crops out. Estimates of the rate of recharge at the outcrop range from 0.1 to as much as 2.8 in/yr. Water level data indicate that water moves from the upper member of the Navajo Sandstone, through the Tenney Canyon Tongue, and into the Lamb Point Tongue. Lateral flow is generally from the outcrop areas toward the incised canyons formed by tributaries of Kanab Creek and Johnson Wash. Direction and rate of groundwater movement and the location and character of the natural hydrologic boundaries in the northern part of the area where the Navajo Sandstone is buried cannot be determined conclusively without additional water level data. (Author 's abstract)

Water-Resources Investigations Report↗

USGS1988

Reassessment of the Georgetown limestone as a hydrogeologic unit of the Edwards Aquifer, Georgetown area, Texas

The Edwards aquifer consists of geologic units known as the Comanche Peak (oldest) and Edwards Limestones, Kiamichi Formation, and Georgetown Limestone. The Edwards Limestone is the main water-bearing zone. The shallow geologic units dip to the east-southeast at a slope of 50 to 100 feet per mile in the Georgetown area. The Edwards aquifer extends from the western limits of the outcrop to the transition zone from freshwater to saline water to the east. The downdip continuity of the geologic units is interrupted by several faults in the Balcones fault zone. The aquifer is recharged by the infiltration of precipitation and streamflow in the outcrop and is discharged by springs in the outcrop and by wells, evapotranspiration, and leakage through the overlying confining bed in the confined area. Streams in the area regionally flow from the west to the east. A reassessment of the uppermost geologic unit of the Edwards aquifer, the Georgetown Limestone, was conducted in the Georgetown area, Texas, using: (1) data from six surveys of streamflow gains and losses and ground-water levels, (2) aquifer tests at three clusters of test wells, (3) variation in water-quality characteristics to indicate ground-water circulation, and (4) previous studies. Data from the six surveys did not show a pattern of corresponding streamflow gains and losses with positive (upward) and negative (downward) head differentials, respectively, between the main water-bearing zone of the Edwards aquifer and the streams. A consistent and corresponding pattern was shown only for the subreach containing Berry Springs. The aquifer tests consisted of "slug" test analyses to determine the transmissive characteristics of the Georgetown Limestone and produced 8 9 hydraulic conductivity values ranging from 1.4 X 10 -8 to 2.8 X 10 -9 centimeters per second at four of the six test wells. The other two test wells did not produce data suitable for conventional aquifer-test analysis. An analysis of the water-quality characteristics suggests that the Edwards Limestone and the streams have a significant hydraulic connection but the ground-water circulation between the Edwards Limestone and the Georgetown Limestone is very limited. The only area where a high degree of hydraulic connection between the main water-bearing zone of the Edwards aquifer (Edwards Limestone) and the streams was found is near the updip limits of the Georgetown Limestone, where a nearby major fault occurs and where major springs have developed. These findings suggest that the Georgetown Limestone does not function as a unit of the Edwards aquifer but as a regional confining bed with localized avenues that allow flow to and from the underlying Edwards aquifer.

Water-Resources Investigations Report↗

USGS1990

Altitude of potentiometric surface, fall 1985, and historic water-level changes in the Fort Pillow aquifer in western Tennessee

Recharge to the Fort Pillow aquifer of Tertiary age is from precipitation on the outcrop, which forms a narrow belt across western Tennessee, and by downward infiltration of water from the overlying fluvial deposits of Tertiary(?) and Quaternary age and alluvium of Quaternary age or, where the upper confining unit is absent, from the overlying Memphis aquifer of Tertiary age. The potentiometric surface in the Fort Pillow aquifer slopes gently westward from the outcrop-recharge area, and the water moves slowly in that direction. A depression in the potentiometric surface in the Memphis area is the result of past pumping at Memphis Light, Gas and Water Division well fields (1924-74), past and present pumping at an industrial well field at Memphis, and the municipal well field at West Memphis, Ark. Withdrawals from the Fort Pillow aquifer in western Tennessee in 1985 averaged about 12 million gallons per day. Water-level data from four observation wells, all in areas affected by pumping, indicate that water levels have declined at average rates ranging from about 0.4 to 0.9footperyearduring the past 40years (1945-85). The greatest rate of decline was as much as 4.0 feet per year between 1945 and 1954 in an observation well in a well field of Memphis Light, Gas and Water Division at Memphis. In 1971, Memphis Light, Gas and Water Division ceased pumping from the Fort Pillow aquifer at this well field, and between 1971 and 1976, water levels rose about 28 feet in this well. Water levels in the Fort Pillow aquifer in large areas of western Tennessee away from the effects of pumping have fluctuated only in response to long-term variations in precipitation on the outcrop-recharge belt. Long-term changes in water levels in these areas have been small.

Tennessee↗

USGS1995

Natural radioactivity in, and inorganic chemistry of, ground water in the Kirkwood-Cohansey aquifer system, southern New Jersey, 1983-89

The distribution of naturally occurring radionuclides in ground water of the Kirkwood- Cohansey aquifer system in southern New Jersey was assessed during 1988-89. The Kirkwood-Cohansey aquifer system consists of quartz-sand formations overlain by a feldspar-rich quartz-sand formation, the Bridgeton Formation, that is heavily developed agriculturally. The sum of the concentrations of radium-226 and radium-228 exceeded the U.S. Environmental Protection Agency maximum contaminant level (MCL) of 5 pCi/L (picocuries per liter) in 26 of 81 wells from which water samples were analyzed, and gross alpha-particle activity exceeded the MCL of 15 pCi/L in 5 of the 81 samples. The median concentrations of radon-222 and uranium were 280 pCi/L and 0.03 micrograms per liter, respectively. Water in the Kirkwood-Cohansey aquifer system generally is dilute (median dissolved solids concentration, 55 milligrams per liter) and acidic (median pH, 4.90), but concentrations of major ions and acidity are higher in water from wells in areas where the Bridgeton Formation outcrop and agricultural land use are present than in areas where they are absent. Concentrations and activities of radionuclides also were greatest in these areas. Results of statistical analyses indicate that these relations are significant and nonrandom. The positive relation of radionuclide concentration or activity to the presence of geologic outcrop and agricultural land, and a similar relation of the concentration of inorganic constituents to the presence of geologic outcrop and agricultural land, indicate that geochemical processes enhance mobilization of radionuclides in these areas relative to areas where the Bridgeton Formation and agricultural land are absent. The sum of the ccncentrations of radium-226 and radium-228 most likely exceeds the MCL in ground-water samples with nitrate concentrations greater than 5 milligrams per liter.

New Jersey↗

USGS1995

Geologic framework and hydrogeologic characteristics of the Edwards Aquifer recharge zone, Bexar County, Texas

In Bexar County, residential and commercial development on the Edwards aquifer recharge zone is increasing. The aquifer possibly can be contaminated by spills, leakage of hazardous materials, or runoff from the rapidly developing urban areas that surround, or are built on, the intensely faulted and fractured, karstic limestone outcrops characteristic of the recharge zone. Furthermore, some of the hydrogeologic subdivisions that compose the Edwards aquifer have greater effective porosity than others. The areas where the most porous subdivisions crop out might provide efficient avenues for contaminants to enter the aquifer. The Edwards aquifer recharge zone has relatively large permeability resulting, in part, from the development or redistribution of secondary porosity. Lithology, stratigraphy, diagenesis, and karstification account for the effective porosity and permeability in the Edwards aquifer outcrop. Karst features that greatly enhance effective porosity in the outcrop area include sinkholes and caves. Hydrogeologic subdivision VI, the Kirschberg evaporite member, appears to be the most porous and permeable subdivision within the Kainer Formation. Hydrogeologic subdivision HI, the leached and collapsed members, undivided, is the most porous and permeable subdivision within the Person Formation. Hydrogeologic subdivision II, the cyclic and marine members, undivided, is moderately permeable, with both fabric- and not-fabric-selective porosity. The faults in northern Bexar County are part of the Balcones fault zone. Although most of the faults in this area trend northeast, a smaller set of cross-faults trend northwest. Generally, the faults are en echelon and normal, with the downthrown blocks typically toward the coast.

Texas↗

USGS1998

Streamflow losses in the Black Hills of western South Dakota

Losses occur in numerous streams that cross outcrops of various sedimentary rocks that are exposed around the periphery of the Black Hills of South Dakota. These streamflow losses are recognized as an important source of local recharge to regional bedrock aquifers. Most streams lose all of their flow up to some threshold rate. Streamflow is maintained through a loss zone when the threshold is exceeded. Streamflow records for 86 measurement sites are used to determine bedrock loss thresholds for 24 area streams, which have individual loss thresholds that range from negligible (no loss) to as much as 50 cubic feet per second. In addition, insights are provided regarding springflow that occurs in the immediate vicinity of selected loss zones. Most losses occur to outcrops of the Madison Limestone and Minnelusa Formation. Losses to the Deadwood Formation probably are minimal. Losses to the Minnekahta Limestone generally are small; however, they are difficult to quantify because of potential losses to extensive alluvial deposits that commonly are located near Minnekahta outcrops. Loss thresholds for each stream are shown to be relatively constant, without measurable effects from streamflow rates or duration of flow through the loss zones. Calculated losses for measurements made during high-flow conditions generally have larger variability than calculated losses for low-flow conditions; however, consistent relations between losses and streamflow have not been identified. Some of this variability results from the inability to account for tributary inflows and changes in storage. Calculated losses are shown to decrease, in some cases, during periods of extended flow through loss zones. Decreased 'net' losses, however, generally can be attributed to springflow (ground-water discharge) within a loss zone, which may occur during prolonged periods of wet climatic conditions. Losses to unsaturated alluvial deposits located adjacent to the stream channels are found to have significant effects on determination of bedrock losses. Large losses occur in filling initial storage in unsaturated alluvial deposits downstream from loss zones, when bedrock loss thresholds are first exceeded. Losses to alluvial deposits in the range of tens of cubic feet per second and alluvial storage capacities in the range of hundreds of acre-feet are documented. Significant changes in loss thresholds for Grace Coolidge Creek, Spring Creek, and Whitewood Creek are documented. Introduction of large quantities of fine-grained sediments into these stream channels may have affected loss thresholds for various periods of time.

South Dakota↗

USGS1963

Geology and ground-water resources of Montgomery County, Alabama

Montgomery County includes an area of 790 square miles in east-central Alabama. The economy of Montgomery County is related primarily to the growing and processing of agricultural products. The county is in the northern part of the Coastal Plain. It consists of parts of four divisions of the Coastal Plain: the terraces, the Black Prairie, the Chunnennuggee Hills, and the flood plains. The county drains north and northwest into the Alabama and Tallapoosa Rivers, except for a small area in the southern part of the county that is drained by tributaries of the Conecuh River. Sedimentary rocks of Late Cretaceous age underlie Montgomery County. They are divided, in ascending order, into the following: Coker and Gordo formations of the Tuscaloosa group; Eutaw formation; and Mooreville and Demopolis chalks, Ripley formation, Prairie Bluff chalk, and Providence sand of the Selma group. The Clayton formation of Tertiary age crops out in a small area in the southern part of the county. Pleistocene terrace deposits of the ancestral Alabama River overlie the older rocks in the northern part of the county. Recent alluvium underlies the flood plains of the larger streams. The Cretaceous and younger rocks consist chiefly of clay, chalk, sandstone, sand, and gravel, and a few thin beds of limestone. These deposits are underlain by a basement complex of pre-Cretaceous crystalline rocks. Large-scale withdrawals of water began in the Montgomery area about 1885. Pumpage by the city of Montgomery in 1958 averaged about 15 million gallons per day. It is estimated that an additional 10 to 15 million gallons per day was pumped in the county for industrial, irrigation, domestic, and stock use. The principal aquifer in the country is the Eutaw formation. It supplies water to the city of Montgomery municipal wells, to industrial wells in the Montgomery area, and to most domestic and stock wells in the northern two-thirds of the county. Irrigation wells also tap the Eutaw. Yields from wells range from 350 to 600 gallons per minute. The Gordo formation, the upper part of the Coker formation, and the Pleistocene terrace deposits in the Montgomery area also yield moderate to large quantities of water to municipal and industrial wells. The lower part of the Coker formation is not developed as a source of water supply, but information obtained during the investigation rthat led to this report indicates that it may be a potential source of water to wells of large capacity. Sand beds in the Ripley formation, Providence sand, and Recent alluvium in -the southern part of the county yield adequate amounts of water to domestic and stock wells. Most of the ground water used in Montgomery County occurs under artesian conditions, although water-table conditions occur in the Pleistocene terrace deposits and Recent alluvium, and in the outcrop areas of the Eutaw and Eipley formations and the Providence sand. Most of the water recharging the Ooker, Gordo, and Eutaw formations in their areas of outcrop also is discharged in these areas; only a small quantity of water moves downdip beneath the overlying chalk beds. The natural discharge, and hence the natural recharge, is estimated to be 0.2 to 0.3 million gallons per day per square mile of outcrop. All ground water in the county is of chemical quality that is satisfactory for most uses, although locally it is high in iron or chloride content and is hard. Water from the Eutaw formation a few miles southwest of Montgomery's West well field is very high in chloride content. This water moves toward the cone of depression in the piezometric surface produced by pumping in the West well field. Much additional ground water could be pumped from the Eutaw formation, especially south of Montgomery's West well field. Additional water also is available from the upper part of the Coker formation. Before large groundwater developments are planned, however, the problems of well spacing and pumping rates should be studied in order to determine the maximum development permitted by the supply. Observation wells should be installed in the Eutaw formation southwest of Montgomery's West well field to detect encroachment of water of high chloride content from adjacent Lowndes County.

Alabama↗

USGS1968

Flow pattern and related chemical quality of ground water in the "500-foot" sand in the Memphis area, Tennessee

The '500-foot' sand is the major source of water supply for the Memphis area. Thick layers of impervious clay above and below the sand confine the water in the aquifer under artesian pressure and also protect the aquifer from contamination. Recharge from rainfall enters the '500-foot' sand in the outcrop, or intake area south and east of Memphis. Recharge from other aquifers enters the sand wherever the confining beds are breached or absent. Some of the recharge that enters the '500-foot' sand in eastern Arkansas moves down the gradients created by pumping in the Memphis area. All discharge from the '500-foot' sand in the Memphis area results from well pumping. Since 1886 continuous withdrawals at gradually increasing rates of pumping have lowered water levels and altered hydraulic gradients in the area. These withdrawals have resulted in changes in direction and velocity of movement of water through the '500-foot' sand. Water in the sand in the southeaster n part of the Memphis area normally moves from the (outcrop area east and south of Memphis northwestward toward points of withdrawal. In the northwestern part of the area, water moves southeastward toward points of withdrawal. A flow-net analysis of the aquifer shows that the rate of water movement through the '500-foot' sand in 1964, toward the major cones of depression in the Memphis area, was about 350 feet per year, or 1 mile in 15 years. A flow-net analysis projected for the year 1975 indicates the rate will increase by about 20 percent in the 12-year period 1964-75. Water in the '500-foot' sand in the Memphis area is generally a calcium magnesium sodium bicarbonate type. It is soft, low in dissolved solids, high in concentrations of iron and carbon dioxide, and slightly to moderately corrosive. The softest and least mineralized water occurs in the southeastern part of the area, and the water becomes slightly harder and more mineralized as it moves downdip toward Memphis. The hardest and most mineralized water occurs in the northwestern part of the area. The variations in chemical quality of water en route through the '500-foot' sand are virtually proportional to increases or decreases of the major chemical constituents. The variations are chiefly attributed to the mixing or blending of water from different directions or sources of recharge as wells are pumped. As water levels are lowered by continuous pumping in the future, increasing rates of recharge from the outcrop areas and from shallow aquifers will probably cause little, if any, change in chemical quality of the water. Certainly, the effects on quality are not expected to be detrimental. Although future changes in chemical quality of water in the '500-foot' sand in the Memphis area will probably be neither intense nor extensive, some changes can be anticipated as a result of man's activities associated with the continued growth and development of the area. Increased pumping at existing pumping centers will deepen existing cones of depression and thereby increase gradients. These increases will not necessarily cause a change in chemical quality unless the increases in pumping are unevenly distributed. If a major well field were developed in the '500-foot' sand in the southwestern part of the Memphis area, little change in quality would result because water would be caused to move toward the well field from both the northwest and southeast. This movement would not affect the blending of updip and downdip water at other well fields If water were impounded in the Wolf River a few miles upstream from Memphis, the impoundment could furnish recharge, at least temporarily, to the '500-foot' sand. It is improbable that any detrimental effects on the chemical quality of the water supply of Memphis would result, because the water in the impoundment would probably be softer ,and less mineralized than the water in the '500-foot' sand in that area.

Water Supply Paper↗

USGS1983

Hydrology of the Ferron Sandstone aquifer and effects of proposed surface-coal mining in Castle Valley, Utah, with a section on stratigraphy and a section on leaching of overburden

Coal in the Ferron Sandstone Member of the Mancos Shale of Cretaceous age has traditionally been mined by underground techniques in the Emery Coal Field in the southern end of Castle Valley in east-central Utah. However, approximately 99 million tons are recoverable by surface mining. Ground water in the Ferron is the sole source of supply for the town of Emery, but the aquifer is essentially untapped outside the Emery area. The Ferron Sandstone Member crops out along the eastern edge of Castle Valley and generally dips 2 ? to 10 ? to the northwest. Sandstones in the Ferron are enclosed between relatively impermeable shale in the Tununk and Blue Gate Members of the Mancos Shale. Along the outcrop, the Ferron ranges in thickness from about 80 feet in the northern part of Castle Valley to 850 feet in the southern part. The Ferron also generally thickens in the subsurface downdip from the outcrop. Records from wells and test holes indicate that the full thickness of the Ferron is saturated with water in most areas downdip from the outcrop area. Tests in the Emery area indicate that transmissivity of the Ferron sandstone aquifer ranges from about 200 to 700 feet squared per day where the Ferron is fully saturated. Aquifer transmissivity is greatest near the Paradise Valley-Joes Valley fault system where permeability has been increased by fracturing. Storage coefficient ranges from about 10 .6 to 10 -3 where the Ferron sandstone aquifer is confined and probably averages 5 x 10 -2 where it is unconfined.

Utah↗

USGS2022

Geologic characterization and depositional history of the Uteland Butte member, Green River Formation, southwestern Uinta Basin, Utah

The 15- to 65-m-thick informal Uteland Butte member of the Eocene Green River Formation represents the first widespread transgression of Lake Uinta in the Uinta Basin, Utah. This study assesses the spatial and temporal variation of Uteland Butte member deposits along a 40-km transect in the southwestern margin of the Uinta Basin using detailed measured sections, organic and inorganic geochemical data, and outcrop gamma ray logs. Fourteen lithofacies are identified, which comprise seven facies associations linked to with lacustrine, palustrine, and deltaic depositional settings. Facies associations are traceable laterally across the study area, where five 4- to 12-m-thick depositional cycles are identified. Each shallowing upwards cycle is defined by a >1.5-m-thick basal package of organic-rich, argillaceous laminated mudstone, and is capped by thick packages of bedded carbonate. In the far western study area (Kyune Creek Canyon), thick deposits of organic-rich mudstone are present and represent the most distal outcrop section; time-equivalent strata in the eastern study area (Minnie Maud Creek Canyon) are relatively organic lean with higher silt and clay content, interpreted to represent proximal lake margin deposits influenced by a nearby delta. The outcrop belt is correlated to more distal cores and well logs across the western Uinta Basin. Similar lithological and petrophysical patterns across the western Uinta Basin are used to subdivide stratigraphy into nine laterally contiguous sub-units based on nomenclature from the oil-producing area of the central basin (from base to top: lower Uteland Butte, D Bench, D Shale, C Bench, C Shale, B Bench, B Shale, A Bench, and A Shale). Siliciclastic clay-rich and carbonaterich intervals are correlated across the region and indicate distinct siliciclastic- and carbonate-dominated lake phases during Uteland Butte member deposition. Climate is interpreted to be the dominant driver of these claycarbonate cycles, in which relatively humid periods resulted in increased fluvially derived siliciclastic sediment into the basin (clay-rich periods), and arid periods resulted in evaporative conditions with decreased fluvial sediment input that favor carbonate accumulation. Climatically driven depositional cycles within the Uteland Butte member reflect, to a smaller degree, the larger scale climatically driven depositional cycles observed at the member- and formation levels of Paleocene and Eocene Uinta Basin stratigraphy. Importantly, the Uteland Butte member clay-carbonate cycles showcase how relatively small-scale climate shifts can impact basin-scale lacustrine deposition.

Utah↗

USGS2022

Geochemical studies of the Green River Formation in the Piceance Basin, Colorado: II. Chemofacies from hierarchical cluster analysis

Hierarchical cluster analysis (HCA) was applied to a geochemical dataset representing the Eocene Green River Formation in the Piceance Basin of Colorado to identify chemofacies in core and outcrop samples from the basin margin and the basin center. The input dataset consisted of inductively coupled plasma optical emission spectroscopy and mass spectrometry and total organic carbon (TOC) content analyses of 186 basin margin outcrop samples and 190 basin center core samples discussed in Part 1 of this study (this volume). TOC values and twenty-five major and trace elements were used as variables to define statistical clusters of samples for the overall dataset, for the two basin center cores, and for each separate core or outcrop dataset by HCA applying Euclidean distance and Ward’s method algorithms. For each dataset, five cluster-defined chemofacies were identified. The chemofacies for each dataset show chemical affinities with five informally defined rock types– mudstone, marlstone, carbonate-rich mudstone, siliciclastic-rich mudstone/siltstone/sandstone, and Na-rich (saline) mudstone, with each showing variations in TOC content and abundance of redox sensitive minor and trace elements. A close relationship between enrichment of redox sensitive elements, particularly As and Mo, and TOC is identified in the basin center. Whereas enrichment factors (relative to average shale) are relatively low for many Period IV (PIV) transition metals, as discussed in Part 1 of this study, their consistent coherence in enrichment or depletion in HCA-defined chemofacies demonstrates the expected relationship between redox state and organic richness. Enrichment in PIV transition metals also shows a correlation to enrichment in elements with affinity for siliciclastic sediment. Enrichment/depletion among several groups of redox indicators is not everywhere consistent, with some chemofacies showing, for example, enrichment of PIV transition metals and depletion of sulfur and arsenic. Early timing of saline conditions in the basin margin is clearly displayed in the chemofacies log display, consistent with observations based on geochemical interpretations of concentrations and elemental ratios discussed in Part 1. Overall, the chemofacies are consistent with major mineralogical units and lake history stages defined in previous work, but provide more detail on the fluctuations in lake chemistry that occurred during deposition of Green River oil shale in the Piceance Basin.

Colorado↗