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At least 1,099 records · Page 61Linked to original sources
USGS1991

Late Quaternary stratigraphy and depositional history of the Long Island Sound basin

The stratigraphy of Late Quaternary geologic units beneath Long Island Sound (LIS) is interpreted from 3,500 km of high-resolution, seismic-reflection profiles supplemented by vibracore data. Knowledge gained from onshore regional geologic studies and previous offshore investigations is also incorporated in these interpretations. Glacial deposits overlie and nearly fill an Inner Lowland which is floored by crystalline rocks in the north and bounded to the south by an irregular, north-facing cuesta scarp in Cretaceous Coastal-Plain strata. The thick glacial section consists largely of sediment that was deposited in glacial Lake Connecticut during the retreat of the last (late Wisconsin) ice sheet. Ice-marginal lacustrine fan deposits and submerged extensions of the southeastern Connecticut recessional moraines mark positions of the ice margin during systematic northward retreat. When the ice margin stood at positions just north of the present shoreline of Connecticut (17.6-16.5 ka), glacial Lake Connecticut was slightly larger than Long Island Sound is today. Ice-marginal deltas and near-ice marginal fluviodeltaic deposits occur along coastal Connecticut. Delta-building was diachronous; progressively younger deltas record northwesterly retreat of the ice margin and lowering lake levels. Distally from the deltas, varied lake-clays (up to 150 m thick) drape the underlying topography. The lake spillway cut across the Harbor Hill-Roanoke Point-Fishers Island-Charlestown end moraine at its lowest point just west of Fishers Island (The Race). Lake levels fell as the spillway notch was erosionally deepened, and gradually the lakebed became subaerially exposed. A largely preserved channel system cuts the lake-deposit surface; fluvial channel-fill sediments are overlain by estuarine sediments in the channel system. Perhaps as early as 15 ka, but no later than 13 ka, the sea entered the Basin through the channel at The Race and quickly transgressed westward via the lakebed channel system. As the sea rose further and spread throughout the Basin, a wave-cut surface was formed. Extensive marine deltaic deposits, up to 40 m thick, overlie the wave-cut marine unconformity in the east-central part of the Basin. These sediments were derived from erosion of the drained bed of Lake Hitchcock, in the Connecticut valley to the north, and were deposited in a -40-m relative sea at about 12.4 ka. Where quiet waters prevail, marine mud generally less than 15 m thick blankets the older deposits of the Basin. Elsewhere, especially in eastern LIS, tidal currents are actively reworking and transporting glacial and postglacial deposits.

Connecticut, New York↗
USGS2022

Tree regrowth duration map from LCMAP collection 1.0 land cover products in the conterminous United States, 1985–2017

Forest covers about one-third of the land area of the conterminous United States (CONUS) and plays an important role in offsetting carbon emissions and supporting local economies. Growing interest in forests as relatively cost-effective nature-based climate solutions, particularly restoration and reforestation activities, has increased the demand for information on forest regrowth and recovery following natural and anthropogenic disturbances (e.g., fire, harvest, or thinning). However, a wall-to-wall mapping of the CONUS tree regrowth duration at an annual time interval and 30-m resolution is still challenging. In this study, we utilized the annual land cover products to develop a dataset to quantify forest regrowth duration for CONUS over 1985–2017. The land cover data used to derive the tree regrowth duration map is from the primary land cover product in the U.S. Geological Survey’s Land Change Monitoring, Assessment, and Projection (LCMAP) collection. The LCMAP product used all available Landsat images to detect disturbances over forest and classify Grass/Shrub to Tree Cover transitions on an annual basis. The average regrowth duration was then calculated for each pixel. The regrowth duration map was validated using human interpreted annual reference data that were collected independently. The validation results show one-year of underestimation and 6-year standard deviation of error between the reference data and regrowth duration map. In southeastern CONUS, where major tree regrowth activities have been observed, our map showed higher accuracy with less than one-year bias and 3.6 years standard deviation of error. Forest in the southeast took around 5 years to recover, which was faster than other regions of CONUS. Many pixels had multiple disturbances during the 33-year study period in the region. The spatial pattern of the tree regrowth indicated intense harvesting activities in this region. The Pacific Northwest coast region was the second main area of tree regrowth, but this region often took multiple decades to recover. Given increasing interest in forests as nature-based climate solutions, the tree regrowth duration map can be used to assess reforestation activities as well as forest recovery following natural disturbance and harvesting.

Conterminous United States↗
USGS2009

Hydrogeology and Simulation of Groundwater Flow in the Plymouth-Carver-Kingston-Duxbury Aquifer System, Southeastern Massachusetts

The glacial sediments that underlie the Plymouth-Carver-Kingston-Duxbury area of southeastern Massachusetts compose an important aquifer system that is the primary source of water for a region undergoing rapid development. Population increases and land-use changes in this area has led to two primary environmental effects that relate directly to groundwater resources: (1) increases in pumping that can adversely affect environmentally sensitive groundwater-fed surface waters, such as ponds, streams, and wetlands; and (2) adverse effects of land use on the quality of water in the aquifer. In response to these concerns, the U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection, began an investigation in 2005 to improve the understanding of the hydrogeology in the area and to assess the effects of changing pumping and recharge conditions on groundwater flow in the Plymouth-Carver-Kingston-Duxbury aquifer system. A numerical flow model was developed based on the USGS computer program MODFLOW-2000 to assist in the analysis of groundwater flow. Model simulations were used to determine water budgets, flow directions, and the sources of water to pumping wells, ponds, streams, and coastal areas. Model-calculated water budgets indicate that approximately 298 million gallons per day (Mgal/d) of water recharges the Plymouth-Carver-Kingston-Duxbury aquifer system. Most of this water (about 70 percent) moves through the aquifer, discharges to streams, and then reaches the coast as surface-water discharge. Of the remaining 30 percent of flow, about 25 percent of the water that enters the aquifer as recharge discharges directly to coastal areas and 5 percent discharges to pumping wells. Groundwater withdrawals are anticipated to increase from the current (2005) rate of about 14 Mgal/d to about 21 Mgal/d by 2030. Pumping from large-capacity production wells decreases water levels and increases the potential for effects on surface-water bodies, which are affected by pumping and wastewater disposal locations and rates. Pumping wells that are upgradient of surface-water bodies potentially capture water that would otherwise discharge to these surface-water bodies, thereby reducing streamflow and pond levels. The areas most affected by proposed increases in groundwater withdrawals are in the Towns of Plymouth and Wareham where more than half of the proposed increase in pumping will occur. In response to an increase of about 7 Mgal/d of pumping, groundwater discharge to streams is reduced by about 6 cubic feet per second (ft3/s) (about 4 Mgal/d) from a total of about 325 ft3/s. Reduction in streamflow is moderated by an increase of artificial recharge from wastewater returned to the aquifer by onsite domestic septic systems and centralized wastewater treatment facilities. It is anticipated that about 3 Mgal/d of the 7 Mgal/d of increase in pumped water will be returned to the aquifer as wastewater by 2030. Currently (2005) about 3 percent of groundwater discharge to streams is from wastewater return flow to the aquifer during average conditions. During drought conditions, the component of streamflow augmented by wastewater return flow doubles as wastewater recharge remains constant and aquifer recharge rates decrease. Wastewater return flow, whether as direct groundwater discharge to streams or as an additional source of aquifer recharge, increases the height of the water table near streams, thereby moderating the effects of increased groundwater withdrawals on streamflow. An analysis of a simulated drought similar to the 1960s drought of record indicates that the presence of streams moderates the effects on water levels of reduced aquifer recharge. The area where water-table altitudes were least affected by drought was in the Weweantic River watershed in the Town of Carver. Water levels decreased by less than 2 feet from current average conditions compared to decreases of greater than 5

Scientific Investigations Report↗
USGS2012

Geologic implications of topographic, gravity, and aeromagnetic data in the northern Yukon-Koyukuk province and its borderlands, Alaska

The northern Yukon-Koyukuk province is characterized by low elevation and high Bouguer gravity and aeromagnetic anomalies in contrast to the adjacent Brooks Range and Ruby geanticline. Using newly compiled digital topographic, gravity, and aeromagnetic maps, I have divided the province into three geophysical domains. The Koyukuk domain, which is nearly equivalent to the Koyukuk lithotectonic terrane, is a horseshoe-shaped area, open to the south, of low topography, high gravity, and high-amplitude magnetic anomalies caused by an intraoceanic magmatic arc. The Angayucham and Kanuti domains are geophysical subdivisions of the Angayucham lithotectonic terrane that occur along the northern and southeastern margins of the Yukon-Koyukuk province, where oceanic rocks have been thrust over continental rocks of the Brooks Range and Ruby geanticline. Basalt of the Angayucham domain causes strong gravity highs and weak magnetic highs. The Kanuti domain is distinguished from the Angayucham domain by intense magnetic highs caused by cumulus mafic and ultramafic plutonic rocks, abundant ultramafic mantle tectonites, and magnetic syenite and monzonite. Long-wavelength, low-intensity magnetic highs and undulating gravity anomalies indicate an undulating basement surface of varied lithology beneath the Kobuk-Koyukuk and Lower Yukon basins. Modeling of gravity and magnetic anomalies shows that oceanic rocks of the Angayucham and Kanuti domains dip inward beneath the Kobuk-Koyukuk basin. The modeling supports, but does not prove, the hypothesis that the crust of the Kobuk-Koyukuk basin is 32–35 km thick, consisting of a tectonically thickened section of Cretaceous volcanic and sedimentary rocks and older oceanic crust. Plutons of the Brooks Range and the southern Ruby geanticline are nonmagnetic, ilmenite series, S-type granites that cause magnetic lows. Plutons of the northern Ruby geanticline are variable in their magnetic properties and cause both highs and lows. Plutons of both the eastern and western Yukon-Koyukuk province are variable in their magnetic expression but commonly cause magnetic lows in contrast to andesite.

Journal of Geophysical Research Solid Earth↗
USGS2022

U-Pb and fission-track data from zircon and apatite resolve latest- and post-Alleghanian thermal histories along the Fall Line of the Atlantic margin of the southeastern United States

Although the Atlantic continental margin of the eastern United States is an archetypal passive margin, episodes of rejuvenation following continental breakup are increasingly well documented. To better constrain this history of rejuvenation along the southern portion of this continental margin, we present zircon U-Pb (ZUPb) age, zircon fission-track (ZFT) age, apatite U-Pb (AUPb) age, and apatite fission-track (AFT) age and length data from six bedrock samples. The samples were collected along the boundary between the exposed Appalachian hinterland (Piedmont province) and the updip limit of passive margin strata (Coastal Plain province). The samples were collected from central Virginia southward to the South Carolina–Georgia border. ZUPb age distributions are generally consistent with geologic mapping in each of the sample areas. The AUPb data are highly discordant owing to high common-Pb abundances, but for two plutons at the northern and southern ends of the sample area, they define a discordia regression line that indicates substantial Permo-Triassic exhumation-driven cooling. ZFT age distributions are highly dispersed but define central values ranging from Permian to Jurassic. AFT data mostly appear to define a singular underlying cooling age, generally approximately Jurassic or Early Cretaceous. Apatite fission tracks are moderately long (mean lengths in the range of ~13.5 µm), however track lengths for one sample in central North Carolina are shorter (~12.5 µm). To interpret the post-breakup thermal history, we present inverse models of time-temperature history for the five plutonic samples. The models show a history of (1) rapid cooling (>10 °C/m.y.) from deep-crustal to near-surface temperatures by the Triassic, (2) hundreds of degrees of Triassic reheating, (3) Jurassic–Early Cretaceous cooling (at rates of 1–10 °C/m.y.), and (4) slow Late Cretaceous–Cenozoic cooling (~1 °C/m.y.). An additional suite of forward models is presented to further evaluate the magnitude of maximum Triassic reheating at one sample site that is particularly well constrained by thermal maturity data. The model results and geologic reasoning suggest that the inverse models may overestimate Triassic paleotemperatures but that other aspects of the inverse modeling are robust. Overall, this thermal history can be reconciled with several aspects of the lithostratigraphy of distal parts of the continental margin, including the lack of Jurassic–earliest Cretaceous strata beneath the southern Atlantic coastal plain and Cretaceous–Cenozoic grain-size trends.

Geosphere↗
USGS1956

Preliminary report on the geology and deposits of monazite, thorite, and niobium-bearing rutile of the Mineral Hill district, Lemhi County, Idaho

Deposits of minerals containing niobium (columbium), thorium, and rare earths occur in the Mineral Hill district, 30 miles northwest of Salmon, Lemhi County, Idaho. Monazite, thorite, allanite, and niobium-bearing rutile form deposits in metamorphic limestone layers less than 8 feet thick. The known deposits are small, irregular, and typically located in or near small folds. Minor faults are common. Monazite generally is coarsely crystalline and contains less than one percent thorium. Rutile forms massive lumps up to 3 inches across; it contains between 5 and 10 percent niobium. Rutile occurs in the northwestern half of the district, thorite in the central and southeastern parts. Monazite occurs in all deposits. Allanite is locally abundant and contains several percent thorium. Magnetite and ilmenite are also locally abundant. A major thrust fault trending northwest across the map-area separates moderately folded quartzite and phyllitic rocks of Belt age, on the northeast, from more intensely metamorphosed and folded rocks on the southwest. The more metamorphosed rocks include amphibolite, porphyroblastic feldspar gneiss, quartzite, and limestone, all probably of sedimentary origin, and probably also of Belt (late Precambrian) age. The only rocks of definite igneous origin are rhyolite dikes of probable Tertiary age. The more metamorphosed rocks were formed by metasomatic metamorphism acting on clastic sediments, probably of Belt age, although they may be older than Belt. Metamorphism doubtless was part of the episode of emplacement of the Idaho batholith, but the history of that episode is not well understood. The rare-element deposits show no evidence of fracture-controlled hydrothermal introduction, such as special fracture systems, veining, and gangue material. They may, however, be of hydrothermal type. More likely they are metamorphic segregations or secretions, deposited in favorable stratigraphic and structural positions during regional metamorphism.

Idaho↗
USGS2002

New Mexico structural zone - An analogue of the Colorado mineral belt

Updated aeromagnetic maps of New Mexico together with current knowledge of the basement geology in the northern part of the state (Sangre de Cristo and Sandia–Manzano Mountains)—where basement rocks were exposed in Precambrian-cored uplifts—indicate that the northeast-trending Proterozoic shear zones that controlled localization of ore deposits in the Colorado mineral belt extend laterally into New Mexico. The shear zones in New Mexico coincide spatially with known epigenetic precious- and base-metal ore deposits; thus, the mineralized belts in the two states share a common inherited basement tectonic setting. Reactivation of the basement structures in Late Cretaceous–Eocene and Mid-Tertiary times provided zones of weakness for emplacement of magmas and conduits for ore-forming solutions. Ore deposits in the Colorado mineral belt are of both Late Cretaceous–Eocene and Mid-Tertiary age; those in New Mexico are predominantly Mid-Tertiary in age, but include Late Cretaceous porphyry-copper deposits in southwestern New Mexico. The mineralized belt in New Mexico, named the New Mexico structural zone, is 250-km wide. The northwest boundary is the Jemez subzone (or the approximately equivalent Globe belt), and the southeastern boundary was approximately marked by the Santa Rita belt. Three groups (subzones) of mineral deposits characterize the structural zone: (1) Mid-Tertiary porphyry molybdenite and alkaline-precious-metal deposits, in the northeast segment of the Jemez zone; (2) Mid-Tertiary epithermal precious-metal deposits in the Tijeras (intermediate) zone; and (3) Late Cretaceous porphyry-copper deposits in the Santa Rita zone. The structural zone was inferred to extend from New Mexico into adjacent Arizona. The structural zone provides favorable sites for exploration, particularly those parts of the Jemez subzone covered by Neogene volcanic and sedimentary rocks.

Arizona, California, Colorado, Idaho, Montana, New↗
USGS2021

Synthesis of geochronologic research on Late Pliocene to Holocene emergent shorelines in the lower Savannah River area of southeastern Georgia, USA

Emergent late Pliocene and Pleistocene shoreline deposits, morphologically identifiable Pleistocene shoreline units, and seaward-facing scarps characterize the easternmost Atlantic Coastal Plain (ACP) of the United States of America. In some areas of the ACP, these deposits, units, and scarps have been studied in detail. Within these areas, temporal and spatial data are sufficient for time-depositional frameworks for shoreline-evolution to have been developed and published. For other areas, such as the southeastern Atlantic Coastal Plain (SEACP), available data are conflicting and (or) insufficient to develop such a framework, or to make shoreline correlations. Differential epeirogenic uplift and shoreline deformation, resulting from mantle-flow and climate-induced isostatic adjustments, complicate regional shoreline correlations. In the SEACP, the topographically prominent Orangeburg Scarp (hereafter, the Scarp) rises tens of meters in elevation from southeastern Georgia to southeastern North Carolina. The degree to which the Scarp and shoreline units seaward of the Scarp are deformed continues to be debated, but there is general agreement that the lower Savannah River area (LSRA) of Georgia and South Carolina is the least deformed area of the SEACP. This paper synthesizes published and previously unpublished numerical age and stratigraphic data for emergent Pliocene and younger shoreline deposits in the LSRA in Georgia. Age data are applied to these shoreline deposits as they are delineated (map units) on the 1976 geologic map of Georgia by Lawton and others. Age assignments are based on stratigraphic position, fossil content, soil and weathering diagnostic properties, and numerical ages as determined by meteoric Beryllium‑10 paleosol residence time ( 10 BePRT), optically stimulated luminescence (OSL), uranium disequilibrium series (U-series), amino acid racemization (AAR), and radiocarbon ( 14 C) analyses. These data provide a preliminary Pliocene-Pleistocene geochronology for the Orangeburg Scarp and shoreline deposits seaward of the Scarp in the LSRA of Georgia. Minimum ages and age ranges indicate the following: the Orangeburg Scarp formed sometime in the late Pliocene and early Pleistocene, between 3 Ma and 1 Ma; three, and possibly four, shoreline complexes were deposited in the middle Pleistocene; two shoreline complexes were deposited in the late middle and the late Pleistocene; deposition of the youngest shoreline complex began in the late Pleistocene and continues to the present; each shoreline complex was modified by multiple sea level highstands over time periods that lasted tens of thousands to hundreds of thousands of years; and Pleistocene shoreline chronology differs in part from modeled global sea level highstands.

Georgia, South Carolina↗
USGS2008

Dissolved-solids transport in surface water of the Muddy Creek Basin, Utah

Muddy Creek is located in the southeastern part of central Utah and is a tributary of the Dirty Devil River, which, in turn, is a tributary of the Colorado River. Dissolved solids transported from the Muddy Creek Basin may be stored in the lower Dirty Devil River Basin, but are eventually discharged to the Colorado River and impact downstream water users. This study used selected dissolved-solids measurements made by various local, State, and Federal agencies from the 1970s through 2006, and additional dissolved-solids data that were collected by the U.S. Geological Survey during April 2004 through November 2006, to compute dissolved-solids loads, determine the distribution of dissolved-solids concentrations, and identify trends in dissolved-solids concentration in surface water of the Muddy Creek Basin. The dissolved-solids concentration values measured in water samples collected from Muddy Creek during April 2004 through October 2006 ranged from 385 milligrams per liter (mg/L) to 5,950 mg/L. The highest dissolved-solids concentration values measured in the study area were in water samples collected at sites in South Salt Wash (27,000 mg/L) and Salt Wash (4,940 to 6,780 mg/L). The mean annual dissolved-solids load in Muddy Creek for the periods October 1976 to September 1980 and October 2005 to September 2006 was smallest at a site near the headwaters (9,670 tons per year [tons/yr]) and largest at a site at the mouth (68,700 tons/yr). For this period, the mean annual yield of dissolved solids from the Muddy Creek Basin was 44 tons per square mile. During October 2005 to September 2006, direct runoff transported as much as 45 percent of the annual dissolved-solids load at the mouth of Muddy Creek. A storm that occurred during October 5?7, 2006 resulted in a peak streamflow at the mouth of Muddy Creek of 7,150 cubic feet per second (ft3/s) and the transport of an estimated 35,000 tons of dissolved solids, which is about 51 percent of the average annual dissolved-solids load at the mouth of Muddy Creek. A significant downward trend in dissolved-solids concentrations from 1973 to 2006 was determined for Muddy Creek at a site just downstream of that portion of the basin containing agricultural land. Dissolved-solids concentrations decreased about 2.1 percent per year; however, the rate of change was a decrease of 1.8 percent per year when dissolved-solids concentrations were adjusted for flow.

Utah↗
USGS2012

Environmental settings of the South Fork Iowa River basin, Iowa, and the Bogue Phalia basin, Mississippi, 2006-10

Studies of the transport and fate of agricultural chemicals in different environmental settings were conducted by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program's Agricultural Chemicals Team (ACT) at seven sites across the Nation, including the South Fork Iowa River basin in central Iowa and the Bogue Phalia basin in northwestern Mississippi. The South Fork Iowa River basin is representative of midwestern agriculture, where corn and soybeans are the predominant crops and a large percentage of the cultivated land is underlain by artificial drainage. The Bogue Phalia basin is representative of corn, soybean, cotton, and rice cropping in the humid, subtropical southeastern United States. Details of the environmental settings of these basins and the data-collection activities conducted by the USGS ACT over the 2006-10 study period are described in this report.

Iowa;Mississippi↗
USGS2017

Effects of changes in pumping on regional groundwater-flow paths, 2005 and 2010, and areas contributing recharge to discharging wells, 1990–2010, in the vicinity of North Penn Area 7 Superfund site, Montgomery County, Pennsylvania

A previously developed regional groundwater flow model was used to simulate the effects of changes in pumping rates on groundwater-flow paths and extent of recharge discharging to wells for a contaminated fractured bedrock aquifer in southeastern Pennsylvania. Groundwater in the vicinity of the North Penn Area 7 Superfund site, Montgomery County, Pennsylvania, was found to be contaminated with organic compounds, such as trichloroethylene (TCE), in 1979. At the time contamination was discovered, groundwater from the underlying fractured bedrock (shale) aquifer was the main source of supply for public drinking water and industrial use. As part of technical support to the U.S. Environmental Protection Agency (EPA) during the Remedial Investigation of the North Penn Area 7 Superfund site from 2000 to 2005, the U.S. Geological Survey (USGS) developed a model of regional groundwater flow to describe changes in groundwater flow and contaminant directions as a result of changes in pumping. Subsequently, large decreases in TCE concentrations (as much as 400 micrograms per liter) were measured in groundwater samples collected by the EPA from selected wells in 2010 compared to 2005‒06 concentrations. To provide insight on the fate of potentially contaminated groundwater during the period of generally decreasing pumping rates from 1990 to 2010, steady-state simulations were run using the previously developed groundwater-flow model for two conditions prior to extensive remediation, 1990 and 2000, two conditions subsequent to some remediation 2005 and 2010, and a No Pumping case, representing pre-development or cessation of pumping conditions. The model was used to (1) quantify the amount of recharge, including potentially contaminated recharge from sources near the land surface, that discharged to wells or streams and (2) delineate the areas contributing recharge that discharged to wells or streams for the five conditions. In all simulations, groundwater divides differed from surface-water divides, partly because of differences in stream elevations and because of geologic structure and pumping. In the 1990 and 2000 simulations, all recharge in and near the vicinity of North Penn Area 7 discharged to wells, but in the 2005 and 2010 simulations some recharge in this area discharged to streams, indicating possible discharge of contaminated groundwater from North Penn Area 7 sources to streams. As the amount of groundwater withdrawals by wells has declined since 1990, the area contributing recharge to wells in the vicinity of North Penn Area 7 has decreased. To determine the effect of changes in pumping on flow paths and possible flow-path-related contributions to the observed changes in spatial distribution of contaminants in groundwater from 2005 to 2010, the USGS conducted simulations using the previously developed regional groundwater-flow model using reported pumping and estimated recharge rates for 2005 and 2010. Flow paths from recharge at known contaminant source areas to discharge locations at wells or streams were simulated under steady-state conditions for the two periods. Simulated groundwater-flow paths shifted only slightly from 2005 to 2010 as a result of changes in pumping rates. These slight changes in groundwater-flow paths from known sources of contamination are not coincident with the spatial distribution of observed changes in TCE concentrations from 2005 to 2010, indicating that the decreases of TCE concentrations may be a result of other processes, such as source removal or degradation. Results of the simulations and the absence of increases in TCE-degradation-product concentrations indicate that the decreases of TCE concentrations observed in 2010 may be at least partly related to contaminant-source removal by soil excavation completed in 2005, although additional data would be needed to confirm this preliminary explanation.

Pennsylvania↗
USGS1996

Effectiveness of highway-drainage systems in preventing road-salt contamination of ground water, southeastern Massachusetts

Road-salt contamination of public and private water supplies has become a serious and costly problem, particularly in the Northeast and Midwest. For example, reports of road-salt contamination from 100 of the 351 municipalities in Massachusetts from 1983 through 1990 required an expenditure of about 2.5 million dollar to investigate and remediate. Nationally, an estimated 10 million dollar are spent annual ly by State and local governments to prevent and remediate road-salt contamination. One method used by State highway agencies to reduce road- salt contamination of public-water supplies is to divert the salt-laden highway runoff through drainage systems from section of highway that pass near public-water supplies to less sensitive areas. The U.S. Geological Survey (USGS), in cooperation with the Massachusetts Highway Department (MHO), has conducted an investigation of the relative effectiveness of four highway-drainage systems in preventing road-salt contamination of ground water. This fact sheet describes the highway-drainage systems tested, the general hydrogeology of the study area, and the methods used to evaluate the drainage systems; and presents preliminary findings of the effectiveness of the systems in preventing road-salt contamination of ground water. These findings are based on data collected from November 1990 through May 1992. The re ult of this investigation will have wider application than just in the snow-belt regions of the United States, Canada, and Europe, as other contaminants in highway runoff either can be diverted from sensitive areas by drainage systems or allowed to seep into the ground, potentially contaminating ground water.

Massachusetts↗
USGS1994

Geologic history and hydrogeologic setting of the Edwards-Trinity aquifer system, west-central Texas

The Edwards-Trinity aquifer system underlies about 42,000 square miles of west-central Texas. Nearly flat-lying, mostly Comanche (Lower Cretaceous) strata of the aquifer system thin northwestward atop massive pre-Cretaceous rocks that are comparatively impermeable and structurally complex. From predominately terrigenous clastic sediments in the east and fluvialdeltaic (terrestrial) deposits in the west, the rocks of early Trinitian age grade upward into supratidal evaporitic and dolomitic strata, intertidal limestone and dolostone, and shallow-marine, openshelf, and reefal strata of late Trinitian, Fredericksburgian, and Washitan age. A thick, downfaulted remnant of mostly open-marine strata of Eaglefordian through Navarroan age composes a small, southeastern part of the aquifer system. The Trinity Group was deposited atop a rolling peneplain of pre-Cretaceous rocks during three predominately transgressive cycles of sedimentation that encroached upon the Llano uplift. The Fredericksburg and Washita Groups were deposited above the Trinity Group mostly in the lee of the Stuart City reef trend, a shelf margin ridge that sheltered depositional environments in the study area. The Washita Group subsequently was covered with thick, mostly fine-grained Gulf strata. During late Oligocene through early Miocene time, large-scale normal faulting formed the Balcones fault zone, where the Cretaceous strata were downfaulted, intensively fractured, and differentially rotated within a series of northeasttrending fault blocks. In addition to fracturing the rocks in the fault zone and extending the depth of freshwater diagenesis, the faulting vertically displaced the terrain, which steepened hydraulic gradients and maintained relatively high flow velocities near the surface. A shallow regime of dynamic ground-water flow evolved that promoted dissolution and enhanced the transmissivity of the Edwards Group in the Balcones fault zone. Cementation, recrystallization, and mineral replacement caused by deeper, comparatively sluggish ground-water circulation combined to diminish the transmissivity of the underlying Trinity Group, as well as most Cretaceous strata in the Hill Country, Edwards-Plateau, and Trans-Pecos. The Trinity, Fredericksburg, and Washita strata compose a regional aquifer system of three aquifers, whose water-transmitting characteristics generally are continuous in the lateral direction, and two hydraulically tight confining units. The aquifers are the Edwards aquifer in the Balcones fault zone, the Trinity aquifer in the Balcones fault zone and Hill Country, and the Edwards-Trinity aquifer in the Edwards Plateau and Trans-Pecos. The Navarro-Del Rio confining unit overlies the subcrop of the Edwards aquifer, and the Hammett confining unit lies within the updip, basal part of the Trinity aquifer and a small southeastern fringe of the Edwards-Trinity aquifer. The confining units are mostly calcareous mudstone, siltstone, and shale of low-energy terrigenous and openshelf marine depositional environments. The aquifers mainly result from fractures, joint cavities, and porosity caused by the dissolution of evaporites and unstable carbonate constituents. Because the diagenetic effects of cementation, recrystallization, and mineral replacement diminish the hydraulic conductivity of most rocks composing the Trinity and Edwards-Trinity aquifers, transmissivity values average less than 10,000 feet squared per day over more than 90 percent of the study area. However, the effects of tectonic fractures and dissolution in the Balcones fault zone cause transmissivity values to average about 750,000 feet squared per day in the Edwards aquifer, which occupies less than 10 percent of the study area.

Texas↗
USGS2004

Channel-morphology data for the Tongue River and selected tributaries, southeastern Montana, 2001-02

Coal-bed methane exploration and production have begun within the Tongue River watershed in southeastern Montana. The development of coal-bed methane requires production of large volumes of ground water, some of which may be discharged to streams, potentially increasing stream discharge and sediment load. Changes in stream discharge or sediment load may result in changes to channel morphology through changes in erosion and vegetation. These changes might be subtle and difficult to detect without baseline data that indicate stream-channel conditions before extensive coal-bed methane development began. In order to provide this baseline channel-morphology data, the U.S. Geological Survey, in cooperation with the Bureau of Land Management, collected channel-morphology data in 2001-02 to document baseline conditions for several reaches along the Tongue River and selected tributaries. This report presents channel-morphology data for five sites on the mainstem Tongue River and four sites on its tributaries. Bankfull, water-surface, and thalweg elevations, channel sections, and streambed-particle sizes were measured along reaches near streamflow-gaging stations. At each site, the channel was classified using methods described by Rosgen. For six sites, bankfull discharge was determined from the stage- discharge relation at the gage for the stage corresponding to the bankfull elevation. For three sites, the step-backwater computer model HEC-RAS was used to estimate bankfull discharge. Recurrence intervals for the bankfull discharge also were estimated for eight of the nine sites. Channel-morphology data for each site are presented in maps, tables, graphs, and photographs.

Open-File Report↗
USGS2022

Airborne electromagnetic survey results near the Poso Creek oil field, San Joaquin Valley, California, fall 2016

An airborne electromagnetic survey west of the Poso Creek oil field, located in the southeastern San Joaquin Valley, California, was flown in October 2016 to improve understanding of the hydrogeologic setting and the distribution of groundwater salinity in the area. The airborne electromagnetic data were used to develop resistivity models of the subsurface, where the mean depth of investigation is about 300 meters below the land surface and thus characterizes parts of the Kern River Formation and overlying sediments. Resistivity models along with water table elevation, historical total dissolved solids measurements of water samples from wells, well lithologic records, borehole geophysical logs, and mapped surface geology were used to develop an understanding of local hydrogeologic controls on resistivity. Interpretation of these data indicate the resistivity structure primarily reflects the general lithologic character and geologic structure of the study area, with more subtle influences from variations in saturation and salinity.

California↗
USGS2001

Relationship of faults in basin sediments to the gravity and magnetic expression of their underlying fault systems

Gravity and magnetic surveys were performed along the western flanks of the Santa Rita Mountain range located in southeastern Arizona to develop an understanding of the relationship between surface fault scarps within the basin fill sediments and theirgeophysical response of the faults at depth within the bedrock. Data were acquired for three profiles, one of them along the northern terrace of Montosa Canyon, and the other two along the northern and southern terraces of Cottonwood Canyon. A total of 122 gravity stations were established as well as numerous magnetic data collected by a truckmounted cesium-vapor magnetometer. In addition, aeromagnetic data previously acquired were interpreted to obtain a geologically sound model, which produced a good fit to the data. Gravity anomalies associated with faults exhibiting surface rupture were more pronounced than the respective magnetic anomalies. More credence was given to the gravity data when determining fault structures and it was found in all three profiles that faults at depth projected through alluvium at a steeper dip than the bedrock fault indicating brittle behavior within the overlying sediments. The gravity data also detected a significant horst and graben structure within Cottonwood Canyon. The aeromagnetic data did not provide any insight into the response of the minor faults but rather served to verify the regional response of the whole profile.

Arizona↗
USGS1994

Ground-water levels and directions of flow near the Industrial Excess Landfill, Uniontown, Ohio, March 1994

Industrial Excess Landfill (IEL), a U.S. Environmental Protection Agency Superfund site, is a closed landfill in northeastern Ohio. In March 1994, personnel from the U.S. Geological Survey, Ohio Environmental Protection Agency, and PRC Environmental Management, Inc., measured water levels in 149 wells in the area. Surface-water altitudes were measured at 13 staff gages, and water levels were measured in 9 piezometers associated with the gages. The data show that the regional pattern of ground-water flow generally is from east to west, but it is locally altered by ground-water mounds that reflect the hummocky terrain. At the landfill, regional flow is altered by two ground-water mounds one in the southeastern corner of the site and one just to the north. The relatively small ground-water mound at the landfill causes ground water to flow radially away from the southeastern corner of the landfill. Ground water that flows to the east and south flows toward Metzger Ditch, whereas flow to the west is consistent with the regional direction of ground-water flow. Ground-water flow northward from IEL is diverted east or west by the southerly component of flow from the larger ground-water mound north of IEL.

Ohio↗
USGS1988

Geologic map of the northwestern Caliente Range, San Luis Obispo County, California

The map area lies in the southern Coast Ranges of California, north of the Transverse Ranges and west of the southern San Joaquin Valley. This region is part of the Salinia-Tujunga composite terrane that is bounded on the northeast by the San Andreas fault (fig. 1) and on the southwest by the Nacimiento fault zone (Vedder and others, 1983). The Chimineas fault of this map is inferred to be the boundary between the Salinia and the Tujunga terranes (Ross, 1972; Vedder and others, 1983). Geologic mapping in the region of the California Coast Ranges that includes the area of this map has been largely the work of T.W. Dibblee, Jr. Compilations of geologic mapping at a scale of 1:125,000 (Dibblee, 1962, 1973a) provide the regional setting for this map, the northeast border of which lies about 6 to 7 km southwest of the San Andreas fault. Ross (1972) mapped the crystalline basement rocks in the vicinity of Barrett Creek, along the northeast side of the Chimineas fault ("Barrett Ridge" of Ross, 1972). Recent 1:24,000-scale mapping in the La Panza Range (fig. 1) (Vedder and others 1986a,b) overlaps onto the southwest edge of this map and provides useful information about the older rocks, mostly southwest of San Juan Creek. Stratigraphic knowledge of the area, which lies in the northern part of the middle Tertiary Cuyama basin, has evolved over a period of years beginning with the molluscan biostratigraphic work of Anderson and Martin (1914) and Loel and Corey (1932). Hill and others (1958) described the Tertiary stratigraphy of the region and proposed stratigraphic names. This stratigraphy was discussed further by Dibblee (1973b), and his revised nomenclature is used here. Stratigraphic studies in the southeastern Caliente Range (fig. 1) (Repenning and Vedder, 1961; Vedder, 1973) provided valuable information on the interrelations of continental, shallow-marine, and deeper marine facies in the southern part of the Cuyama basin, which have basinwide application. More recent stratigraphic studies by Lagoe (1984, 1985, 1987, 1988) further elaborate on aspects of Miocene basin history and paleogeography. Contributions to the tectonic history of the area have been made by Schwade and others (1958), on the basis of oil exploration in the Cuyama Valley area (fig. 1) in the 1940's and 1950's; by Bartow (1974), as part of a regional stratigraphic study; by Ballance and others (1983), on the basis of a study of Oligocene and early Miocene sedimentation; and most recently by Davis and others (1988) and Yeats and others (1988), who utilized a variety of new data from seismic reflection and from stratigraphic and structural studies. Field work for this map was done mostly in 1969-73 as part of a regional study of the Simmler and Vaqueros Formations (Bartow, 1974). Detailed field mapping was, therefore, concentrated on those units; other parts of the area were mapped by geologic reconnaissance and air-photo interpretation that were supplemented by data from published maps (Dibblee, 1973a; Vedder and others, 1986a,h). Mapping of the crystalline basement rocks at "Barrett Ridge" is from Ross (1972, plate 1). The structural style depicted in the accompanying cross sections favors the thrust belt concepts of Davis and others (1988) over the older interpretations of Dibblee (1962) or Cross (1962).

California↗