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At least 955 records · Page 53Linked to original sources
USGS2010

Estimating salinity intrusion effects due to climate change on the Lower Savannah River Estuary

The ability of water-resource managers to adapt to future climatic change is especially challenging in coastal regions of the world. The East Coast of the United States falls into this category given the high number of people living along the Atlantic seaboard and the added strain on resources as populations continue to increase, particularly in the Southeast. Increased temperatures, changes in regional precipitation regimes, and potential increased sea level may have a great impact on existing hydrological systems in the region. The Savannah River originates at the confluence of the Seneca and Tugaloo Rivers, near Hartwell, Ga., and forms the state boundary between South Carolina and Georgia. The J. Strom Thurmond Dam and Lake, located 238 miles upstream from the Atlantic Ocean, is responsible for most of the flow regulation that affects the Savannah River from Augusta, Ga., to the coast. The Savannah Harbor experiences semi-diurnal tides of two low and two high tides in a 24.8-hour period with pronounced differences in tidal range between neap and spring tides occurring on a 14-day and 28-day lunar cycle. Salinity intrusion results from the interaction of three principal forces - streamflow, mean tidal water levels, and tidal range. To analyze, model, and simulate hydrodynamic behaviors at critical coastal streamgages in the Lower Savannah River Estuary, data-mining techniques were applied to over 15 years of hourly streamflow, coastal water-quality, and water-level data. Artificial neural network (ANN) models were trained to learn the variable interactions that cause salinity intrusions. Streamflow data from the 9,850 square-mile Savannah River Basin were input into the model as time-delayed variables. Tidal inputs to the models were obtained by decomposing tidal water-level data into a “periodic” signal of tidal range and a “chaotic” signal of mean water levels. The ANN models were able to convincingly reproduce historical behaviors and generate alternative scenarios of interest. Important freshwater resources are located proximal to the freshwater-saltwater interface of the estuary. The Savannah National Wildlife Refuge is located in the upper portion of the Savannah River Estuary. The tidal freshwater marsh is an essential part of the 28,000-acre refuge and is home to a diverse variety of wildlife and plant communities. Two municipal freshwater intakes are located upstream from the refuge. To evaluate the impact of climate change on salinity intrusion on these resources, inputs of streamflows and mean tidal water levels were modified to incorporate estimated changes in precipitation patterns and sea-level rise appropriate for the Southeastern United States. Changes in mean tidal water levels were changed parametrically for various sea-level rise conditions. Preliminary model results at the U.S. Geological Survey (USGS) Interstate-95 streamgage (station 02198840) for a 7½-year simulation show that historical daily salinity concentrations never exceeded 0.5 practical salinity units (psu). A 1-foot sea-level rise (ft, 30.5 centimeters [cm]) would increase the number of days of salinity concentrations greater than 0.5 psu to 47 days. A 2-ft (61 cm) sea-level rise would increase the number of days to 248.

Georgia, South Carolina↗
USGS2019

Regional protocol framework for the inventory and monitoring of breeding Atlantic Coast Piping Plovers

This regional protocol provides a framework for quantifying the number of breeding pairs and productivity of Atlantic Coast piping plover (Charadrius melodus) populations during the breeding season. A primary purpose of this protocol is to standardize piping plover monitoring during the breeding season. The survey techniques described herein involve repeated visual counts of adults, nests, eggs, and chicks within a defined survey site (i.e., beach) as well as visual identification of potential threats to survival and productivity. Resulting data can be compiled and analyzed across multiple geographic units (i.e., sites, states, and recovery units) to assess progress toward recovery goals, inform local management decisions, assess management effectiveness, and improve monitoring efforts. This protocol framework was developed as part of the United States Fish and Wildlife Service (USFWS) National Wildlife Refuge System (NWRS) Inventory and Monitoring (I&M) Initiative in coordination with Ecological Services (ES) and state coordinators within the Southeast and Northeast Regions (4 and 5, respectively). Although this protocol framework is to be used primarily by NWRS to inform recovery goals, assist with local management decision-making, and meet State reporting requirements, the approach strives to assist monitoring efforts of nonNWRS partners, such as other federal agencies (e.g. National Park Service), State wildlife agencies, non-governmental organizations, and private landowners. This protocol framework and associated data management system (PIPLweb) aims to interface with existing data management and analysis tools (i.e., PIPLODES, NestStory, and PiperEx) to ensure that data collection is efficient and comparable across scales, and supports management decisions across partners. The content and structure of the protocol framework follows standards set forth in the USFWS’s How to Develop Survey Protocols: A Handbook (Version 1.0; 2013). The eight elements addressed include: introduction, sampling design, field methods, data management and analysis, reporting, personnel requirements and training, operational requirements, and references. A series of standard operating procedures (SOPs) provides greater detail on recommended methods and technical aspects of this protocol. Data entry, archival, and multi-scale analysis are handled through a secure web application (Plover Inventory and Productivity Library; PIPLweb) developed by the United States Geological Survey (USGS). When management activities and survey objectives are similar across management units, partners (Refuges, other federal agencies, State, NGOs, private) are encouraged to use this protocol framework to develop stepped-down site-specific survey protocols that include guidance for conducting on-the-ground monitoring and management plans.

Regional Protocol Framework↗
USGS2016

The Outer Banks of North Carolina

The Outer Banks of North Carolina are excellent examples of the nearly 300 barrier islands rimming the Atlantic and Gulf coasts of the United States. These low, sandy islands are among the most dynamic natural landscapes occupied by man. Beach sands move offshore, onshore, and along the shore in the direction of the prevailing longshore currents. In this way, sandy coasts continuously adjust to different tide, wave, and current conditions and to rising sea level that causes the islands to migrate landward. Despite such changes, barrier islands are of considerable environmental importance. The Outer Banks are home to diverse natural ecosystems that are adapted to the harsh coastal environment. Native species tend to be robust and many are specifically adapted to withstand salt spray, periodic saltwater flooding, and the islands’ well-drained sandy soil. The Outer Banks provide an important stopover for birds on the Atlantic flyway, and many species inhabit the islands year round. In addition, Outer Banks beaches provide an important nesting habitat for five endangered or threatened sea turtle species. European explorers discovered North Carolina’s barrier islands in the 16th century, although the islands were not permanently settled until the middle 17th century. By the early 19th century, shipbuilding and lumber industries were among the most successful, until forest resources were depleted. Commercial fishing eventually followed, and it expanded considerably after the Civil War. By the Great Depression, however, little industry existed on the Outer Banks. In response to the effects of a severe hurricane in 1933, the National Park Service and the Civilian Conservation Corps proposed a massive sand-fixation program to stabilize the moving sand and prevent storm waves from sweeping across the entire width of some sections of the islands. Between 1933 and 1940, this program constructed sand fencing on 185 kilometers (115 miles) of beach and planted grass seedlings, trees, and shrubs. In 1937, Congress authorized the Cape Hatteras National Seashore, which was established in 1953. The national seashore preserved one of the world’s best examples of a barrier island environment, and minimized the effect of erosion that was becoming a serious problem. In 1966, Congress authorized the Cape Lookout National Seashore to ensure that Core and Shackleford Banks would not undergo major development and could be preserved in their natural state. The rate of population growth along the Outer Banks in recent decades has been among the highest in North Carolina. More important, however, has been the growth in vacationers—in 2008, more than a quarter of a million visitors during a typical week. Municipalities now need to provide services to a transient population as much as six times as large as their permanent resident population. Although human activities have dominated the landscape changes observed on the Outer Banks for the past century or two, these changes must be understood in the context of the prevailing atmospheric, oceanic, and geologic processes that have governed the form and function of these islands for thousands of years. It is these natural processes that imbue the Outer Banks with their unique and dichotomous qualities of tranquility and tumult. In the presence of human occupation, it is these same processes that make the islands one of the highest natural-hazard risk zones along the Eastern Seaboard of the United States.

North Carolina↗
USGS2000

Regoliths of the middle-Atlantic Piedmont and evolution of a polymorphic landscape

The regolith overlying the alumino-silicate rocks of the middle-Atlantic Piedmont Province consists primarily of saprolite with a thin veneer of diamictons of colluvial origin. Thickness and distribution of the saprolite is related to landform and lithology. For example, on uplands isovolumetric weathering of the Loch Raven Schist produces saprolite averaging 55 ft (17 m) thick. On Port Deposit Gneiss, saprolite beneath uplands averages 42 ft (13 m) in thickness. The saprolite results from the reaction of alumino-silicate rocks with through-flowing groundwater. Chemical weathering of the rock results in clay and resistate minerals, residual rock layers, corestones, and pinnacles. Surface erosion of saprolite with quartzite and metagraywacke residual layers may produce a 'washboard' topography. Surface erosion of a metagabbro saprolite containing corestones and pinnacles results in a surface with lag deposits of corestones and emergent pinnacles. The diamicton material comes from the underlying saprolite, weathered rock and bedrock. Generally, diamictons are thinner on uplands and upper slopes, and thicker at the base of slopes and in hollows and gathering areas of first-order streams. The saprolite and colluvium reflect response of geomorphic processes (chemical weathering, fluvial incision, and periglacial processes) to rock lithology and landscape. The modifications to the landscape have been driven by neotectonic crustal warping and alternating periglacial-humid temperate climates. Altogether these varied interactions have resulted in a Holocene polymorphic landscape.

Southeastern Geology↗
USGS1969

Distribution of oxygen and carbon isotopes in fossils of late cretaceous age, western interior region of North America

The oxygen isotope composition of both calcite and aragonite of the pelecypod Inoceramus is lighter than the composition of the aragonite of associated baculites and other cephalopods from the western interior region, the Gulf and Atlantic Coastal Plains, parts of Canada, and West Greenland. This difference cannot be explained by biotic and oceanographic factors or by postdepositional alteration of original isotopic compositions. Metabolic fractionation of oxygen isotopes by Inoceramus is strongly implied by the data and is not contradicted by what is known of the processes involved in the biologic deposition of shell carbonate. In addition, the oxygen isotope compositions of the inocerams and of some baculites are so light as to indicate temperatures greater than 30° C, which is too high for mollusks to tolerate. The unreasonable range of the indicated temperatures seems to be partly the result of metabolic fractionation of oxygen and partly the result of the Late Cretaceous sea in the western interior region having had a light oxygen isotope composition because of dilution with fresh water. The carbon isotope composition of the aragonite from Inoceramus is consistently heavier than that of the calcite in the same specimen by amounts ranging from 1 to 3 per mil. Metabolic fractionation of carbon isotopes within Inoceramus thus is indicated. The carbon isotope composition of the aragonite from baculites and other cephalopods is consistently lighter than that in either the aragonite or calcite in Inoceramus, indicating either that the cephalopods fractionated carbon isotopes from the dissolved carbonate in sea water differently than did inocerams or that the cephalopods utilized carbon of a different isotopic composition, probably from their food source, for their metabolic processes. While oxygen isotope data from the inocerams are not useful for paleotemperature interpretations, the oxygen isotope data from the baculites, if taken at face value, suggest either warmer temperatures for the western interior sea than around the periphery of Cretaceous North America, or water of oxygen isotope composition lighter than world oceans, or both. Data from British Columbia, southeastern Alaska, and West Greenland to the Gulf Coastal Plain do not indicate a well-developed latitudinal distribution of temperature in Late Cretaceous time. A general decline in temperatures during late Campanian and early Maestrichtian time is not evident. © 1969, The Geological Society of America, Inc.

Geological Society of America Bulletin↗
USGS2018

Subsurface controls on the development of the Cape Fear Slide Complex, central US Atlantic Margin

The Cape Fear Slide is one of the largest (>25 000 km 3 ) submarine slope failure complexes on the US Atlantic margin. Here we use a combination of new high-resolution multichannel seismic data (MCS) from the National Science Foundation Geodynamic Processes at Rifting and Subducting Margins (NSF GeoPRISMS) Community Seismic Experiment and legacy industry MCS to derive detailed stratigraphy of this slide and constrain the conditions that lead to slope instability. Limited outer-shelf and upper-slope accommodation space during the Neogene, combined with lowstand fluvial inputs and northwards Gulf Stream sediment transport, appears to have contributed to thick Miocene and Pliocene deposits that onlapped the lower slope. This resulted in burial of an upper-slope bypass zone developed from earlier erosional truncation of Paleogene strata. These deposits created a broad ramp that allowed accumulation of thick Quaternary strata across a low-gradient (<3.5°) upper slope. Upslope of one of the larger headwalls, undulating Quaternary strata appear to downlap onto a buried failure plane. Many of the nested headwalls of the upper-slope portion of slide complex are underlain by deformed strata, which may be the result of fluid migration associated with localized subsidence from salt migration. These new data and observations suggest that antecedent margin physiography, sediment loading and substrate fluid flow were key factors in preconditioning the Cape Fear slope for failure.

Geological Society of London Special Publications↗
USGS1973

Glauconites from New Jersey-Maryland coastal plain: Their K-Ar ages and application in stratigraphic studies

Glauconite samples from various stratigraphic levels in the northern Atlantic Coastal Plain were dated by the K-Ar method. Twenty-eight samples were collected from glauconite-bearing sands in four traverses across the outcrop belt of Upper Cretaceous–lower Tertiary formations from northern New Jersey to eastern Maryland, thus providing a framework on which to test the reliability of glauconite for dating in vertical sequences and within some formations along strike. Sample ages were determined paleontologically and radiogenically. The results show that most radiogenic determinations of glauconite followed a systematic pattern; the resultant ages were generally younger upward through the Stratigraphic section. In addition, consistent ages were obtained from many of the stratigraphic units along strike. A combination of paleontologically derived ages and the numerical radiogenic ages suggests that the stages of the Late Cretaceous are unequal rather than equal as some have proposed. For example, Campanian and Paleocene times are of significantly greater duration than the Maestrichtian. Several samples obtained across the Cretaceous-Tertiary boundary indicate that the age of the boundary is between 63.2 and 59.1 m.y., probably very near 61.1 m.y. Dates considered to be reliable were obtained from 25 of 28 samples. Two of the three discordant ages are ascribed to incomplete glauconitization of the pre-existing mineral phase and hence to mineral impurity. No adequate explanation for the third significantly younger age has been determined.

Delaware, Maryland, New Jersey, Pennsylvania↗
USGS2022

Pennsylvania and Landsat

The Commonwealth of Pennsylvania straddles an array of landscapes. From east to west, its 46,055 square miles connect the sea-level lowlands of the Atlantic seaboard with the rolling hills of the Midwest. It also acts as a bridge between regions from north to south, with the Appalachian Mountains swooping through its center from its northern border with New York to its southern borders with Maryland and West Virginia. The Declaration of Independence and U.S. Constitution were signed in the Commonwealth’s largest city, Philadelphia, and it was the second of the original 13 colonies to ratify the Constitution. The pivotal Civil War battle of Gettysburg took place in the southern part of Pennsylvania. Western Pennsylvania was an early hub for the coal, oil, and steel industries that fueled the Nation’s growth in the 20th century and still factor into Pennsylvania’s economy. The varied natural features of Pennsylvania have been an important proving ground for the value of satellite imagery from the USGS Landsat Program. Scientists began to lean on Landsat observations early in the program’s history to map the effect of invasive moths on Commonwealth forests. That activity continues to this day. Space-based imagery has also contributed to the study and management of land change from energy development, urban growth, and shifting land use patterns. The Landsat Program’s unparalleled 50-year archive of repeat Earth observations remains a critical public resource for Pennsylvania as environmental changes and land use patterns present new challenges to land managers and urban planners in the Keystone State.

Pennsylvania↗
USGS2003

Hydrogeology and Ground-Water Quality of Brunswick County, North Carolina

Brunswick County is the southernmost coastal county in North Carolina and lies in the southeastern part of the Coastal Plain physiographic province. In this report, geologic, hydrologic, and chemical data were used to investigate and delineate the hydrogeologic framework and ground-water quality of Brunswick County. The major aquifers and their associated confining units delineated in the Brunswick County study area include, from youngest to oldest, the surficial, Castle Hayne, Peedee, Black Creek, upper Cape Fear, and lower Cape Fear aquifers. All of these aquifers, with the exception of the Castle Hayne aquifer, are located throughout Brunswick County. The Castle Hayne aquifer extends across only the southeastern part of the county. Based on available data, the Castle Hayne and Peedee confining units are missing in some areas of Brunswick County, which allows direct hydraulic contact between the surficial aquifer and underlying Castle Hayne or Peedee aquifers. The confining units for the Black Creek, upper Cape Fear, and lower Cape Fear aquifers appear to be continuous throughout Brunswick County. In examining the conceptual hydrologic system for Brunswick County, a generalized water budget was developed to better understand the natural processes, including precipitation, evapotranspiration, and stream runoff, that influence ground-water recharge to the shallow aquifer system in the county. In the generalized water budget, an estimated 11 inches per year of the average annual precipitation of 55 inches per year in Brunswick County is estimated to infiltrate and recharge the shallow aquifer system. Of the 11 inches per year that recharges the shallow system, about 1 inch per year is estimated to recharge the deeper aquifer system. The surficial aquifer in Brunswick County is an important source of water for domestic supply and irrigation. The Castle Hayne aquifer is the most productive aquifer and serves as the principal ground-water source of municipal supply for the county. The upper part of the Peedee aquifer is an important source of ground-water supply for domestic and commercial use. Ground water in the lower part of the Peedee aquifer and the underlying aquifers is brackish and is not known to be used as a source of supply in Brunswick County. Most of the precipitation that recharges the surficial aquifer is discharged to local streams that drain into the Waccamaw River, Cape Fear River, and Atlantic Ocean. Recharge to the Castle Hayne aquifer occurs primarily from the surficial aquifer. Recharge to the Peedee aquifer occurs primarily from the surficial and Castle Hayne aquifers, with some upward leakage of water also occurring from the underlying Black Creek aquifer. Discharge from the Castle Hayne and Peedee aquifers occurs to local streams, the Cape Fear River, and the Atlantic Ocean. Evaluation of water-level data for the period January 1970 through May 2002 indicated no apparent long-term temporal trends in water levels in the surficial and Castle Hayne aquifers and in the upper part of the Peedee aquifer. The most significant water-level trends were noted for wells tapping the lower part of the Peedee aquifer and tapping the Black Creek aquifer where water levels have declined as much as 41 and 37 feet, respectively. These ground-water-level declines are attributed to regional ground-water pumping in areas outside of Brunswick County. Water-level data for Brunswick County wells tapping the upper Cape Fear and lower Cape Fear aquifers tend to fluctuate within a fairly uniform range with no apparent temporal trend noted. Analysis of vertical hydraulic gradients during this same period primarily indicate downward flow of ground water within and among the surficial, Castle Hayne, and Peedee aquifers. The vertical flow of ground water in the Black Creek aquifer is upward into the overlying Peedee aquifer. Upward flow also is noted for the upper and lower Cape Fear aquifers. Historic and recent analytic data were evaluated to better understand the sources of water contained in Brunswick County aquifers and the suitability of the water for consumption. Based on analytical results obtained for recent samples collected during this study, ground water from the surficial aquifer, Castle Hayne aquifer, and upper part of the Peedee aquifer appears to be generally suitable for drinking water. Although concentrations of iron and manganese commonly exceeded the drinking-water standards, the concern generally associated with the occurrence of these analytes in a water supply is one of aesthetics. In all samples, nitrate, nitrite, and sulfate were detected at concentrations less than drinkingwater standards. Based on historic analytical data, the brackish water in the lower part of the Peedee aquifer and in the Black Creek, upper Cape Fear, and lower Cape Fear aquifers is classified as a sodium-chloride type water. The presence of brackish water in these deeper systems combined with upward vertical gradients presents the potential for upward migration of brackish water into overlying aquifers, or upconing beneath areas of pumping. The current (2001) location of the boundary between freshwater and brackish water in Brunswick County aquifers is unknown.

North Carolina↗
USGS2002

Rates and patterns of late Cenozoic denudation in the northernmost Atlantic Coastal Plain and Piedmont

Topography of a 2800 km2 section of the U.S. Atlantic Coastal Plain and Piedmont is reconstructed at five times from the late Miocene to the Holocene. The reconstructions are based on mapping of fluvial, colluvial, and marginal-marine deposits that are dated by radiocarbon, palynostratigraphy, and correlation to adjacent glacial and marine units. Denudation rates and patterns are calculated by subtracting successive topographies, with 60 m horizontal resolution and 6 m vertical resolution. The overall late Miocene to Holocene denudation rate of 10 m/m.y. is similar to other estimates of long-term denudation in the region. The overall rate resolves spatially into a wide range of local rates, varying from a minimum of ???0.2 m/m.y. on residual uplands to as high as 600 m/m.y. in glacially rerouted stream channels. The distribution of local rates shows that denudation is accomplished by stream incision in response to long-term glacio-eustatic decline, followed by slope retreat into residual uplands from the incised channels. Slope retreat replaces the uplands with pediments and straths. Pediment landforms and sediments, and observation of modern scarps and valley heads, indicate that groundwater seepage from the base of residual uplands is an important mechanism of slope retreat. This process is self-limiting because as the volume of residual upland is reduced, seepage diminishes and slope retreat slows until small residuals undergo little or no further reduction. Thus, relict topography is preserved even as most of the landscape actively erodes.

Geological Society of America Bulletin↗
USGS2025

Multidecadal change in pesticide concentrations relative to human health benchmarks in the Nation’s groundwater

Groundwater-quality trend assessments identify aquifers that are responding to changes in pesticide use and the compounds that may pose a threat to water availability. The U.S. Geological Survey has been monitoring pesticide concentrations in groundwater for 25 principal aquifers across the conterminous United States since 1993. The groundwater well locations represent a range of soils, climate, and landforms. The wells are used to monitor groundwater underlying selected agricultural and urban settings and groundwater used for domestic supply. This study examined changes in relative concentrations, defined here as the percentage of wells with pesticide concentrations exceeding a human health benchmark (HHB). HHBs used in this report are legally enforceable drinking-water standards and nonenforceable drinking water levels. Relative pesticide concentration increases may lead to decreased water availability, as restrictions may be put in place for groundwater used as a drinking-water source. This study focused on concentration changes in 22 pesticides that were included in laboratory analysis from 1993 to 2023. The analysis and interpretation of these pesticide concentrations in groundwater have been separated into approximate decadal intervals (decade 1 (1993–2001), decade 2 (2002–12), and decade 3 (2013–22). For one pesticide, 1,2-dibromo-3-chloropropane (DBCP), concentration data were also collected in decade 4 (2023–onward). Atrazine, deethylatrazine, alachlor, prometon, and simazine were 5 pesticides detected at moderate concentrations (greater than 10 percent of the HHB but less than or equal to the HHB). The percentage of wells that had groundwater pesticide concentrations in the moderate concentration category decreased from 7 percent in decade 1 to 2 percent in decade 3. The agricultural networks had the highest percentages of wells with moderate concentrations, and these percentages decreased from 13 percent in decade 1 to 4 percent in decade 3. Moderate concentrations in the urban networks decreased between decades 1 and 2 from 4 percent to 0 percent. No moderate concentrations occurred in the urban networks in decade 3. The percentage of wells with moderate concentrations in the domestic supply networks (1 percent) was the lowest of all the network types and did not change across the three decades. Moderate atrazine or deethylatrazine concentrations occurred across all three decades in aggregated ecoregions representing similar soils, climate, and landforms in the Semiarid West, Midcontinent, and Northeastern United States. Moderate concentrations of prometon, alachlor, and simazine also occurred in the Midcontinent, Arid West, Northeast, South Atlantic Gulf, and Semiarid West regions, but the moderate concentrations did not persist across all three decades. DBCP was the only pesticide that exceeded its respective HHB, and the exceedances occurred across all four decades. In this report, the DBCP analysis was limited to one well network in the Central Valley, California. Agricultural use of DBCP was suspended in 1977. Forty-five years after being banned, DBCP concentrations were greater than the maximum contaminant level of 2 micrograms per liter (μg/L), but the number of exceedances decreased from 50 percent to 15 percent of the samples between 1993 and 2023. This assessment of decadal groundwater pesticide concentrations provides a characterization of changes in water availability because of pesticide contamination in areas where groundwater is used as a drinking-water source. The results highlight the importance of continued long-term monitoring and assessment of groundwater pesticides to identify locations and specific compounds that may pose a potential risk to human health.

continental United States↗
USGS1963

Geology and ground-water conditions in southern Nassau and southeastern Queens Counties, Long Island, N.Y.

Test drilling, electrical logging, and water sampling of 'outpost' and other wells have revealed the existence of a deep confined body of salt water in the Magothy(?) formation beneath southwestern Nassau and southeastern Queens Counties, Long Island, N.Y. In connection with a test-drilling program, cooperatively sponsored by the U.S. Geological Survey, the Nassau County Department of Public Works, and the New York State Water Resources Commission (formerly Water Power and Control Commission), 13 wells ranging in depth from about 130 to 800 feet were drilled during 1952 and 1953 and screened at various depths in the Magothy(?) formation and Jameco gravel. On the basis of the preliminary geologic, hydrologic, and chemical data from these wells, a detailed investigation of ground-water conditions from the water table to the bedrock was begun in a 200-square-mile area in southern Nassau and southeastern Queens Counties. The Inain purposes of the investigation were to delineate the bodies of fresh and salty ground water in the project area, to relate their occurrence and movement to geologic and hydrologic conditions, to estimate the rate of encroachment, if any, of the salty water, and to evaluate the effectiveness of the existing network of outpost wells as detectors of salt-water encroachment. About a million people in the report area, residing mainly in southern Nassau County, are completely dependent on ground water as a source of supply. Fortunately, precipitation averages about 44 inches per year, of which approximately half is estimated to percolate into the ground-water reservoir. The ground water is contained in and moves through eight differentiated geologic units composed of unconsolidated gravel, sand, and clay, of Late Cretaceous, Pleistocene, and Recent age, having a maximum total thickness of about 1,700 feet. The underlying metamorphic and igneous crystalline basement rocks are of Precambrian age and are not water bearing. The water-yielding units from the surface down are (1) the upper Pleistocene deposits, (2) the principal artesian aquifer, composed of the Jameco gravel and Magothy(?) formation, and (3) the Lloyd sand member of the Raritar formation. The confining units are the '20-foot' clay, the Gardiners clay, and the clay member of the Raritan formation. The upper Pleistocene deposits contain an extensive unconfined body of fresh water. Fresh water under artesian conditions is contained in the principal artesian aquifer and the Lloyd sand member. The piezometric surface of the principal artesian aquifer is similar in shape to the south-ward-sloping water table; it ranges in altitude from about sea level to 55 feet above. The chemical quality of the fresh ground water in most of the area in all aquifers is good to excellent, and concentrations of dissolved solids and of chloride generally are below 100 ppm (parts per million) and 10 ppm, respectively. Analyses of water samples from selected wells show no progressive increase in concentration of chloride in most of the area. The data on quality of water have been used to delineate one major and several minor bodies of salty ground water. The wedgeshaped main confined salt-water body, in which the concentration of chloride reaches about 17,000 ppm, is in the Magothy(?) formation and Jameco gravel in extreme southwestern Nassau County and southeastern Queens County. The base of the salt-water wedge is about at the top of the clay member of the Raritan formation. Beneath the barrier beach in south-central and southeastern Nassau County a shallow extension of the main confined salt-water body contains as much as 4,000 ppm of chloride and is separated from the lower main salt-water body by fresh ground water. Shallow, thin bodies of unconfined salty ground water are common in the upper Pleistocene and Recent deposits adjacent to salty surface water in tidal creeks, bays, and the Atlantic

New York↗
USGS1983

Analysis of the world distribution of metal-rich subsea manganese nodules

Publicly available data on the composition of subsea manganese nodules extend previous reports of differences in average metal contents from ocean to ocean and of variations related to latitude and depth. Pacific Ocean nodules have the highest average manganese, nickel, and copper contents, and Atlantic Ocean nodules have the highest average iron content. The average manganese, nickel, and copper contents generally increase toward the equator in both hemispheres, and iron content generally decreases. The variation of metal content with water depth is not linear; instead, there appears to be a threshold depth of about 2,900 to 3,000 m, above which combined nickel and copper contents are generally less than 1 percent and below which cobalt content is generally less than about 0.6 percent. The composition of the nodules varies widely, but three rarely overlapping types that are of possible economic interest can be recognized. (1) Nodules containing more than about 1 percent combined nickel and copper only exceptionally contain more than 0.5 percent cobalt and 35 percent manganese. (2) Nodules containing more than 0.5 percent cobalt rarely contain more than 1 percent combined nickel and copper and 35 percent manganese. (3) Nodules containing more than 35 percent manganese only exceptionally contain more than 0.5 percent cobalt, although they average nearly 1.1 percent combined nickel and copper. Current economic interest in nodule mining is focused on the Clarion-Clipperton zone in the northeastern equatorial Pacific Ocean, the largest known area in which nodules average 1.8 percent or more combined nickel and copper. Several other areas in which nodules are rich in these metals are found in the Pacific and Indian Oceans and may be viewed as targets for exploration. Nearly 60 chemical elements have been found in manganese nodules, many in concentrations far exceeding their crustal abundances. The amounts in which many minor elements are present vary with the amounts of principal metals present, but the three metal types described above do not include the maximum reported values for several other elements, such as titanium (8.9 percent), vanadium (0.5), zinc (9.0), and lead (0.75). It seems possible, therefore, that there may be other kinds of metal-rich types, some of which may have p6tential economic value. Many of the variations in nodule composition are in large part a function of variations in mineral composition, to which many factors contribute. Some of the regional variations can be broadly related to oceanic circulation, basin morphology, and depth, but a better understanding of ocean processes and regional oceanography and geology is needed to explain all the variations observed in the composition of manganese nodules.

Circular↗
USGS2004

The Collins Creek and Pleasant Creek Formations: Two new upper cretaceous subsurface units in the Carolina/Georgia Coastal Plain

This paper formally defines two new Upper Cretaceous subsurface units in the southern Atlantic Coastal Plain of North Carolina, South Carolina and Georgia: the Collins Creek Formation and the Pleasant Creek Formation. These units are confined to the subsurface of the outer Coastal Plain, and their type sections are established in corehole CHN-820 from Charleston County, S.C. The Collins Creek Formation consists of greenish-gray lignitic sand and dark-greenish-gray sandy clay and is documented in cores from Allendale, Beaufort, Berkeley, Dorchester, Jasper and Marion Counties, South Carolina, and from Screven County, Georgia. Previously, Collins Creek strata had been incorrectly assigned to the Middendorf Formation. These sediments occupy a stratigraphic position between the Turonian/Coniacian Cape Fear Formation (?) below and the proposed upper Coniacian to middle Santonian Pleasant Creek Formation above. The Collins Creek Formation is middle and late Coniacian in age on the basis of calcareous nannofossil and palynomorph analyses. The Pleasant Creek Formation consists of olive-gray sand and dark-greenish-gray silty to sandy clay and is documented in cores from New Hanover County, North Carolina, and Berkeley, Charleston, Dorchester, Horry and Marion Counties, South Carolina. The strata of this unit previously were assigned incorrectly to the Middendorf Formation and (or) the Cape Fear Formation. These sediments occupy a stratigraphic position between the proposed Collins Creek Formation below and the Shepherd Grove Formation above. The Pleasant Creek Formation is late Coniacian and middle Santonian in age, on the basis of its calcareous nannofossil and palynomorph assemblages.

Southeastern Geology↗
USGS1997

Sr-isotopic evidence for leakage of pore water from clay-silt confining units to the Atlantic City 800-foot sand, Atlantic City, New Jersey

The evolution of water quality in confined aquifers in the New Jersey Coastal Plain may be affected by leakage of pore water from the adjacent confining units. We investigated the distribution and sources of solutes, particularly Sr, in pore water mechanically extracted from clay-silt core samples collected from depths of 552–840 ft (168–256 m) in the lower Miocene Kirkwood Formation at Atlantic City, New Jersey (Ocean Drilling Program Leg 150X). The sampled sediments consist of thin clay-silt stringers in the upper part of the Atlantic City 800-ft sand, a major aquifer, and the massive clay-silt units above and below it. The distribution of Sr and the ratio of 87 Sr to 86 Sr in the pore water and adjacent shell material were used to identify the possible sources of, and physical processes that may affect the distribution of, Sr in the pore water. Concentrations of Sr in 14 pore-water samples from the clay-silt unit above the aquifer and the clay-silt interbeds in the upper part of the aquifer ranged from 2.74 to 28.19 µM/L; those in the four pore-water samples from the clay-silt unit below the aquifer ranged from 0.52 to 7.30 µM/L. Concentrations of Sr in the samples varied with depth but correlated strongly with pore-water concentrations of Ca, Mg, Na, and SO4. Cation-exchange processes may be responsible, in part, for the lower concentrations of Sr, Ca, and Mg in pore water from the clay-silt unit below the aquifer than in that above the aquifer. 87 Sr/ 86 Sr values in 11 samples of aragonitic mollusk shells (bearing no visible evidence of recrystallization) collected from depths in the clay-silt unit similar to those from which the pore-water samples were collected ranged from 0.708468 to 0.708713 , and decreased (Sr in the shells was less radiogenic) with depth. This trend is consistent with the decrease in the 87 Sr/ 86 Sr value in seawater through time during the early Miocene. The 87 Sr/ 86 Sr values in 12 pore-water samples from the studied stratigraphic interval ranged from 0.708257 to 0.708527 and also decreased with depth. The Sr-isotope ratios in the pore water were lower than those in the shell material from nearby or adjacent sediments for all samples but one. Because the only known source of Sr with an isotope ratio this low is shell material from sediments deeper than the strata from which the pore-water samples were collected (including pre-Miocene stratigraphic units), the isotope ratio in the pore-water samples from the lower Miocene claysilt units may result from upward movement of pore water into lower Miocene strata through geologic time, which could create the observed difference in Sr isotope ratios between the pore water and shells.

New Jersey↗
USGS2008

Simulation of the Quantity, Variability, and Timing of Streamflow in the Dennys River Basin, Maine, by Use of a Precipitation-Runoff Watershed Model

The U.S. Geological Survey (USGS), in cooperation with the Maine Department of Marine Resources Bureau of Sea Run Fisheries and Habitat, began a study in 2004 to characterize the quantity, variability, and timing of streamflow in the Dennys River. The study included a synoptic summary of historical streamflow data at a long-term streamflow gage, collecting data from an additional four short-term streamflow gages, and the development and evaluation of a distributed-parameter watershed model for the Dennys River Basin. The watershed model used in this investigation was the USGS Precipitation-Runoff Modeling System (PRMS). The Geographic Information System (GIS) Weasel was used to delineate the Dennys River Basin and subbasins and derive parameters for their physical geographic features. Calibration of the models used in this investigation involved a four-step procedure in which model output was evaluated against four calibration data sets using computed objective functions for solar radiation, potential evapotranspiration, annual and seasonal water budgets, and daily streamflows. The calibration procedure involved thousands of model runs and was carried out using the USGS software application Luca (Let us calibrate). Luca uses the Shuffled Complex Evolution (SCE) global search algorithm to calibrate the model parameters. The SCE method reliably produces satisfactory solutions for large, complex optimization problems. The primary calibration effort went into the Dennys main stem watershed model. Calibrated parameter values obtained for the Dennys main stem model were transferred to the Cathance Stream model, and a similar four-step SCE calibration procedure was performed; this effort was undertaken to determine the potential to transfer modeling information to a nearby basin in the same region. The calibrated Dennys main stem watershed model performed with Nash-Sutcliffe efficiency (NSE) statistic values for the calibration period and evaluation period of 0.79 and 0.76, respectively. The Cathance Stream model had an NSE value of 0.68. The Dennys River Basin models make use of limited streamflow-gaging station data and provide information to characterize subbasin hydrology. The calibrated PRMS watershed models of the Dennys River Basin provide simulated daily streamflow time series from October 1, 1985, through September 30, 2006, for nearly any location within the basin. These models enable natural-resources managers to characterize the timing and quantity of water moving through the basin to support many endeavors including geochemical calculations, water-use assessment, Atlantic salmon population dynamics and migration modeling, habitat modeling and assessment, and other resource-management scenario evaluations. Characterizing streamflow contributions from subbasins in the basin and the relative amounts of surface- and ground-water contributions to streamflow throughout the basin will lead to a better understanding of water quantity and quality in the basin. Improved water-resources information will support Atlantic salmon protection efforts.

Scientific Investigations Report↗
USGS1991

Rise and demise of the Bahama-Grand Banks gigaplatform, northern margin of the Jurassic proto-Atlantic seaway

An extinct, > 5000-km-long Jurassic carbonate platform and barrier reef system lies buried beneath the Atlantic continental shelf and slope of the United States. A revised stratigraphic framework, a series of regional isopach maps, and paleogeographic reconstructions are used to illustrate the 42-m.y. history of this Bahama-Grand Banks gigaplatform from its inception in Aalenian(?) (early Middle Jurassic) time to its demise and burial in Berriasian-Valanginian time (early Early Cretaceous). Aggradation-progradation rates for the gigaplatform are comparable to those of the familiar Capitan shelf margin (Permian) and are closely correlated with volumetric rates of siliciclastic sediment accumulation and depocenter migration. Siliciclastic encroachment behind the carbonate tracts appears to have been an important impetus for shelf-edge progradation. During the Early Cretaceous, sea-level changes combined with eutrophication (due to landward soil development and seaward upwelling) and the presence of cooler upwelled waters along the outer shelf appear to have decimated the carbonate producers from the Carolina Trough to the Grand Banks. This allowed advancing siliciclastic deltas to overrun the shelf edge despite a notable reduction in siliciclastic accumulation rates. However, upwelling did not extend southward to the Blake-Bahama megabank, so platform carbonate production proceeded there well into the Cretaceous. Subsequent stepwise carbonate abatement characterized the Blake Plateau Basin, whereas the Bahamas have maintained production to the present. The demise of carbonate production on the northern segments of the gigaplatform helped to escalate deep-water carbonate deposition in the Early Cretaceous, but the sudden augmentation of deep-water carbonate reservoirs in the Late Jurassic was triggered by other agents, such as global expansion of nannoplankton communities.

Marine Geology↗
USGS2010

An initial SPARROW model of land use and in-stream controls on total organic carbon in streams of the conterminous United States

Watersheds play many important roles in the carbon cycle: (1) they are a site for both terrestrial and aquatic carbon dioxide (CO2) removal through photosynthesis; (2) they transport living and decomposing organic carbon in streams and groundwater; and (3) they store organic carbon for widely varying lengths of time as a function of many biogeochemical factors. Using the U.S. Geological Survey (USGS) Spatially Referenced Regression on Watershed Attributes (SPARROW) model, along with long-term monitoring data on total organic carbon (TOC), this research quantitatively estimates the sources, transport, and fate of the long-term mean annual load of TOC in streams of the conterminous United States. The model simulations use surrogate measures of the major terrestrial and aquatic sources of organic carbon to estimate the long-term mean annual load of TOC in streams. The estimated carbon sources in the model are associated with four land uses (urban, cultivated, forest, and wetlands) and autochthonous fixation of carbon (stream photosynthesis). Stream photosynthesis is determined by reach-level application of an empirical model of stream chlorophyll based on total phosphorus concentration, and a mechanistic model of photosynthetic rate based on chlorophyll, average daily solar irradiance, water column light attenuation, and reach dimensions. It was found that the estimate of in-stream photosynthesis is a major contributor to the mean annual TOC load per unit of drainage area (that is, yield) in large streams, with a median share of about 60 percent of the total mean annual carbon load in streams with mean flows above 500 cubic feet per second. The interquartile range of the model predictions of TOC from in-stream photosynthesis is from 0.1 to 0.4 grams (g) carbon (C) per square meter (m-2) per day (day-1) for the approximately 62,000 stream reaches in the continental United States, which compares favorably with the reported literature range for net carbon fixation by phytoplankton in lakes and streams. The largest contributors per unit of drainage area to the mean annual stream TOC load among the terrestrial sources are, in descending order: wetlands, urban lands, mixed forests, agricultural lands, evergreen forests, and deciduous forests . It was found that the SPARROW model estimates of TOC contributions to streams associated with these land uses are also consistent with literature estimates. SPARROW model calibration results are used to simulate the delivery of TOC loads to the coastal areas of seven major regional drainages. It was found that stream photosynthesis is the largest source of the TOC yields ( about 50 percent) delivered to the coastal waters in two of the seven regional drainages (the Pacific Northwest and Mississippi-Atchafalaya-Red River basins ), whereas terrestrial sources are dominant (greater than 60 percent) in all other regions (North Atlantic, South Atlantic-Gulf, California, Texas-Gulf, and Great Lakes).

Conterminous United States↗