Geology topics

Wolfgang V. Swarzenski

Publications and source records attributed to Wolfgang V. Swarzenski.

2 recordsLinked to original sources

USGS1966

Salt-water encroachment in southern Nassau and southeastern Queens Counties, Long Island, New York

Test drilling, extraction of water from cores, electric logging, water sampling, and water-level measurements from 1958 to 1961 provided a suitable basis for a substantial refinement in the definition of the positions, chloride concentrations, and rates of movement of salty water in the intermediate and deep deposits of southern Nassau County and southeastern Queens County. Filter-press, centrifugal, and dilution methods were used to extract water from cores for chloride analysis at the test-drilling sites. Chloride analysis of water extracted by these methods, chloride analyses of water from wells, and the interpretation of electric logs helped to define the chloride content of the salty water. New concepts of environmental-water head and zerovels, developed during the investigation, proved useful for defining hydraulic gradients and ratee of flow in ground water of variable density in a vertical direction and in horizontal and inclined planes, respectively. Hydraulic gradients in and between fresh and salty water were determined from water levels from data at individual and multiple-observation wells. Salty ground water occurs in southern Nassau and southeastern Queens Counties as three wedgelike extensions that project landward in unconsolidated deposits from a main body of salty water that lies seaward of the barrier beaches in Nassau County and of Jamaica Bay in Queens County. Salty water occurs not only in permeable deposits but also in the shallow and deep clay deposits. The highest chloride content of the salty ground water in the main body and the wedges is about 16,000 ppm, which is about 1,000 to 2,000 ppm less than the chloride content of ocean water. The shallow salty water in the Pleistocene and Recent deposits is connected freely with the bays, tidal estuaries, and ocean. The intermediate wedge is found only in the southwestern part of Nassau County in the upper part of the Magothy (?) Formation, in the Jamneco Gravel, and in the overlying clay deposits. It extends from the seaward areas inland about 2 miles into Island Park. The deep wedge extends into southeastern Queens County and southern Nassau County principally in the deeper parts of the Magothy (?) Formation and in the underlying clay member of the Raritan Formation. The leading edge of the deep wedge is at the base of the Magothy (?) Formation. This edge is apparently at the shoreline east of Lido Beach and extends inland about 4 miles to Woodmere and about 7 miles to South Ozone Park. Zones of diffusion as much as 6 miles wide and about 500 feet thick were delineated in the frontal part of the salty-water wedges. These thick and broad zones of diffusion were probably formed during the past 1,000 or more years in heterogeneous unconsolidated deposits by long- and short-term changes in sea level and in fresh-water outflow to the sea and by dispersion caused by the movements of the water and its salt mass. Changes in sea level and fresh-water outflow together produced appreciable advances and recessions of the salt-water front. The chemical compositions of the diffused water in all wedges are modified to some extent by base exchange and other physical and chemical processes and also by diffusion. The intermediate wedge of salty water is moving landward at a rate of less than 20 feet a year in the vicinity of Island Park and, thus, has moved less than 1,000 feet since 1900. The leading edge of the deep wedge has advanced landward at about 300 feet a :ear in Woodmere in southwestern Nassau County and about 160 feet a year at South Ozone Park in southeastern Queens County, principally under the influence of local withdrawals near the toe of the wedge. Between Hewlett and Lido Beach, the deep wedge is moving inland at the rate of about 10 feet a year under the influence of regional withdrawals in inland areas. Regional encroachment of the deep wedge is apparently retarded appreciably by cyclic flow, that is, by the return seaward in the upper

Water Supply Paper↗

USGS1964

Hydrogeology of northwestern Nassau and northeastern Queens Counties, Long Island, New York

A detailed investigation of the geology and ground-water occurrence in northwestern Nassau and northeastern Queens Counties, N.Y., has been completed by the U.S. Geological Survey, in cooperation with the Nassau County Department of Public Works and the New York State Water Resources Commission. The area, about 63 square miles, includes the peninsulas of Great Neck and Manhasset Neck and the western part of Nassau County as far south as Garden City. Unconsolidated sediments of Pleistocene and Cretaceous aged 200 to 800 feet thick, constitute the ground-water reservoir of the area. The reservoir includes three discrete aquifers, not all found in the same locality, which transect geologic boundaries. The shallow unconfined aquifer consists of those permeable Pleistocene and Cretaceous deposits that lie within the upper part of the zone of saturation, which extends from slightly below sea level to more than 110 feet above sea level. It is an abundant source of water in much of the area, particularly in the southern part, where the aquifer consists of coarse sand and gravel in a glacial-outwash plain. The intermediate or principal aquifer consists largely of that part of the Magothy(?) formation that occurs from about 50 feet below sea level downward to the top of the clay member of the Raritan formation. Locally, however, the aquifer includes Pleistocene deposits which blanket the Magothy(?) formation or lie in channels cut into it. Although the principal aquifer has limited extent to the north, it is the chief source of water in most of the area, except the peninsulas. The lower or deep confined aquifer is found beneath the entire project area, and consists of the Lloyd sand member of the Raritan formation and the hydraulically contiguous Jameco gravel. The lower limit of the aquifer is the bedrock surface; its upper limit is defined by the overlying clay member of the Raritan formation and the Gardiners clay, the latter abutting against the clay member on the north or, in some valleys and embankments, lying directly upon the clay member. Thus, hydraulic continuity exists between the Lloyd sand member of the Raritan formation (Cretaceous) and the Jameco gravel (Pleistocene) in the northern part of Manhasset and Great Necks. The two contiguous clay bodies overlying the aquifer, the clay member of the Raritan formation and the Gardiners clay, form an effective confining bed which probably extends beyond the shore lines of the project area. The deep confined aquifer is particularly important on Manhasset and Great Necks where locally it is the only source of water available for large public-supply or industrial needs. In general, ground-water supplies in sufficient quantity and of excellent quality can be obtained from the three aquifers underlying northwestern Nassau and northeastern Queens Counties, N.Y. Ground-water withdrawals for public supply have increased with population growth and expanded use from an average of about 10 millions of gallons per day in 1940 to 30 mgd in 1957. In addition, about 10 mgd are pumped for various industrial, institutional and private uses. Much of the water pumped by industry is returned to the ground by diffusion wells and recharge basins. However, an increasing amount of water is lost from the ground-water reservoir due to the expanding network of server systems discharging directly to the sea. In the Manhasset Neck and Great Neck areas, ground-water resources are approaching full development in terms of the total available supply, if such development has not been reached already (1959). The chief limiting factor to further expansion lies in the geometry of the aquifers and the reduced thickness of permeable saturated sediments. In the northern part of both peninsulas, the ground-water reservoir is only about 200 to 400 feet thick, and, locally, as much as 75 percent of the strata in the reservoir consists of rather impermeable silt and clay of the Raritan formation or the Gardiners clay. I

Water Supply Paper↗