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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 847 records · Page 47Linked to original sources

USGS2023

Application of geophysical methods to enhance aquifer characterization and groundwater-flow model development, Des Moines River alluvial aquifer, Des Moines, Iowa, 2022

Des Moines Water Works (DMWW) is one of the largest water providers in Iowa and as population growth continues, demand for drinking water is increasing. DMWW uses groundwater and surface water as raw water sources to supply the City of Des Moines and surrounding communities. In response to current and future demands, DMWW is in need of a thorough understanding of local groundwater resources, specifically the Des Moines River alluvial aquifer. The Des Moines River alluvial aquifer is hydraulically connected to the Des Moines River and consists of alluvial deposits and glacial outwash sands and gravels. To ensure a sustainable groundwater supply, additional information to better understand and manage groundwater availability within the Des Moines River alluvial aquifer would be beneficial. Beginning in 2018, DMWW partnered with the U.S. Geological Survey to construct a groundwater-flow model to increase understanding of the hydrologic system in the Des Moines area. The model hydrogeologic framework will be enhanced by using multiple geophysical methods of data collection in the Des Moines River, Beaver Creek, and the Des Moines River alluvial aquifer that could provide a better understanding of the geology in the model area.

Iowa↗

USGS2010

Geophysical Logs, Specific Capacity, and Water Quality of Four Wells at Rogers Mechanical (former Tate Andale) Property, North Penn Area 6 Superfund Site, Lansdale, Pennsylvania, 2006-07

As part of technical assistance to the U.S. Environmental Protection Agency (USEPA) in the remediation of properties on the North Penn Area 6 Superfund Site in Lansdale, Pa., the U.S. Geological Survey (USGS) in 2006-07 collected data in four monitor wells at the Rogers Mechanical (former Tate Andale) property. During this period, USGS collected and analyzed borehole geophysical and video logs of three new monitor wells (Rogers 4, Rogers 5, and Rogers 6) ranging in depth from 80 to 180 feet, a borehole video log and additional heatpulse-flowmeter measurements (to quantify vertical borehole flow) in one existing 100-foot deep well (Rogers 3S), and water-level data during development of two wells (Rogers 5 and Rogers 6) to determine specific capacity. USGS also summarized results of passive-diffusion bag sampling for volatile organic compounds (VOCs) in the four wells. These data were intended to help understand the groundwater system and the distribution of VOC contaminants in groundwater at the property.

Open-File Report↗

USGS2013

Holocene sediment distribution on the inner continental shelf of northeastern South Carolina: implications for the regional sediment budget and long-term shoreline response

High-resolution geophysical and sediment sampling surveys were conducted offshore of the Grand Strand, South Carolina to define the shallow geologic framework of the inner shelf. Results are used to identify and map Holocene sediment deposits, infer sediment transport pathways, and discuss implications for the regional coastal sediment budget. The thickest deposits of Holocene sediment observed on the inner shelf form shoal complexes composed of moderately sorted fine sand, which are primarily located offshore of modern tidal inlets. These shoal deposits contain ~67 M m 3 of sediment, approximately 96% of Holocene sediment stored on the inner shelf. Due to the lack of any significant modern fluvial input of sand to the region, the Holocene deposits are likely derived from reworking of relict Pleistocene and older inner-shelf deposits during the Holocene marine transgression. The Holocene sediments are concentrated in the southern part of the study area, due to a combination of ancestral drainage patterns, a regional shift in sediment supply from the northeast to the southwest in the late Pleistocene, and proximity to modern inlet systems. Where sediment is limited, only small, low relief ridges have formed and Pleistocene and older deposits are exposed on the seafloor. The low-relief ridges are likely the result of a thin, mobile veneer of sediment being transported across an irregular, erosional surface formed during the last transgression. Sediment textural trends and seafloor morphology indicate a long-term net transport of sediment to the southwest. This is supported by oceanographic studies that suggest the long-term sediment transport direction is controlled by the frequency and intensity of storms that pass through the region, where low pressure systems yield net along-shore flow to the southwest and a weak onshore component. Current sediment budget estimates for the Grand Strand yield a deficit for the region. Volume calculations of Holocene deposits on the inner shelf suggest that there is sufficient sediment to balance the sediment budget and provide a source of sediment to the shoreline. Although the processes controlling cross-shelf sediment transport are not fully understood, in sediment-limited environments such as the Grand Strand, erosion of the inner shelf likely contributes significant sediment to the beach system.

South Carolina↗

USGS2012

USGS advances in integrated, high-resolution sea-floor mapping: inner continental shelf to estuaries

The U.S. Geological Survey (USGS) has been involved in geological mapping of the sea floor for the past thirty years. Early geophysical and acoustic mapping efforts using GLORIA (Geologic LOng Range Inclined ASDIC) a long-range sidescan-sonar system, provided broad-scale imagery of deep waters within the U.S. Exclusive Economic Zone (EEZ). In the early 1990's, research emphasis shifted from deep- to shallow-water environments to address pertinent coastal research and resource management issues. Use of shallow-water, high-resolution geophysical systems has enhanced our understanding of the processes shaping shallow marine environments. However, research within these shallow-water environments continues to present technological challenges.

Conference Paper↗

USGS2006

Modeling and validation of a 3D velocity structure for the Santa Clara Valley, California, for seismic-wave simulations

A 3D seismic velocity and attenuation model is developed for Santa Clara Valley, California, and its surrounding uplands to predict ground motions from scenario earthquakes. The model is developed using a variety of geologic and geophysical data. Our starting point is a 3D geologic model developed primarily from geologic mapping and gravity and magnetic surveys. An initial velocity model is constructed by using seismic velocities from boreholes, reflection/refraction lines, and spatial autocorrelation microtremor surveys. This model is further refined and the seismic attenuation is estimated through waveform modeling of weak motions from small local events and strong-ground motion from the 1989 Loma Prieta earthquake. Waveforms are calculated to an upper frequency of 1 Hz using a parallelized finite-difference code that utilizes two regions with a factor of 3 difference in grid spacing to reduce memory requirements. Cenozoic basins trap and strongly amplify ground motions. This effect is particularly strong in the Evergreen Basin on the northeastern side of the Santa Clara Valley, where the steeply dipping Silver Creek fault forms the southwestern boundary of the basin. In comparison, the Cupertino Basin on the southwestern side of the valley has a more moderate response, which is attributed to a greater age and velocity of the Cenozoic fill. Surface waves play a major role in the ground motion of sedimentary basins, and they are seen to strongly develop along the western margins of the Santa Clara Valley for our simulation of the Loma Prieta earthquake.

California↗

USGS1980

High-resolution seismic-reflection profiling data from the inner continental shelf of southeastern Massachusetts

Six hundred-seventy kilometers of closely spaced high-resolution seismic-reflection data have been collected from eastern Rhode Island Sound and Vineyard Sound, Mass, by the U.S. Geological Survey in cooperation with the Massachusetts Department of Public Works. These data were obtained during the June 1975 cruise of the R/V ASTERIAS as part of a continuing regional study of the Massachusetts offshore area to assess potential mineral resources, to evaluate environmental impact of mining of resources and of offshore disposal of solid waste and harbor dredge-spoil materials, and to map the offshore geology and shallow structure. The data were obtained by using a surface-towed EG&G Unit Pulse Boomer* (300 joules: 400 Hz-8kHz frequency) sound source. Reflected acoustic energy was detected by a 4.6-m, a-element hydrophone array, was amplified, was actively filtered (400 Hz-4kHz bandpass), and was graphically displayed on an EPC* dry paper recorder at a 0.25-second sweep rate. System resolution was generally 1 to 1.5 m. Navigational control was provided by Loran C (positional accuracy within 0.2 km) and was supplemented by radar and visual fixes. Positional information was logged at 15-minute intervals and at major course changes. The original records may be examined at the Data Library, U.S. Geological Survey, Woods Hole, MA 02543. Microfilm copies of the data are available for purchase from the National Geophysical and Solar-Terrestrial Data Center (NGSDC), Boulder, CO 80302.

Open-File Report↗

USGS1980

Side-scan sonograph data from eastern Rhode Island Sound and Vineyard Sound, Massachusetts

Two hundred twenty-four kilometers of closely spaced side-scan sonograph data have been collected from eastern Rhode Island Sound and Vineyard Sound, Mass., by the U.S. Geological Survey in cooperation with the New England Division of the U.S. Army Corps of Engineers. These data were obtained during the August 1976 cruise of the B./V A. E. VERRILL as part of a continuing regional study of the Massachusetts offshore area to determine the suitability and potential environmental effect of ocean dumping of large volumes of harbor dredge-spoil material. Specifically, as part of a proposed Federal Harbor improvement and maintenance dredging of Fall River and Mt. Hope Bay, Mass. under the jurisdiction of the Army Corps of Engineers, the disposal of the resultant dredge spoil is planned for an ocean dump site located in eastern Rhode Island Sound. The proposed site is also under consideration as a "regional" disposal grounds to be utilized by State and private organizations performing dredging work authorized by the Corps. The data were obtained by using a Klein Side Scan Towfish* (sonar frequency, 100 kHz; pulse length, 0.1 msec). Signal returns from the starboard and port scans were automatically tuned, texture-enhanced, and printed centerout on 2 channels of a 3-channel Klein* wet-paper graphic recorder. Scan ranges of 75 m and 150 m were used. For comparison of graphic display, incoming signals from the starboard scan were also recorded on the third channel using a manual (nonautomatic) tuning mode. Navigational control was provided by Loran -C (positional accuracy within 0.2 km). Positional information was logged at 15-minute intervals and at major course changes. The original records may be examined at the Data Library, U.S. Geological Survey, Woods Hole, MA 02543. Microfilm copies of the data are available for purchase from the National Geophysical and Solar-Terrestrial Data Center (NGSDC), Boulder, CO 80302.

Open-File Report↗

USGS1980

Single-channel seismic-reflection profiles from Massachusetts coastal waters and the western part of Georges Bank

The U.S. Geological Survey collected approximately 1,200 km each of airgun and minisparker single-channel seismic-reflection profiles during the R/V FAY cruise 023 in September 1976. The purpose of the 6-day cruise was to study the shallow sedimentary structure south and east of southern Massachusetts and to obtain magnetic and gravity data in these areas and in the vicinity of Great South Channel and Cape Ann. The survey was conducted by the U.S. Geological Survey as part of the Massachusetts Cooperative Marine Geologic Program. Seismic instruments used include a 1 Teledyne 600-joule minisparker system and a 20-in 3 airgun system. Navigational data during the cruise were obtained by the use of an Integrated Navigation System, which included the following subsystems: Teledyne Loran-C for both range-range and hyperbofic positions; Magnovox s'atellite receiver; Sperry Mark-29 gyrocompass; and Hewlett-Packard 21 MX computer system with dual 9-track magnetic tape recording. The original records may be studied at the U.S. Geological Survey offices in Woods Hole, Mass. Copies of the records can be purchased only from the National Geophysical and Solar-Terrestrial Data Center, NOAA/EDIS/NGSDC, Code D621, 325 Broadway, Boulder CO 80303- (303-497-6338).

Open-File Report↗

USGS1981

Sidescan-sonar data collected during May 1978 from the southern New England continental shelf

Sidescan-sonar data were collected aboard R/V WESTWARD (Cruise W-39-4) during May 1978 by the U.S. Geological Survey using an Ocean Research Equipment System. Navigation in the study area was by Loran C. The 368 kilometers of survey were conducted in Block Island Sound, in Rhode Island Sound, and over the mid-Continental Shelf south of Block Island and Martha's Vineyard. Although the records are generally of good quality, variable ship speeds were caused by changes of wind and sail. Thus, care must be used in dimensional and orientation analysis of the bed-form features observed on the records. On the midshelf, three bottom types were observed: 1) smooth, featureless sea floor, 2) elongated bodies of megaripples, and 3) ground-fishing trawler marks. The distribution of the .features seems to be related to current velocity, grain-size distribution, water depth, and fishing intensity. The midshelf survey results are discussed with cruise data of R/V CAPE HENLOPEN (also collected in the spring of 1978) \ by Twichell and others. The sonographs from Block Island and Rhode Island Sounds show a pattern indicative of a till cap atop a submerged part of the coastal end moraine, as well as the megarippled and smooth sea floor. The original records may be examined in the U.S. Geological Survey offices in Woods Hole, Mass. Copies of the records can be purchased only from the National Geophysical and Solar-Terrestrial Data Center, NOAA/EDIS/NGSDC, Code D621 , 325 Broadway, Boulder, CO 80303 (303-497-6338).

Open-File Report↗

USGS1981

High-resolution seismic-reflection profiles from the Duxbury, Massachusetts, area

In August 1980, The U.S. Geological Survey conducted a seismic study (fig. 1) of the harbor and nearshore waters of Duxbury, Massachusetts, aboard the 38' research vessel R/V NEECHO. In all, 18.5 kilometers of high-resolution seismic profiles and sidescan-sonar data were obtained. The systems used included an 80-J minisparker and an EPC-32001 recorder and an EDO Western sidescan system. The navigation was by Northstar LORAN-C and by buoy-to-buoy dead reckoning within Duxbury Harbor. The original records may be viewed at the U.S. Geological Survey, Woods Hole, Massachusetts. Microfilm copies of the seismic profiles can be purchased only from the National Geophysical and Solar-Terrestrial Data Center, U.S. National Oceanic and Atmospheric Administration, NOAA/EDIS/NGSDC, 325 Broadway, Code D621, Boulder, Colorado 80303.

Massachusetts↗

USGS2015

Delineation of areas having elevated electrical conductivity, orientation and characterization of bedrock fractures, and occurrence of groundwater discharge to surface water at the U.S. Environmental Protection Agency Barite Hill/Nevada Goldfields Superfund site near McCormick, South Carolina

During October 2012 through March 2013, the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency (EPA) Region 4, Superfund Section, conducted borehole geophysical logging, surface geophysical surveys, and water-quality profiling in selected wells and areas to characterize or delineate the extent of elevated subsurface electrical conductivity at the EPA Barite Hill/Nevada Goldfields Superfund site near McCormick, South Carolina. Elevated electrical conductivity measured at the site may be related to native rock materials, waste rock disposal areas used in past operations, and (or) groundwater having elevated dissolved solids (primarily metals and major ions) related to waste migration. Five shallow screened wells and four open-borehole bedrock wells were logged by using a suite of borehole tools, and downhole water-quality profiles were recorded in two additional wells. Well depths ranged from about 26 to 300 feet below land surface. Surface geophysical surveys based on frequency-domain electromagnetic and distributed temperature sensing (DTS) techniques were used to identify areas of elevated electrical conductivity (Earth materials and groundwater) and potential high dissolved solids in groundwater and surface water on land and in areas along the northern unnamed tributary at the site. Results from the electromagnetic-induction logging of four selected wells near the Main Pit and one well located about 800 feet southeast of the Main Pit lake indicate that elevated electrical conductivity extends to a depth of about 110 feet below land surface. Groundwater-quality properties recorded in eight selected wells were highly variable, suggesting a broad spectrum of geochemical conditions and contaminant concentrations within the groundwater system. Ranges of field water-quality properties recorded from water-profiling of groundwater in all wells logged were as follows: pH, 3.1 to 9.2; specific conductance, 48 to 5,300 microsiemens per centimeter; dissolved oxygen, 0.2 to 4.4 milligrams per liter; and water temperature, 17.0 to 18.0 degrees Celsius. The highest specific conductance and lowest pH measurements were made in boreholes located between the Main Pit lake and the northern unnamed tributary. Conceptually, these wells may intercept elevated dissolved solids in groundwater leaking from the Main Pit lake along a flow path that discharges into the unnamed tributary to the north. Results from surface geophysical electromagnetic and fiber-optics surveys confirm areas of focused discharge of groundwater near the Main Pit lake along the northern unnamed tributary. The frequency-domain surface electromagnetic surveys also identified an area with higher levels of elevated electrical conductivity located northwest of the former Rainsford Pit area. Bedrock properties were characterized from borehole geophysical logs collected from three open-borehole bedrock wells. The mean strike azimuth of the borehole foliation data measured in bedrock well IR-1 was 221° (N. 41° E.), and the mean dip angle was 78° to the northwest. Dominant strike azimuth orientations of primary fractures measured in three boreholes were from 210° to 250° (N. 30° E. to N. 70° E.) with a mean dip of 68° northwest. Transmissivity estimates interpreted from the heat-pulse flowmeter data from bedrock well IR-1 were about 69 feet squared per day, and the radius of influence was estimated at about 640 feet.

South Carolina↗

USGS1983

Map showing outcrops of basaltic rocks of early Quaternary and Tertiary age, Basin and Range province, Southern California

This map report is one of a series of geologic and hydrologic maps covering all or parts of States within the Basin and Range province of the western United States. The map reports contain detailed information on subjects that characterize the geohydrology of the province, including the ground-water hydrology/ ground-water quality, surface distribution of selected rock types, tectonic conditions, areal geophysics, Pleistocene lakes and marshes, and mineral and energy resources. This is a part of the U.S. Geological Survey's program for geologic and hydrologic evaluation of the province to identify prospective regions for further study relative to isolation of high-level nuclear waste (Bedinger, Sargent, and Reed, 1984). This map was prepared from published geologic maps and reports utilizing the project guidelines defined in Sargent and Bedinger (1984). As used in this study, basaltic rocks include basaltic andesite and basalt. The map shows the known occurrences of basaltic rocks largely of Tertiary age. Locally, however, where basalts of Quaternary age were not differentiated from those of Tertiary age, the younger basalts have been included on the map. The Description of Map Units includes the geologic and, if available, radiometric age; lithology; thickness where available; and sources of data for the basaltic units in outlined and numbered areas within the counties of the study area. No information was available on the rock outcrops that are unnumbered. The listed radiometric ages do not necessarily represent the entire age range of a unit.

California↗

USGS1996

Time-dependent Data System (TDDS); an interactive program to assemble, manage, and appraise input data and numerical output of flow/transport simulation models

A system of functional utilities and computer routines, collectively identified as the Time-Dependent Data System CI DDS), has been developed and documented by the U.S. Geological Survey. The TDDS is designed for processing time sequences of discrete, fixed-interval, time-varying geophysical data--in particular, hydrologic data. Such data include various, dependent variables and related parameters typically needed as input for execution of one-, two-, and three-dimensional hydrodynamic/transport and associated water-quality simulation models. Such data can also include time sequences of results generated by numerical simulation models. Specifically, TDDS provides the functional capabilities to process, store, retrieve, and compile data in a Time-Dependent Data Base (TDDB) in response to interactive user commands or pre-programmed directives. Thus, the TDDS, in conjunction with a companion TDDB, provides a ready means for processing, preparation, and assembly of time sequences of data for input to models; collection, categorization, and storage of simulation results from models; and intercomparison of field data and simulation results. The TDDS can be used to edit and verify prototype, time-dependent data to affirm that selected sequences of data are accurate, contiguous, and appropriate for numerical simulation modeling. It can be used to prepare time-varying data in a variety of formats, such as tabular lists, sequential files, arrays, graphical displays, as well as line-printer plots of single or multiparameter data sets. The TDDB is organized and maintained as a direct-access data base by the TDDS, thus providing simple, yet efficient, data management and access. A single, easily used, program interface that provides all access to and from a particular TDDB is available for use directly within models, other user-provided programs, and other data systems. This interface, together with each major functional utility of the TDDS, is described and documented in this report.

Water-Resources Investigations Report↗

USGS2010

Spatial Databases of Geological, Geophysical, and Mineral Resource Data Relevant to Sandstone-Hosted Copper Deposits in Central Kazakhstan

Central Kazakhstan is host to one of the world's giant sandstone-hosted copper deposits, the Dzhezkazgan deposit, and several similar, smaller deposits. The United Stated Geological Survey (USGS) is assessing the potential for other, undiscovered deposits of this type in the surrounding region of central Kazakhstan. As part of this effort, Syusyura compiled and partially translated an array of mostly unpublished geologic, geophysical, and mineral resource data for this region in digital format from the archives of the former Union of Soviet Socialists Republics (of which Kazakhstan was one of the member republics until its dissolution in 1991), as well as from later archives of the Republic of Kazakhstan or of the Kazakhstan consulting firm Mining Economic Consulting (MEC). These digital data are primarily map-based displays of information that were transmitted either in ESRI ArcGIS, georeferenced format, or non-georeferenced map image files. Box and Wallis reviewed all the data, translated Cyrillic text where necessary, inspected the maps for consistency, georeferenced the unprojected map images, and reorganized the data into the filename and folder structure of this publication.

Open-File Report↗

USGS1986

Identifying hydraulically conductive fractures with a slow-velocity borehole flowmeter

The U.S. Geological Survey used a recently developed heat-pulse flowmeter to measure very slow borehole axial water velocities in granitic rock at a site near Lac du Bonnet, Manitoba, Canada. The flowmeter was used with other geophysical measurements to locate and identify hydraulically conducting fractures contributing to the very slow vertical water flow in the two boreholes selected for study. The heat-pulse flowmeter has no moving parts and operates on the tag–trace principle. It is an improved version of the flowmeter developed by the Water Research Centre in England in 1975. The U.S. Geological Survey's heat-pulse flowmeter has a flow-measuring range in water of 0.06–6 m/min, and can resolve velocity differences as slow as 0.01 m/min. This is an order of magnitude slower than the stall speed of spinner flowmeters. The flowmeter is 1.16 m long and 44 mm in diameter. It was calibrated in columns of 76 and 152 mm diameter, to correspond to the boreholes studied. The heat-pulse flowmeter system is evaluated, and problems peculiar to the measurement of very slow axial water velocities in boreholes are discussed. Key words : flowmeter, borehole flow, low flow, borehole geophysics.

Manitoba↗

USGS1988

Subsurface geology of Paleozoic, Mesozoic, and Cenozoic units in southeast Missouri

The U.S. Geological Survey is conducting a regional water-resources investigation of the Gulf Costal Plain, which includes all of the Mississippi Alluvial Plain of southeastern Missouri, locally known as the southeast lowlands. The purpose of the regional study is to describe and evaluate the major aquifer systems in sediments of Tertiary and younger age in parts of 10 states (Grubb, 1984). In the southeast lowlands of Missouri, the sub-surface stratigraphy and structural configuration of geologic units need to be described in detail to define the major aquifer syustems in the area. The purpose of this report is to describe the subsurface geologic framework for Paleozoic, Mesozoic, and Cenozoic units in the southeast lowlands of Missouri and to correlate these units to those in adjecent States using geophysical and geologic methods (index map). Geophysical logs of wells were used to determine which units are aquifers or confining beds. The drilling of the U.S. Geological Survey test well 1-X in New Madrid County, Missouri, and the subsequent interpretation of geohydrologic data from the well have provided valuable information used in the preparation of this report.

Missouri↗

USGS2014

Fluctuations of ground‐water levels in Utah

Long‐time continuous records of the fluctuations of ground‐water levels have been obtained at relatively few locations in the United States. Among the few available records for Utah that extend continuously over a period of a year or more are those made in the Jordan River and Ogden valleys by the United States Geological Survey in cooperation with Salt Lake City and Ogden. A few of the records of water‐levels, with records of stream‐flow and precipitation, are shown in Figure 1. Most of these records were begun during 1931 or 1932. A State‐wide program of well‐observations was begun during the summer of 1935 and is now in progress, the work being done by the Geological Survey in cooperation with the Utah State Engineer.

Eos, Transactions, American Geophysical Union↗

USGS2019

Lithostratigraphic, geophysical, and hydrogeologic observations from a boring drilled to bedrock in glacial sediments near Nantucket Sound in East Falmouth, Massachusetts

In spring 2016, a 310-foot-deep boring (named MA–FSW 750) was drilled by the U.S. Geological Survey near Nantucket Sound in East Falmouth, Massachusetts, to investigate the hydrogeology of the southern coast of western Cape Cod. Few borings that are drilled to bedrock exist in the area, and the study area was selected to fill a gap between comprehensive geologic datasets inland to the north and marine geophysical data from beneath Nantucket Sound to the south. A permanent monitoring well (MA–FSW 750–0100) was installed in the boring upon the completion of the drilling and core collection. Observations from sediment cores and surface and borehole geophysical measurements were used to delineate three zones relevant to understanding groundwater flow at the study location. Shallow sands and gravels (0–107 feet [ft] below land surface [bls]) underlain by silt-rich fine and very fine sand (107–175 ft bls) form a zone of high permeability underlain by a zone of relatively lower permeability, referred to as the “shallow high-permeability” and “low-permeability” zones, respectively. A sharp lithological contact separating the shallow high-permeability and low-permeability zones may affect vertical flow of groundwater. Fine to coarse sand with intervals of clay and silt from 175 to 300 ft bls represent a deep zone of relatively high permeability, referred to as the “deep high-permeability” zone. A compacted, nonsorted unit (identified as basal till) and the bedrock surface were encountered at 300 and 305 ft bls, respectively. Hydraulic conductivity estimates from nuclear magnetic resonance logs and sediment grain-size distribution analyses indicated that the shallow high-permeability zone contributes substantially to the capacity of the aquifer to transmit groundwater at the study location. Results from geophysical surveys indicate a gradual transition from fresh to saline groundwater in the interval from 105 to 160 ft bls. Freshwater at the study site is present in the saturated unconsolidated sediments only in the 75 ft between 30 ft (the water table) and 105 ft bls in the shallow high-permeability zone. Sediments shallower than 175 ft bls closely resemble the downward fining post-Wisconsinan age deltaic and lacustrine deposits present in many parts of western Cape Cod; sediments deeper than 175 ft appear to be the product of earlier depositional processes more local to the southern coast of western Cape Cod. This study highlights how high-resolution observations of cored material coupled with a multitool geophysical approach can characterize a single boring to help better understand regional glacial history and hydrogeology.

Massachusetts↗