A hydrogeologic framework was developed by USGS during 2016-19 to describe the groundwater system on the Virginia Eastern Shore. This USGS data release contains text files of (1) interpreted borehole hydrogeologic-unit top-surface altitudes, (2) summary values of previously documented estimates of aquifer hydraulic properties, and (3) groundwater-sample chloride concentrations and well summary statistics. In addition are shapefiles of altitude contours for 10 hydrogeologic-unit top surfaces, and for the groundwater 250 milligrams per liter chloride-concentration surface. This data release supports the following publication: McFarland, E.R., and Beach, T.A., 2019, Hydrogeologic framework of the Virginia Eastern Shore: U.S. Geological Survey Scientific Investigations Report 2019-5093, 26 p., 13 pl., https://doi.org/10.3133/sir20195093.

This USGS data release contains (1) geologic-unit top-surface altitudes in boreholes and (2) aquifer-test time-series water-level drawdowns, recoveries, and supporting data from the Piney Point aquifer in Virginia from 2009 through 2015. Extents, compositions, configurations, and geologic relations of six geologic units that compose the Piney Point aquifer were determined from geologists’ logs of sediment core and cuttings, borehole geophysical logs, and drillers’ logs. The Piney Point aquifer is characterized to address information needs for water-resource management in the Virginia Coastal Plain. Information on the Piney Point aquifer can benefit water-resource management in siting production wells, predicting likely well yield, and anticipating water-level response to withdrawals.

This USGS data release contains (1) geologic-unit top-surface altitudes in boreholes and (2) aquifer-test time-series water-level drawdowns, recoveries, and supporting data from the Piney Point aquifer in Virginia from 2009 through 2015. Extents, compositions, configurations, and geologic relations of six geologic units that compose the Piney Point aquifer were determined from geologists’ logs of sediment core and cuttings, borehole geophysical logs, and drillers’ logs. The Piney Point aquifer is characterized to address information needs for water-resource management in the Virginia Coastal Plain. Information on the Piney Point aquifer can benefit water-resource management in siting production wells, predicting likely well yield, and anticipating water-level response to withdrawals.

Point data pp1773_unit_alt_boreholes represent the 309 locations of various types of boreholes that were used to determine the altitudes of each of the 16 hydrogeologic unit layers, plus the land surface altitude at the point location. The layers were used in the regional groundwater availability study of the aquifer system described in Professional Paper 1773, Groundwater Availability in the Atlantic Coastal Plain of North and South Carolina. Each layer is referred to as its model layer number as represented in the report PP1773. For clarity, they are listed below along with the aquifer unit or confining unit name in North Carolina and correlated name in South Carolina. L1 Surficial aquifer L2 Yorktown confining unit / Upper Floridan confining unit L3 Yorktown aquifer / Upper Floridan aquifer L4 Castle Hayne - Pungo River confining unit / Middle Floridan confining unit (To be referred to as "Castle Hayne / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne - Middle Floridan aquifer" in this document) L6 Beaufort confining unit / Gordon confining unit L7 Beaufort aquifer / Gordon aquifer L8 Peedee confining unit / Crouch Branch confining unit L9 Peedee aquifer / Crouch Branch aquifer L10 Black Creek confining unit / McQueen Branch confining unit L11 Black Creek aquifer / McQueen Branch aquifer L12 Upper Cape Fear confining unit / Charleston confining unit L13 Upper Cape Fear aquifer / Charleston aquifer L14 Lower Cape Fear confining unit / Gramling confining unit L15 Lower Cape Fear aquifer / Gramling aquifer L16 Lower Cretaceous confining unit and aquifer

Point data pp1773_unit_alt_boreholes represent the 309 locations of various types of boreholes that were used to determine the altitudes of each of the 16 hydrogeologic unit layers, plus the land surface altitude at the point location. The layers were used in the regional groundwater availability study of the aquifer system described in Professional Paper 1773, Groundwater Availability in the Atlantic Coastal Plain of North and South Carolina. Each layer is referred to as its model layer number as represented in the report PP1773. For clarity, they are listed below along with the aquifer unit or confining unit name in North Carolina and correlated name in South Carolina. L1 Surficial aquifer L2 Yorktown confining unit / Upper Floridan confining unit L3 Yorktown aquifer / Upper Floridan aquifer L4 Castle Hayne - Pungo River confining unit / Middle Floridan confining unit (To be referred to as "Castle Hayne / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne - Middle Floridan aquifer" in this document) L6 Beaufort confining unit / Gordon confining unit L7 Beaufort aquifer / Gordon aquifer L8 Peedee confining unit / Crouch Branch confining unit L9 Peedee aquifer / Crouch Branch aquifer L10 Black Creek confining unit / McQueen Branch confining unit L11 Black Creek aquifer / McQueen Branch aquifer L12 Upper Cape Fear confining unit / Charleston confining unit L13 Upper Cape Fear aquifer / Charleston aquifer L14 Lower Cape Fear confining unit / Gramling confining unit L15 Lower Cape Fear aquifer / Gramling aquifer L16 Lower Cretaceous confining unit and aquifer

This dataset describes water-level and associated data for wells open to various hydrogeologic units of Delaware that were used to create potentiometric surface contours for selected aquifers that underlie both the Coastal Plain of northern and central Delaware, and southern New Jersey. Water-level measurements were collected during October 2013.

This dataset describes water-level and associated data for wells open to various hydrogeologic units of Delaware that were used to create potentiometric surface contours for selected aquifers that underlie both the Coastal Plain of northern and central Delaware, and southern New Jersey. Water-level measurements were collected during October 2013.

A revision to the hydrogeologic framework of the Virginia coastal plain southwest of the James River was developed by USGS during 2019-2021. This revision includes modifications to existing understanding of the groundwater system in Prince George, Surry, Sussex, Isle of Wight, and Southampton counties and the cities of Franklin and Suffolk in southeast Virginia. This USGS data release contains a csv file of interpreted borehole hydrogeologic-unit top-surface altitudes, a shapefile of the study area extent, a shapefile of faults within the study area, shapefiles of altitude contours for 12 hydrogeologic-unit top surfaces, shapefiles of hydrogeologic-unit margins for 10 hydrogeologic-units in the coastal plain of Virginia southwest of the James River. This data supports the following publication Caldwell, S. H., and McFarland, E. R., 2022 , Revision to the Virginia Coastal Plain Hydrogeologic Framework Southwest of the James River: U.S. Geological Survey Scientific Investigations Report 2022-XXXX, 33 p., DOILINK

A revision to the hydrogeologic framework of the Virginia coastal plain southwest of the James River was developed by USGS during 2019-2021. This revision includes modifications to existing understanding of the groundwater system in Prince George, Surry, Sussex, Isle of Wight, and Southampton counties and the cities of Franklin and Suffolk in southeast Virginia. This USGS data release contains a csv file of interpreted borehole hydrogeologic-unit top-surface altitudes, a shapefile of the study area extent, a shapefile of faults within the study area, shapefiles of altitude contours for 12 hydrogeologic-unit top surfaces, shapefiles of hydrogeologic-unit margins for 10 hydrogeologic-units in the coastal plain of Virginia southwest of the James River. This data supports the following publication Caldwell, S. H., and McFarland, E. R., 2022 , Revision to the Virginia Coastal Plain Hydrogeologic Framework Southwest of the James River: U.S. Geological Survey Scientific Investigations Report 2022-XXXX, 33 p., DOILINK

From April 2013 to August 2015, the U.S. Geological Survey, in cooperation with the Town of Enfield and the Tompkins County Planning Department, collected horizontal-to-vertical seismic soundings at 69 locations in the Enfield Creek valley to help determine thickness of the unconsolidated deposits and depth to bedrock. The HVSR technique, commonly referred to as the passive-seismic method, is used to estimate the thickness of unconsolidated sediments and the depth to bedrock (Lane and others, 2008). The passive-seismic method uses a single, broad-band three-component (two horizontal and one vertical) seismometer to record ambient seismic noise. In areas that have a strong acoustic contrast between the bedrock and overlying sediments, the seismic noise induces resonance at frequencies that range from about 0.3 to 40 Hz. The ratio of the average horizontal-to-vertical spectrums produces a spectral-ratio curve with peaks at fundamental and higher-order resonance frequencies. The spectral ratio curve (the ratio of the averaged horizontal-to-vertical component spectrums) is used to determine the fundamental resonance frequency that can be used along with an average shear-wave velocity or a power-law regression equation to estimate sediment thickness and depth to bedrock (Lane and others, 2008; Brown and others, 2013; Fairchild and others, 2013; Chandler and others, 2014; and Johnson and Lane, 2016). The HVSR data presented in this data release were collected at each site for 30 minutes using a Tromino Model TEP-3C three-component seismometer. The data were processed with Grilla 2012 version. 6.2 software to 1) remove anthropogenic noise, 2) convert the time-domain data to frequency domain, 3) compute and plot the spectral ratio curve, and 4) determine the resonance frequency. This data release presents the resonance frequency peaks identified from the HVSR measurements. Also presented are reported depth-to-bedrock data for wells located at or near HVSR data-collection sites in the Town of Enfield for use in comparison of HVSR forward model depths to reported well depths. Raw and processed HVSR data for each HVSR measurement are presented in the attached. The HVSR data-collection sites are designated by a county sequential numbering system (TMHVSR79, TMHVSR80, etc. where TM indicates Tompkins County). References Brown, C.J., Voytek, E.B., Lane, J.W., Jr., and Stone, J.R., 2013, Mapping bedrock surface contours using the horizontal-to-vertical spectral ratio (HVSR) method near the middle quarter area, Woodbury, Connecticut: U.S. Geological Survey Open-File Report 2013–1028, 4 p., available at http://pubs.usgs.gov/of/2013/1028. Chandler, V. W., and Lively, R. S., 2014, Evaluation of the horizontal-to-vertical spectral ratio (HVSR) passive seismic method for estimating the thickness of Quaternary deposits in Minnesota and adjacent parts of Wisconsin: Minnesota Geological Survey Open File Report 14-01, 52 p. Fairchild, G.M., Lane, J.W., Jr., Voytek, E.B., and LeBlanc, D.R., 2013, Bedrock topography of western Cape Cod, Massachusetts, based on bedrock altitudes from geologic borings and analysis of ambient seismic noise by the horizontal-to-vertical spectral-ratio method: U.S. Geological Survey Scientific Investigations Map 3233, 1 sheet, maps variously scaled, 17-p. pamphlet, on one CD–ROM. (Also available at http://pubs.usgs.gov/sim/3233.) Johnson, C. D. and Lane, J. W., 2016, Statistical comparison of methods for estimating sediment thickness from horizontal-to-vertical spectral ratio (HVSR) seismic methods: An example from Tylerville, Connecticut, USA, in Symposium on the Application of Geophysics to Engineering and Environmental Problems Proceedings: Denver, Colorado, Environmental and Engineering Geophysical Society, pp. 317-323. https://doi.org/10.4133/SAGEEP.29-057. Lane, J.W., Jr., White, E.A., Steele, G.V., and Cannia, J.C., 2008, Estimation of bedrock depth using the horizontal-to-vertical (H/V) ambient-noise seismic method,