In support of a groundwater-flow model of the Virginia Eastern Shore, altitudes were determined for the tops of hydrogeologic surfaces, including incised paleochannel surfaces, that compose the framework within the model area. Rasters were generated from the altitude data for the tops of the surficial aquifer, upper confining unit, upper aquifer, middle confining unit, middle aquifer, lower confining unit, lower aquifer, Saint Marys confining unit, paleochannel upper aquifer, paleochannel confining unit, and paleochannel lower aquifer (McFarland and Beach, 2019; McFarland, 2019). This data release includes the 11 rasters mentioned above for the Virginia Eastern Shore, in tiff format. Altitude contours from existing shapefiles in McFarland (2019) and Andreasen and others (2013) were the primary sources for unit top altitudes represented by the rasters. In the northern part of the study area, the surface altitude contours from Andreasen and others (2013) were used to supplement the contours from McFarland (2019). Topobathymetric data (Faunce and Rapp, 2020) were the source for development of the raster representing the top of the surficial aquifer.

In support of a groundwater-flow model of the Virginia Eastern Shore, altitudes were determined for the tops of hydrogeologic surfaces, including incised paleochannel surfaces, that compose the framework within the model area. Rasters were generated from the altitude data for the tops of the surficial aquifer, upper confining unit, upper aquifer, middle confining unit, middle aquifer, lower confining unit, lower aquifer, Saint Marys confining unit, paleochannel upper aquifer, paleochannel confining unit, and paleochannel lower aquifer (McFarland and Beach, 2019; McFarland, 2019). This data release includes the 11 rasters mentioned above for the Virginia Eastern Shore, in tiff format. Altitude contours from existing shapefiles in McFarland (2019) and Andreasen and others (2013) were the primary sources for unit top altitudes represented by the rasters. In the northern part of the study area, the surface altitude contours from Andreasen and others (2013) were used to supplement the contours from McFarland (2019). Topobathymetric data (Faunce and Rapp, 2020) were the source for development of the raster representing the top of the surficial aquifer.

This polyline shapefile consists of digital contours that represent the potentiometric-surface altitude of water in the Lloyd and contiguous North Shore aquifer beneath Long Island, New York. The U.S. Geological Survey constructed a potentiometric-surface altitude map using ground-water levels measured in the Lloyd and North Shore aquifers during the spring of 2013. Contours were constructed at a scale of 1:125,000 from water-level data collected at 66 groundwater monitoring wells. The potentiometric-surface altitude contours were digitized and compared to 1997, 2006, and 2010 potentiometric-surface altitude maps. The contours range from -10 to 60 feet at 5 foot intervals above and below the National Geodetic Vertical Datum of 1929. This polyline shapefile is a digital representation of the potentiometric-surface contours presented in sheet 3 of Scientific Investigations Map 3326.

This polyline shapefile consists of digital contours that represent the potentiometric-surface altitude of water in the Lloyd and contiguous North Shore aquifer beneath Long Island, New York. The U.S. Geological Survey constructed a potentiometric-surface altitude map using ground-water levels measured in the Lloyd and North Shore aquifers during the spring of 2013. Contours were constructed at a scale of 1:125,000 from water-level data collected at 66 groundwater monitoring wells. The potentiometric-surface altitude contours were digitized and compared to 1997, 2006, and 2010 potentiometric-surface altitude maps. The contours range from -10 to 60 feet at 5 foot intervals above and below the National Geodetic Vertical Datum of 1929. This polyline shapefile is a digital representation of the potentiometric-surface contours presented in sheet 3 of Scientific Investigations Map 3326.

This polyline shapefile consists of digital contours that represent the potentiometric-surface altitude of water in the Lloyd and contiguous North Shore aquifer beneath Nassau and Suffolk Counties, Long Island, New York. The U.S. Geological Survey constructed a potentiometric-surface altitude map using ground-water levels measured in the Lloyd and North Shore aquifers during the spring of 2016. Contours were constructed at a scale of 1:125,000 from water-level data collected at 60 groundwater monitoring wells. The potentiometric-surface altitude contours were digitized and compared to 1997, 2006, 2010 and 2013 potentiometric-surface altitude maps. The contours range from -5 to 60 feet at 5 foot intervals above and below the National Geodetic Vertical Datum of 1929. This polyline shapefile is a digital representation of the potentiometric-surface contours presented in sheet 3 of Scientific Investigations Map 3398.

This polyline shapefile consists of digital contours that represent the potentiometric-surface altitude of water in the Lloyd and contiguous North Shore aquifer beneath Nassau and Suffolk Counties, Long Island, New York. The U.S. Geological Survey constructed a potentiometric-surface altitude map using ground-water levels measured in the Lloyd and North Shore aquifers during the spring of 2016. Contours were constructed at a scale of 1:125,000 from water-level data collected at 60 groundwater monitoring wells. The potentiometric-surface altitude contours were digitized and compared to 1997, 2006, 2010 and 2013 potentiometric-surface altitude maps. The contours range from -5 to 60 feet at 5 foot intervals above and below the National Geodetic Vertical Datum of 1929. This polyline shapefile is a digital representation of the potentiometric-surface contours presented in sheet 3 of Scientific Investigations Map 3398.

PP1773_unit_alt_grid is a polygon shapefile of surface altitudes for 16 hydrogeologic units as described in report Professional Paper 1773. Surface altitudes were interpolated and discretized to the 2-mile by 2-mile rotated grid used to simulate groundwater flow in the Atlantic Coastal Plain of North and South Carolina. Altitudes are available for 17 surfaces, hydrogeologic unit layer 1 (top - land surface) through Layer 16 (top and bottom). Each hydrogeologic unit 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 its 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 confining unit / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne aquifer / 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

PP1773_unit_alt_grid is a polygon shapefile of surface altitudes for 16 hydrogeologic units as described in report Professional Paper 1773. Surface altitudes were interpolated and discretized to the 2-mile by 2-mile rotated grid used to simulate groundwater flow in the Atlantic Coastal Plain of North and South Carolina. Altitudes are available for 17 surfaces, hydrogeologic unit layer 1 (top - land surface) through Layer 16 (top and bottom). Each hydrogeologic unit 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 its 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 confining unit / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne aquifer / 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

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.

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.