Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:°F = (1.8 × °C) + 32 Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27). Altitude, as used in this report, refers to distance above or below the vertical datum. Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25 °C). Concentrations of chemical constituents in water are given in milligrams per liter (mg/L) or micrograms per liter (µg/L).

Cover.Outcrop of Potomac aquifer sediments at Drewry's Bluff on the James River, approximately 7 miles downstream from Richmond, Virginia. Typical sediment lithologies are locally diverse and complexly distributed. At top, coarse-grained quartzo-feldspathic sands are cross bedded and iron stained. Near center, a black 2-foot wide angular rip-up boulder of organic-rich clay is flanked by quartzite gravel. Underlying tan medium-grained quartz sand is weakly bedded. At bottom, beds of black organic-rich clay and white kaolinized feldspar sand are broken and truncated by quartzite gravel.The outcrop is one of a series of sparse exposures of Potomac aquifer sediments, limited and localized along most of the Fall Zone in Virginia to incised major rivers. The bluff forms a 90-foot escarpment along the cut bank of the James River on the outside of a meander bend.For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit

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For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod/.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation:McFarland, E.R., 2017, Hydrogeologic framework and hydrologic conditions of the Piney Point aquifer in Virginia: U.S. Geological Survey Scientific Investigations Report 2017-5041, 63 p., 2 pl., and CD-ROM, https://doi.org/10.3133/ sir20175041. AcknowledgmentsThis study was supported by the Virginia Department of Environmental Quality (VA DEQ). Special thanks for program planning go to Scott W. Kudlas and T. Scott Bruce of the VA DEQ. C. Richard Berquist of the Virginia Division of Geology and Mineral Resources generously provided geologic logs of boreholes in the southwestern part of the study area, and John T. Haynes of James Madison University generously provided petrographic analyses of limestone of the Piney Point Formation. Thanks also are extended to the many drillers and owners of water-supply wells, who provided well data from across the Virginia Coastal Plain. The scientific integrity of this report was aided greatly by reviews from Mark D. Kozar and Jason P. Pope of the U.S. Geological Survey (USGS). The editorial and graphical quality of the report was aided greatly by Ruth Larkins and Denis Sun of the USGS.This project has been funded in part by the U.S. Environmental Protection Agency (EPA) under assistance agreement BG-98392505-1 to the VA DEQ. The contents of this document do not necessarily reflect the views and policies of the EPA, nor does the EPA endorse trade names or recommend the use of commercial products mentioned in this document. DatumVertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).Altitude, as used in this report, refers to distance above the vertical datum. Supplemental InformationConcentrations of chemical constituents in water are given in milligrams per liter (mg/L). Hydrogeologic Framework and Hydrologic Conditions of the Piney Point Aquifer in VirginiaBy E. Randolph McFarland AbstractThe Piney Point aquifer in Virginia is newly described and delineated as being composed of six geologic units, in a study conducted by the U.S. Geological Survey in cooperation with the Virginia Department of Environmental Quality (VA DEQ). The eastward-dipping geologic units include, in stratigraphically ascending order, the