650-m Profiles of Self-Potential, Contact Resistance, and Electric Resistance Tomography Measurements Adjacent to Hamilton Creek, Burnet County, Texas, July 2017 - January 2018

This data release consists of three different types of geoelectric data measured along three curvilinear profiles during two separate geophysical surveys completed on July 9, 2017 and January 9, 2018. The datasets include three self-potential (SP) profiles, two spatially-coincident electric contact-resistance (CR) profiles, and two spatially-coincident electric resistance tomography (ERT) tomograms. All profiles were oriented in a northeast-southwest alignment along 650 meters of a natural berm parallel to a surface-water reservoir to the west and Hamilton Creek to the east, in Burnet County, Texas. The profiles along the berm began at latitude and longitude coordinates (30.716319o N, -98.229917o W) and terminated at latitude and longitude coordinates (30.712362o N, -98.232302o W) at the southern end. The resulting datasets contain (1) 265 SP measurements acquired along three separate profiles using a high resolution (1 Microvolt) Agilent U1252 data-logging multi-meter (Agilent Technologies, Santa Clara, Calif.) and two non-polarizing Cu-CuSO4 electrodes; (2) 162 CR measurements along profiles that were spatially-coincident with two of the SP profiles; and (3) 11,328 electric resistance measurements acquired with an IRIS Syscal Pro Switch 96 instrument (Iris Instruments, Orleans, France) along profiles that were spatially-coincident with two of the SP profiles. Additionally, the datasets include global positioning system (GPS) coordinates of the SP, CR, and ERT measurement locations, which were measured with a hand-held Garmin GPSMAP 62s receiver (Garmin Ltd., Canton of Schaffhausen, Switzerland) with two-meter accuracy. The data were collectively interpreted to (1) identify areas beneath the profiles where preferential groundwater seepage was occurring at the time the surveys were completed, and (2) image dissolution cavities that may be present within the subsurface geoelectric structure of the Tanyard and Gorman Formations of the Ellenburger-San Saba aquifer and the San Saba Member of the Wilberns Formation to depths of 100 meters (m). Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.