Radiometric (gamma spectrometry) measurements were made during walking surveys in the eastern Adirondack Highlands, New York using a GF Instruments Gamma Surveyor. The surveys involved recording measurement averages over 30-second intervals while holding the instrument approximately 1 meter above the ground. Locations were obtained via a handheld GPS. The surveys were conducted near magnetite-apatite deposits and in areas with mine tailings. For more information on radiometric methods, please see the International Atomic Energy Agency publication "Guidelines for Radioelement Mapping Using Gamma Ray Spectrometry Data" (2003).

This line shapefile documents ground surface exposure rate from total terrestrial gamma activity, and calculated from aerial gross count data (all gamma events in the range of 38-3026 keV). Forty one (41) aerial radiological surveys of potential uranium mining areas (1,144 square miles) were conducted within the Navajo Nation during the period from October 1994 through October 1999. The US Environmental Protection Agency (USEPA) Region 9 funded the surveys and the US Department of Energy (USDOE) Remote Sensing Laboratory (RSL) in Las Vegas, Nevada conducted the aerial surveys. The aerial survey data were used to characterize the overall radioactivity (ground surface exposure rate) and excess Bismuth 214 levels within the surveyed areas.