Radiometric (gamma spectrometry) measurements were made during walking surveys in northern Maine using a GF Instruments Gamma Surveyor. These 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. Data were collected over and in the vicinity of a radiometric thorium anomaly identified via an airborne survey. For more information on radiometric methods, please see the International Atomic Energy Agency publication "Guidelines for Radioelement Mapping Using Gamma Ray Spectrometry Data" (2003). Reference: International Atomic Energy Agency, 2003, Guidelines for Radioelement Mapping Using Gamma Ray Spectrometry Data, IAEA-TECDOC-1363, IAEA, Vienna, 173 pp.