1. A general term applied to the investigation activities at a specific location that examine natural phenomena and human-induced conditions important to the resolution of environmental, safety, and water-resource issues. 2. The program of exploration and research, both in the laboratory and in the field, undertaken to establish the geologic conditions and the ranges of the geologic parameters of a particular site relevant to the program. It includes borings, surface excavations, excavation of exploratory shafts, limited subsurface lateral excavations and borings, and in situ testing at depths needed to determine the suitability of the site for a geologic repository, but does not include preliminary borings and geophysical testing needed to decide whether site characterization should be undertaken.