1.1 ,This guide covers the selection of surface geophysical methods, as commonly applied to geologic, geotechnical, hydrologic, and environmental site investigations and subsequent site characterization, as well as forensic and archaeological applications. These geophysical methods are rarely the sole method used in the site investigation and are often used for pre-screening to guide how and where drilling, sampling or other targeted in-situ testing are conducted. This guide does not describe the specific procedures for conducting geophysical surveys. Individual guides have been developed for many surface geophysical methods.