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Too often geophysical surveys of the near surface are a last resort. Direct sampling by trenching or trial pits is relatively cheap and gives a geologist or engineer a direct view of the target. Boreholes are a natural extension from trial pits since, although they sample in depth at only one point, they may recover physical samples of the material from the units under investigation. Geophysics is frequently regarded as useful in terms of being noninvasive, but lacking in resolution, and incapable of coping with complex near-surface materials. This presents a strange contradiction, since geophysical surveys are accepted as a good tool for archaeological surveys, where the main purpose is to identify inhomogeneity in the near surface with high resolution. Archaeogeophysical surveys are highly detailed, but slow and expensive. Running surveys of the same area with multiple geophysical methods is even more expensive, though this offers the prospect of improved characterization of subsurface materials.
Hill et al. (Thu,) studied this question.