The seismic method in geophysics has been very thoroughly applied to prospecting for oil, but the techniques developed are not well suited to shallow surveying. A typical shallow survey is described to illustrate some of the shortcomings of the standard seismic techniques in this sphere. A full critique reveals both practical and fundamental limitations, the origin of most of which may be traced to the explosive source. Published data on the form of the explosive impulse suggest that it is inherently unsuitable for shallow surveying. The electromechanical source promises to overcome this difficulty by providing an impulse having any desired frequency and duration.