The art of exploration geophysics is reviewed with reference to classical and current literature. Its main features are described, the state of instrumentation and theory in it is discussed, and the problems it has yet to solve are examined.
Exploration geophysics is both a science and an industry. As a science it draws on its parent sciences of physics and geology, and it has a reciprocal relationship with its sister disciplines of seismology and geodesy. Since its predictions often cannot be verified, it lacks one indispensable ingredient of science—the power of self criticism. It also suffers because its discoveries are proprietary and therefore often not published to be built on or challenged. In spite of these handicaps, its scientific status is rising. More trained workers than ever before are in the field, and their publications are of better quality.
As an industry, exploration geophysics has long had the financial support that public funding has only recently given to science in general. It has served the demand for mineral discoveries well, but has sometimes failed to give the best possible support to its clients through lack of rapport between those who study problems and those who make decisions about them.
The instruments and devices used by exploration geophysics have in general surpassed its fundamental needs. In 1930 the reflection seismograph was untested, and the field gravity meter was not invented, although they were clearly needed, and their prototypes, the refraction seismograph and the torsion balance, were plainly inadequate. Now it is possible to take almost any geophysical measurements found desirable, and the instrumental problem is usually to take them faster and with lighter and more dependable gear.
The present frontiers of the art are not in the observing of data but in their interpretation and application to the search for minerals. The interpretation of seismic records is still in a relatively primitive form. How far it will be developed in the future depends on how acutely it is needed, but it is not easy to see the end of the data-processing techniques that are now being studied. The interpretation of gravimetric, magnetic, electrical, and radioactivity observations still requires personal skill, although automatic computing techniques have been applied to the first two types.