ABSTRACT
Geophysical investigation is as old as Man. Evidence from prehistory points to an extensive knowledge of stone, use of oil seeps, metallic ore, and many other uses of early geophysics and geology. Prehistoric mines still exist in Europe, and those in North America date to before Europeans arrived to this continent. The Chinese introduced drilling and the use of drilling muds in about 256 B.C. for the production of brine. Their methods changed little in the next 1900 years. It is highly probable that similar drilling methods were used in other places in the world, through history. Early gamma ray measurements were adopted directly from the petroleum industry. The mineral industry, however, had a long history of quantitative use of several of the methods which were used qualitatively in petroleum work. The gamma ray spectrograph had been used quantitatively in airborne and surface measurements for some time.
