This is a general review of new developments in geophysical exploration in 1957. In the Eastern Hemisphere, the strong emphasis on the use of refined seismograph techniques in virgin territories despite extreme operating problems is a development of primary importance. In mining geophysics a new Swedish development employs a rotary electromagnetic field and two-plane operation to improve substantially the economy and effectiveness of reconnaissance for conductive ore-bodies.
In the United States new developments include work on a method of seismic exploration using continuous waves rather than pulses, the incorporation of transistors into seismic units, a trend toward simplified equipment for plotting seismic record sections, an electrical prospecting method which permits detection of near surface structures in water-covered areas, and the increased use of continuous velocity logs. Other developments have occurred in the field of chemical logging, including the use of mass spectrometers, infrared analyzers, and gas chromatographic columns. Academic research into techniques for dating feldspar-bearing rocks has advanced spectacularly. It is now possible to obtain dates on certain kinds of rocks extending from a few thousand years to a few billion years in age.