Geodynamics: progress, problems, and prospects

The development of geotectonic theory has been relatively rapid in recent years, culminating with the plate tectonics theory. Although many of the basic data and ideas which support this theory have been gathered patiently over the preceding half-century, recent advances in our knowledge of the structure and geophysics of ocean basins clearly have contributed to the accelerated evolution of geotectonic thought. The plate tectonics theory has elegantly simple basic principles, and is currently the most satisfactory and widely accepted tectonic theory. It postulates that the major zones of deformation of the Earth's crust are located at the margins of large plates of the lithosphere, which are in motion relative to each other. The geometry of motion is fairly simple, and allows geophysical predictions which can be tested. Although a great variety of geological and geophysical observations can be related through this theory, many enigma in geodynamics remain. Accepting, therefore, the plate tectonics theory in principle, the writer isolates some enigmatic geological and geophysical problems which require further study. Some such areas in South America are especially mentioned. which are of great interest to geodynamics in general.