The geomagnetic field observed on the surface of the earth has been an important source of information on the dynamic behavior of the magnetosphere. Because the. magnetosphere and its environment are filled with plasma in which electric current can easily flow, dynamic processes that occur in the magnetosphere tend to produce perturba tions in the geomagnetic field. Geomagnetic data have therefore pro vided valuable means for sensing the processes taking place at remote locations, and such basic concepts as the magnetosphere, solar wind, and trapped radiation were derived in early, presatellite days from geomagnetic analyses. Because of this advantage, geomagnetic observations have been widely utilized for monitoring the overall condition of the magneto sphere. Although the advent of space vehides has made it possible to observe magnetospheric processes in situ, supplementary information on the overall magnetospheric condition is frequently found to be indispensable for interpreting these observations in the proper perspec tive. Hence for magnetospheric physicists involved in various branches of the field it has become a common practice to employ geomagnetic data as a basic diagnostic tool."

Studies related to the earth and planets along with their surroundings are of great concern for modern scientists. Global geodynamics as represented by plate tectonics has now become one of the most powerful tools by which we can study the causes of earthquakes, volcanic eruptions, mountain formation and the like. Various missions sent out to space, manned or of the moon, Mars, Venus and unmanned, brought out geoscientific features other planets. Earthquake prediction that was the business of astrologers and fortune-tellers some twenty years ago, has now grown up to be an important science. A number of destructive earthquakes were successfully forecast in the People's Republic of China. In the light of the above-mentioned and other accomplishments in geosciences, we feel that it is a good thing to publish a series of monographs which review selected topics of earth and planetary sciences. We are of course well aware of the fact that similar monographs have been and will be published from overseas publishers. The series, which we plan to publish, will therefore stress Japanese work. But we hope that the series will also include review articles by distinguished overseas authors.

Studies related to the earth and planets along with their surroundings are of great concern for modern scientists. Global geodynamics as represented by plate tectonics has now become one of the most powerful tools by which we can study the causes of earthquakes, volcanic eruptions, mountain formation and the like. Various missions sent out to space, manned or of the moon, Mars, Venus and unmanned, brought out geoscientific features other planets. Earthquake prediction that was the business of astrologers and fortune-tellers some twenty years ago, has now grown up to be an important science. A number of destructive earthquakes were successfully forecast in the People's Republic of China. In the light of the above-mentioned and other accomplishments in geosciences, we feel that it is a good thing to publish a series of monographs which review selected topics of earth and planetary sciences. We are of course well aware of the fact that similar monographs have been and will be published from overseas publishers. The series, which we plan to publish, will therefore stress Japanese work. But we hope that the series will also include review articles by distinguished overseas authors.