An essential book for all students and scientists in the field, Part A of Geophysical Field Theory and Method describes the physical and mathematical principles of geophysical methods, specifically the behavior of gravitational, electrical, and magnetic fields. The broader use of these methods underlines the far-reaching appeal of this book. Oil and mineral prospecting, solving groundwater and engineering problems, and well-logging are just some of the activities which involve geophysical methods. Parts B and C will be devoted to the theory of fields and applied to electromagnetic, seismic, nuclear, and geothermal methods. Presents physical principles of geophysical methodsCovers physical laws which govern field behavior and their areas of applicationExamines the influence of a medium on a field, and the distribution of field generatorsPresents formulation of conditions when physical laws cannot be used directly for field calculationsExamines systems of field equations and their neccesity when some of the field generators are unknownExplains the formulation of boundary value problems and their importance in determining the fieldFeatures auxiliary fields and their role in field theoryPresents approximate methods of field calculation