A majority of the membership of the Society of Exploration Geophysicists is engaged, directly or indirectly, in the exploration for oil and gas. Since the habitat of these deposits is confined almost conclusively to the sedimentary portion of the earth's crust, it is only natural that this portion constitutes their primary field of interest. Their concern with volcanic terrain is often but a negative one, being directed towards the determination of their occurrences and outlines for the purpose of eliminating them as potential oil hunting grounds. This, at least, has been the experience of the writer during a lifetime of oil exploration work. It will, therefore, be of interest to this group of geophysicists to take cognizance of another field of application of the geophysical methods: their use in the investigation of volcanic and impact structures. While this activity is presently of limited extent and confined to the earth, it may in the foreseeable future be extended to the exploration of the moon. The writer had the good fortune to become more fully aware of this field of activity as the representative of the SEG at the recent Lunar Geological Field Conference.