In July 1972, the U.S. Office of Naval Research identified several areas that it interpreted as being of interest to the U.S. Navy. Four of these research areas were then selected for their special importance in understanding physical processes on the ocean floor. In some of these, a great wealth of data has accumulated over the past two or three decades, but controversy exists in the interpretation of the results. In others, new techniques have re cently been devised that could lead to the collection and synthesis of new information. There was yet a third area in which little study had been undertaken and the results available appeared of great potential importance. The latter subject constitutes the title of this volume. To assess the information available and to facilitate plans for further research in the fields of interest that had been identified, the U.S. Office of Naval Research sponsored four symposia. The first was held in November 1972 at the University of California Con ference Center, Lake Arrowhead. The title of the symposium was "Natural Gases in Marine Sediments and Their Mode of Distribution." Twenty lectures were presented over a three-day period. All but two participants at this symposium subsequently submitted papers, which are published in this volume. In addition, Dr. K.O. Emery, who did not attend the symposium, supplied a manuscript on a topic most re levant to the subject matter discussed."