96 THE NAVY OCEAN SCIENCE PROGRAM 



Studies of sediment in future programs should be directed 

 toward mechanical properties, both those influencing acoustics 

 £ind those determining the bearing strength and stability of the 

 sediment, as well as the familiar mineralogical and paleonto- 

 logical pursuits. The process of compaction, imperfectly described, 

 can be studied and understood best in deep-sea sediments. 

 These studies should be paralleled by consideration of bottom 

 currents and sediment transport. Chemical and biological pro- 

 cesses that influence the gradual formation of sedimentary rock 

 bear on the same questions as mechanical compaction and should 

 be studied as part of this broad program. Some of the special 

 topics concerned with sediments are sketched below, not as an 

 exhaustive discussion but as an indication of emphasis. 



The study of gross structure and properties of all oceanic 

 sediments seriously began with the wide use of seismic-reflection 

 profilers. These instruments have far more potential than has 

 been realized in any current sustained program. The develop- 

 ment of this line of investigation will be encoLiraged because of its 

 high relevance to Navy sonsir problems and because it is a power- 

 ful tool for the study of the oceans. Useful hypotheses of the past 

 five years which depend on the measurement of sedimentary 

 structures deep below the ocean floor have concerned not only the 

 structures themselves but also the deep circulation of the ocean. 

 These hypotheses come from mere description of the structures. 

 The resolution of the method is being improved, and the depth of 

 penetration increased. It has been possible to make promising 

 correlations between the energetics of the reflections and the 

 geologic characteristics of the sediments. This last line of in- 

 quiry, of obvious importance to sonar, will be encouraged. 



In enclosed basins and other areas where fine, porous clays 

 dominate in the sediment, the sound velocity of the bulk is less 

 than that of the interstitial water because of the mass loading of 

 the sediment. In the subsequent development of the deposit the 

 clays are compacted by the overlying sediments. Thus the sound 

 velocity increases with depth. This process, long known, has 

 received little attention in the deep sea until very recently. Its 

 acoustic effects are neither widely nor completely understood. 



