Speiss, Mudie and Lowenstein 



occurred iii some portions of the Hawaiian location and in that region there 

 were areas showing very thin sediment cover which correlated with very 

 patchy sonar returns as shovra in Fig. 11. This record is of double useful- 

 ness inasmuch as it shows the sort of roughness which the non-sediment 

 covered portions of the sea floor can have while at the same time giving 

 indication of the resolution of which the equipment is capable. This provides 

 reassurance that the much more extensive smooth areas are in fact (for ob- 

 jects of this size) essentially featureless. In this picture the nearly round 

 shadow at about 1157 implies an object 14 feet high and 90 feet wide along the 

 track at a distance of about 400 feet to one side of the track. 



A knowledge of general geological sea floor patterns makes it 

 clear that one can predict that search for objects having characteristic di- 

 mensions of 10 feet or more should be highly effective in about 80% of the 

 northeast Pacific. In volcanically controlled areas, as off Hawaii, the per- 

 centage will perhaps drop lower, with areas showing no sediment cover pro- 

 viding particularly difficult situations. It thus appears that any search for 

 large objects in the deep northeast Pacific can be conducted using simple 

 towed instruments in conjunction with small submarines with an appropriate 

 division of effort between the two. Areas of steep terrain or those with 

 scant sediment cover could be assigned initially for detailed search using 

 manned craft with the towed gadgetry covering the usually much larger 

 sediment-covered area and locating within it any possible targets or small 

 patches of rough terrain for later manned investigation. At the present 

 time, with only bathyscaphes available for detailed observations, this might 

 still throw too much load on the manned portion of the system. However, as 

 craft having greater mobility become available the combined system should 

 approach compatibility with the environmental situation. 



It should be emphasized that only a small fraction of the sea floor 

 has been sampled in this manner thus far, although areas were chosen to 

 allow the most significant inferences to be drawn. Further observations in 

 areas of different geological types are still required to allow formation of a 

 truly worldwide picture. 



We would like to acknowledge the participation of the engineering 

 staff which designed and built the equipment which made these observations 

 possible: Messrs. M. S. McGehee, C. S. Mundy, D. E. Boegeman and M. 

 Benson. It is also a pleasure to express our thanks to Capt. T. Hansen and 

 the crew of the THOMAS WASHINGTON (AGOR-lO) for their very effective 

 support of our seagoing work, which was supported by ONR and DSSP. 



73 



