RECOMMENDATIONS 



1. Provide a realistic model of the sea floor for ex- 

 perimental and theoretical studies, whenever underwater 

 sound experiments involve bottom-bounce propagation. 



2. In future geoacoustic models, include detailed 

 data on the sub-bottom layering for the first few tens of 

 feet. 



3. Devote theoretical and experimental study to 

 (a) mass physical properties of the sediments -- such as 

 the velocity of the elastic shear wave and attenuation of the 

 compressional wave at the frequencies most used in sonar 

 technology -- and (b) the vertical gradient of sound velocity 

 in the upper sediments. 



4. Facilitate the prediction of geoacoustic properties 

 by investigating sedimentary processes and areal distribu- 

 tions of sediments. 



ADMINISTRATIVE INFORMATION 



Work was performed under SR 004 03 01, Task 0539 

 (NEL L40151), as assigned by BuShips ltr ser 341-065 of 

 30 Sept 6 0, by members of the Marine Environment Division. 

 The report covers various field work and laboratory studies 

 since 196 0; especially, work done in the Bering Sea in 196 0, 

 and on sediments from the Experimental Mohole (Guadalupe 

 Site). The report was approved for publication 19 April 1965. 

 It is the first of a projected series of geoacoustic models 

 of many areas. 



Suggestions and criticism from G. H. Curl, K. V. 

 Mackenzie, E. C. LaFond, D. G. Moore, and E. C. 

 Buffington are appreciated. 



Biological samples were taken and preserved by 

 John Tibbs of the University of Southern California, working 

 under ONR Contract 228/19/NR 107-567; arrangements for 

 his participation in the project were made by B. K. Couper 

 of BUSHIPS and Dr. S. R. Galler of ONR. 



