PROBLEM 



Determine and study those characteristics of the sea 

 floor that affect the propagation of acoustic energy in the 

 sea. Specifically, investigate the character, magnitude, 

 and distribution of sea floor microrelief and its superposi- 

 tion on intermediate and major underwater topographic 

 features. 



RESULTS 



1. More than 700 NEL sea floor photographs, obtained 

 over the past ten years, in a wide variety of environments, 

 have been analyzed. The bottom microrelief has been 

 related to the major agencies responsible for its formation 

 and, on this basis, five predominating types of microrelief 

 have been defined. 



2. General ranges in the vertical height and horizontal 

 extent of the microrelief have been determined for the upper 

 exposed surfaces of 39 intermediate underwater features 

 that are, in turn, related to 12 major features or provinces. 



3. Microroughness ratings, on a numerical scale of 



1 through 5, are predicted for normal bottom environments. 

 These ratings should prove useful in acoustic problems. 



4. Isoroughness zones have been mapped for large 

 portions of the Pacific and adjacent ocean areas. 



