8. Density of the surficial bottom sediments. 



"D" followed by three digits with decimal understood 

 between 1st and 2nd digit. Note: density will be es- 

 timated. 



9. Attenuation in the surficial sediments. 



"Y" followed by three digits with the decimal under- 

 stood between the 2nd and 3rd digit (units are in dB/ft) 

 followed by "K" and three digits with the decimal 

 understood between the second and third digits (units 

 are kilocycles). 



Sample message: 



"A85T340S4V510P102D16 0Y153K183" 



Means: "At a point 85 miles from the southern end of line 

 S 1 , the thickness of sediment over a prominent reflector is 

 340 feet; the sediment type is silt; the velocity of sound in 

 the sediment (from the in situ velocity meter) is 5100 ft/ 

 sec; the ratio of velocity in sediment to that in the bottom 

 water is 1.02; the density of the surface sediment is es- 

 timated to be about 1.6 gr/cc; the attenuation of sound in 

 the surface sediments (from in situ meter is 15.3 dB/ft 

 at 18.3 kc." 



Notes: 



(1) In the same message it is understood that a new point 

 is being reported when the letter "A" appears again (or 

 "B" or "C," depending on the line). 



(2) It is planned to report one whole line when the work is 

 done on that line. 



(3) A series of "A's" and "T's" will give relief along the 

 track. 



51 



