Ex: T1500 = sediment thickness 1500 feet over 

 prominent reflector. 



Note: When data are given at two points, 

 it is understood that conditions be- 

 tween the points are the same, or 

 changing in a regular manner. Ex- 

 amples: A67T300A75T500, means 

 that the reflecting surface is 

 dipping regularly toward the second 

 point. A91TRA110TR means that 

 rock is at the surface between 91 

 and 110 miles. 



4. Roughness of basement. 



Given by a series of "A's" and "T's." 



5. Sediment type (using API-Shepard (1954) diagram). 



"S" followed by one digit 



0-gravel; 1-sand; 2-silty-sand; 3-sandy-silt; 4-silt; 

 5-sand-silt-clay; 6-clayey-sand; 7-sandy clay; 8-clayey- 

 silt; 9-silty-clay; 10-clay; 11-glacial marine (mixture 

 of various types above); 12-rock; 13-silty-sand, or 

 sandy-silt with abundant shell fragments. 



6. Sound velocity in sediments (measured in situhy 

 diver-handled probes). 



"V" followed by three digits; Ex: V515 means velocity 

 is 5150 ft/sec (this gives it to nearest 10 feet/sec). 



7. Ratio of sound velocity in sediments/sound velocity in 

 bottom water. 



"P" followed by three digits with decimal understood 

 between 1st and 2nd digit. Ex: P103 means vel. in 

 sed/vel. water = 1.03 



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