Gallagher 



to test the effects of changing sound velocity values on the values of acoustic 

 reflection coefficients obtained over a broad range of incident angles. 



DISCUSSION 



Two dissimilar sediment deposltional areas were considered. The sediments 

 in theslow depositional area, the Hatteras Abyssal Plain (HAP), are character- 

 ized by fine grained particles, low carbonate content, and high porosity. 

 Sediments in the rapid depositional area, the Tongue of the Ocean (TOTO), are 

 characterized by medium sized particles, high carbonate content, and moderate 

 porosity. Two cores from each area were investigated. The distance between 

 the two cores in both the HAP and TOTO areas is 0.4 mile. 



Variations in sound velocity are provided by values computed from Sutton's 

 regression equation and from direct laboratory measurements on the core samples. 



HATTERAS ABYSSAL PLAIN (HAP) 



These variations are strikingly evident in core no. l,as seen in Table 1. The 

 measured velocities for core no. 1 should probably be viewed with caution since 

 they are considerably higher than what the accepted sound velocity versus 

 porosity curves indicate; the porosities lie in the 70 percent range. It is possible 

 that a constant error existed in the laboratory measurements. However, the 



Table 1 



MEASURED AND SUTTON DERIVED SOUND VELOCITIES AND CORRESPONDING 

 ACOUSTIC IMPEDANCE DATA — CORE NO. 1— HAP 



92 



