SEDIMENTCARPET 57 



middle one at 7,350 feet. The deepest, which is pre- 

 sumably reflected from the bedrock beneath the sedi- 

 ment carpet, indicates a total thickness of the latter of 

 no less than 1 1 ,600 feet, which is a record for the cruise. 

 These figures, quoted from Weibull's paper now being 

 published in the Reports of the Swedish Deep-Sea 

 Expedition, are liable to certain final corrections. One 



5t3/5 



Ch.3 



■^ 



iiiiiniiiiiiiiiiiiiiiiti 



Fig. 23. Diagram from Weibull's measure- 

 ment 



of them concerns the comparative difference in the 

 velocities of sound in sediment and water, the latter 

 figure, some 4,900 feet a second, having been used in 

 translating the time lag into sediment thickness. Ac- 

 cording to American authors who have been working 

 with a method to be described below, the velocity of 

 sound in sediments from the coastal shelf is 1 5 ^7 to 20% 

 greater than in water. Weibull, who is at present in- 



