78 



HISTORY OF THE OCEANS 



where 



and the porosity is: 



e = 



Volume of voids 

 Volume of solids 



V^olume of voids 

 Total volume 



In a paper on seismic refraction results in the Atlantic Ocean, 

 Ewing and Ewing (1959, p. 296) show three stations (Fig. 11) 

 in and near the abyssal plain (stations G-10, G-12, and G-13, 

 located in the area 25° 23' to 26° 25' X Lat, 67° 26' to 72° 02' W 

 Long; a\-erage water depth: 5.47 km). In this area there is an 

 average of 320 m of sediment (velocity 1.70 km sec) overlying 

 second layers with an average velocity of 2.16 km /sec (at the top 

 of the layer), and an average thickness of 883 m. These velocities 

 and thicknesses indicate a probable clay-shale section. If this is a 



-5.0 



G-13 



G-12 

 STATIONS 



G-IO 



WATER 



h» ' r 



■% 



-6.0 2 



"^- -T . ■. . ■.'.■.'-■.■.■- ...... .•.■.■.•.•.;.■..-.. /f 



UNCONSOLIDATED T SEDIMENT ... |jo^^^/SE;q.|90 m 



420 M ■■.■■■•••. ■•■.■■.:••. •.■■350 M .••.■....•.•.■.■.■.•.■.■.•■.•.■•: v^^^ 



I 70 KM/SEC ■.■-■■■ ■■■.■1.71 KM/SEC ••;__;■ Ji.-^ 2.46 KM/SEC 



1.99 KM/SEC 



2.03KM/SEC SEMICONSOLIDATED 



SEDIMENT 



7.0 H 



5 6.85 KM/SEC 



EC 

 600 M _ 



57 KM/SEC 



OCEANIC 

 LAYER 



6.90 KM/SEC 



WESTERN NORTH ATLANTIC 



LAT. 25°23'- 26*25' N 

 LONG. 67*26'- 72* 02'W 



DATA FROM 



EWING i. EWING (1959) 



NAUTICAL MILES 



Fig. 11. Seismic refraction survey results from the Western .■\tlantic Basin 

 (Ewing and Ewing, 1959). 



