STRATIGRAPHY OF THE DEEP-SEA FLOOR 79 



clay-shale section, it required about 2780 m of material to con- 

 solidate to the present average thickness of 1203 m. 



In the northwest Atlantic abyssal plain, Ewing and Ewing 

 (1959) record a first layer thickness of 440 m (velocity 1.62 km/ 

 sec) overlying a second layer of 1090 m thickness with a velocity 

 of 1.82 km/sec at the top of the section. If this is a clay-shale 

 section, it took about 3690 m of original deposits to consolidate 

 to the present thickness of 1530 m. 



The hypotheses, calculations, and measurements previously 

 discussed allow some generalized calculations of the amounts of 

 solid materials at any specific locality. If a general assumption is 

 made that the average porosity of all the original deposition was 

 70% (or 30% solids), then the following amounts of solids would 

 be present in the sections just discussed: 



1. In the western Atlantic (at The Lamont Observatory, see 

 Fig. 11, stations G-10, 12, and 13), where the total sediment col- 

 umn averages 1203 m thick, and calculations predict a total 

 amount of deposition of about 2780 m, there would have been 

 about 840 m of solids in the section. 



2. In the northwest Atlantic abyssal plain where the sediment 

 section is 1530 m thick, there should have been about 3690 m of 

 original deposits; here the solids should total more than 1100 m 

 in thickness. 



It can be seen that, even with a conservative estimate for the 

 amounts of solids in the original section (30%), the total amounts 

 of solids in the layers above the basalt, for these areas, fall close 

 to the estimated thickness of solids (1 to 3 km) postulated by 

 Kuenen (1950) and Revelle (1954) as necessary to supply the 

 materials indicated for the geochemical balance. 



Ages of Ocean Basins 



Obviously we have here an interesting method of estimating 

 ages of ocean basins if only valid rates of deposition were avail- 

 able. Broad generalizations about ancient rates of deposition in 

 the deep sea have little validity at the present time, but it is ap- 



