222 



Sediments 



Table 15 



Percentage of Calcium Carbonate in Cores 



Depth of 13 to 38 cm 



Bottom of Core, 280 to 460 cm 





*• ».. ^ 



MEDIAN DIAMETER-MICRONS 



Figure 190. Plot of median diameter against Trask sorting 

 coefficient for sediments from mainland shelves, island 

 shelves, and bank tops (circles) and for sediments from 

 basin floors, basin slopes, and continental slopes (dots). 



sediments from basin floors and the latter 

 sediments from mainland shelves, island 

 shelves, and bank tops. Some overlap of 

 points is caused by coarse sediments that 

 have been carried from shelf areas by tur- 

 bidity currents and deposited in the basins. 

 Sediments from basin slopes and the conti- 

 nental slope (plotted as basin sediments in 

 Fig. 190) also tend to be concentrated in the 

 area of overlapping circles and dots of the 

 plot. The poorly sorted shelf sediments are 

 ones of mixed origin, most of them having 

 large percentages of coarse shell fragments. 



The relationship of sorting to median di- 

 ameter is somewhat similar to that discov- 

 ered by Inman (1949a) for beach sands, 

 wherein the best sorUng occurs for sands of 

 about 1 80-microns diameter and poorer sort- 

 ing is typical of both finer and coarser sizes. 

 In this plot, covering a much wider range of 

 sizes and types of sediment than beach 

 sands, the trends are not so clearly exhibited. 

 However, even casual examination of Figure 

 190 shows a definite difference between shal- 

 low and deep-water sediments that indicates 

 a difference in depositing agents. 



C. Depth and age distribution of calcium 

 carbonate. As shown by Table 15, cores 



