LOCAL VARIABILITY IN MARINE SEDIMENTS 725 



The coe fficien t of sorting, i.e., the log of the geometric quartile deviation 

 (logx/Qg/Qi), which is indicative of the sorting of the sample, differs 

 by a factor of 1.23. They are all normally sorted sediments ranging 

 from a sorting coefficient of 0.428 to 0.528. 



Visual inspection of 1P2 (Fig. 4), shows two fairly well matched 

 bimodal curves. The cumulative curves also approximate one another. 

 The median diameters differ by 0.29 mm.; both are poorly sorted with 

 coefficients of 1.088 and 1.100. 



Sample 7M1 (Fig. 5) is located on the west slope at a depth of 

 about 500 feet. The frequency curves for the three adjacent cores are 

 similar; however core A has a mode between 0.125 and 0.065 mm., while 

 cores B and C have their modes between 0.065 and 0.031 mm. The me- 

 dian diameters are essentially the same, with only a 0.03 mm. difference. 

 The most striking feature is shown in the numerical value for the sort- 

 ing; 0.139 for core A and 0.385 for core B. They differ by a factor of 

 2.87, yet they all represent good sorting. All three cores are generally 

 comparable. 



Sample 3P3 (Fig, 5) shows some divergence between the three ad- 

 jacent cores. There is a 10 percent difference in the frequency of the 

 major modes. Cores A and B have modes between 0.5 and 0.25 mm. 

 while core C has a mode between 0,125 and 0.0625 mm. This represents 

 a difference of two standard grade sizes. The medium diameters have 

 a maximum difference of 0.34 mm., or vary by a factor of 3.10. Sorting 

 is essentially normal in all three cores with coefficients ranging from 

 0.431 to 0.597. 



Sample 5L2 (Fig, 6) from the east slope at a water depth of 700 

 feet shows a marked visual difference. Core A is bimodal while Core B 

 is unimodal. The median diameters and the coefficients of sorting dif- 

 fer by factors of 1.8 and 1.32 respectively. Core A is poorly sorted and 

 core C is normally sorted. 



Sample IPl (Fig. 6) taken from the east slope at a depth of ap- 

 proximately 500 feet shows a striking variation between adjacent cores. 

 Core B is definitely unimodal, with the mode between 0.5 and 0.25 mm. 

 Core C is slightly bimodal with the major mode between 16 and 8 mm. 

 The median diameters differ by a factor of 1.8; the coefficients of sorting 

 by a factor of 1.68. Both are poorly sorted. 



The horizontal variation of the median diameters of the particles 

 at particular depths in the cores is shown in Figure 7, Sample P6 shows 

 a good relationship with depth between the median diameters of the 

 three adjacent cores. The remaining samples present varying degrees of 

 divergence in the median diameters. 



