(a) Grain-size analysis was performed by sieving a dried sample 

 aliquot through a series of 20-centimeter-diameter nested sieves of 1-phi 

 mesh intervals (Wentworth scale) for 30 minutes. The sample was first 

 rinsed with distilled water to remove salt and sieved wet with a 0,063- 

 millimeter mesh to remove any silt-clay fractions (also dried and weighed) . 



'(b) Organic carbon present in each sample was determined by combusting 

 a previously dried sample at 500 Celsius for 1 hour. The loss due to 

 ignition was considered to be the organic ca.rbon content. 



(c) Carbon as present in carbonate compounds was determined by heating 

 a sample (organic carbon previously burned off) to 1000 Celsius for 1 hour. 

 The weight loss was considered to be the amount of carbon, as carbonates, 

 present in the sample. 



Various data analysis procedures were used in the statistical analyses 

 (Tables 1 to 4) of the sediment samples. Organic carbon and carbonate values 

 were calculated and presented as percentages of the total sample. Statistics 

 on the grain-size distribution were performed using the following formulas, 

 where phi (0) = -log2x; x = particle size in millimeters: 



(a) Median grain size, Md , is the point at which half of the 

 particles by weight are coarser and half are finer. It is the 

 diameter corresponding to the 50 percent mark on the cumulative curve. 



(b) Mean grain size, Mz, is the overall size measure (Folk, 1974). 



^^ ^ 016 + 050 + 085 



(c) Inclusive graphic standard deviation (sorting coefficient) , 

 o, is the measure of uniformity or sorting (Folk, 1974). 



_ 084 - 016 , 095 - 05 

 ° 4 6.6 



(d) Inclusive graphic skewness, Sk, measures the degree of asjomnetry 

 of the particle distribution curve, taking into account the skewness 

 of the tails of the curve as well as the central part. It is 

 independent of the sorting of the sample. A symmetrical curve has a 

 skewness of zero; a positively skewed curve indicates an excess of 

 fine material; a negatively skewed curve indicates an excess of 

 coarse sediments (Table 3) (Folk, 1974). 



ov = 016 +084 - 2050 , 05 + 095 - 2050 

 2 (084 - 016) "^ 2 (095 - 05) 



(e) Graphic kurtosis, Kg, is the ratio between the sorting in the 

 tails of the granulometric curve and the sorting of the new central 

 part of the curve (Folk, 1974). 



095 - 05 



Kg 



2.44 (075 - 025) 



