Excluding zones of turbidite occurrences, cores from throughout the cul-de-sac are 

 similar in texture and color to near-flank cores, and the portion of these cores attrib- 

 utable to pelagic type sedimentation is strikingly similar to the near-flank area. The 

 top 2 or 3 centimeters of almost all cul-de-sac cores show an orange-red hue which 

 is indicative of oxidizing conditions at the surface and which is absent throughout the 

 remainder of the sediment with depth. Core 62-46 contains a very coarse zone unlike 

 a typical turbidite in that the zone shows no grading but consists of a reef detritus 

 where both the top and bottom contact with the enclosing sediment is sharp. This 

 particular sequence is probably the result of sand "falls" over the bank edges rather 

 than turbidity current deposition. 



Particle Size: Silt is the dominant size fraction in this area as well as the 

 remainder of the TOTO; however, the increase in turbidites compared to the axial 

 area raises the percentage of sand by a slight amount. The graded nature of turbidites 

 is apparent in cores 62-42 and 61-16 (Fig 9) where a decrease in median grain diameter 

 upwards in turbidite zones in the core is observable. The average size distribution of 

 the samples analyzed is 20 percent sand, 29 percent silt, and 51 percent lutite. 



Poor sorting is prevalent among these sediments, although a few of the samples 

 analyzed from the bottom of the coarser turbidites show almost perfect sorting. Skew- 

 ness values are not much different than the axial sediments in that the majority of 

 samples are positively skewed with a few negative values present (Table V). 



Constituents : Constituents comprising the cul-de-sac sediments are not unlike 

 the other areas of the channel. Turbidites, however, contain a greater percentage 

 of reef-derived material, and oolites and oolith-like particles constitute a major 

 portion of the reef detritus. Plant debris is more prevalent throughout cul-de-sac 

 sediments than in the axial area, and several turbidites contain thin zones of this 

 fibrous material incorporated into the sequence. 



Organic Carbon : Organic carbon content of the sediment in this area is the 

 highest encountered in the channel and is probably due to the increase in plant 

 detritus. Surface values of organic carbon are as high as 2.00 percent and decrease 

 in the channel. 



Mass Physical Properties : Sediments in the cul-de-sac are less dense and contain 

 a higher water content than any sediments in the TOTO, and, in like manner, void 

 ratio and porosity values are also highest. Although the water content shows a de- 

 crease from top to bottom in the cores, there are interruptions in a uniform decrease 

 with depth which are probably due to the large amounts of coarse-grained turbidites 

 present. The turbidites, being more pourous, are capable of holding greater water 

 content than the fine-grained material above and below. 



As in the other TOTO cores, sediment density generally Increases while void 

 ratio and porosity decrease with depth in the sediment. 



38 



