ment texture from the top to the bottom, and 

 every core sample contains small amounts of 

 gravel and bioclastic material. The longitudinal 

 sections of the cores which w^ere examined 

 aboard the ship showed a sharp demarcation in 

 color and rigidity between 5 and 10 cm from 

 the top. The top 5 to 10 cm portions of all 

 cores were light olive-green and relatively soft, 

 whereas all the sediments below 10 cm were 

 dark olive-green with irregular black streaks 

 and patches and were tough. Some of the lower 

 portions gave out an odor of H.S. On closer 

 scrutiny it was noted that in almost all cases 

 decomposing worms were surrounded by large 

 black patches. Presumably, the sharp demarca- 

 tion in the sediment core color is related to 

 abrupt vertical changes in the oxidation- 

 reduction potentials along the core, and the 

 black patches represent some stage of hydro- 

 troilite precipitation. The oxidizing nature of 

 the core tops seems to be substantiated by the 

 fact that the habitation of marine macrobenthic 

 fauna was confined to the relatively lighter 

 colored top portions. 



The results of the grain-size distribution of 

 the Point Lay barrier beach deposits are 

 graphically represented in figure 3, and the 

 grain-size parameters are given in table II 

 (appendix A) . Generally speaking, the analysed 

 sediments consisted of well-rounded, mod- 

 erately well to very poorly sorted sandy 

 gravels, with distinct bi- to polymodal distribu- 

 tions. The mean size ranged from fine to coarse 

 gravel. These sediments have size distributions 

 which ranged from nearly symmetrical to very 

 coarsely skewed and mesokurtic to leptokurtic. 

 Texturally, there is a great similarity between 

 the sediments of the Point Lay barrier beach 

 and the sediments collected from the barrier 

 beaches around the Colville Delta-Prudhoe Bay 

 complex. The latter suite of samples was an- 

 alysed in a separate study funded by the 

 E.P.A. and the N.O.A.A.-Sea Grant (Naidu 

 et ah, 1970) . It is of interest to note that every 

 one of the barrier beach samples contained 

 several gravel-size anthracitic coal pieces. 



Clay Mineral Analysis 



The types and abundance of clay minerals in 

 the less-than-2 \i fractions of the sediment 

 samples are presented in table III (appendix 

 A), and their distributions are illustrated in 



figures 4, 5, 6, and 7. In all samples illite is 

 the predominant clay mineral, with weighted 

 peak area (Biscaye, 1965) ranging from 50.0 

 to 63.3 percent. The next two minerals in the 

 order of abundance are chlorite and kaolinite, 

 respectively. Smectite eitner occurs in traces 

 (less than 1 percent) or in small amounts (less 

 than 10 percent) . 



The patterns of distribution of clay minerals 

 (figs. 4, 5, 6, and 7) should be considered to be 

 tentative because they are based on a limited 

 number of sample analyses. However, some 

 very broad generalizations can be made from 

 the data obtained. It is of interest to note that 

 smectite occurs either in traces or is absent in 

 the nearshore environment. This is specially 

 true north of Point Lay. Any definite pattern 

 of distribution of kaolinite and illite, if present, 

 is not apparent at this stage of the study. There 

 seems to be, however, a marked concentration 

 of chlorite in the inshore shelf environment and 

 off the embayed region between Point Lay and 

 Cape Lisburne, a region, as mentioned earlier, 

 suspected to be the site of a gyre (Fleming 

 and Heggarty, 1966) . 



Comparison of the clay mineral assemblages 

 of the Beaufort Sea (Naidu et al, 1971) and 

 eastern central Chukchi Sea sediments brings 

 out some interesting diff"erences between the 

 two. Although sediments from both the seas 

 contain the same clay mineral assemblages, 

 some dissimilarities in the proportions of the 

 different minerals in the two regions are ap- 

 parent. For example, the kaolinite/chlorite 

 ratios in the eastern central Chukchi Sea are 

 relatively lower (avg. 0.4) than those in the 

 Beaufort Sea (avg. 0.7). However, the chlorite/ 

 illite ratios in the Chukchi Sea are relatively 

 higher (avg. 0.6) than those in the Beaufort 

 Sea (avg. 0.4). 



Geocheynistry of Sediment Interstitial Waters 

 The concentrations of various ions in the 

 interstitial waters from cores are presented in 

 table I (appendix A) and figures 8 and 9. The 

 cationic concentrations vary from horizon to 

 horizon within individual cores and also be- 

 tween cores. The relative concentrations of ions 

 of the interstitial waters are similar to but 

 slightly higher than normal sea water. Gen- 

 erally, the total concentration of the several 

 ions increases with depth in the core. 



175 



