Figure 6. — Average percentage of digestible organic materials in sediments. 



temperatures reach 17°C at the outer edges of the apex. Bottom 

 water temperatures remain relatively unchanged at <6°C in the 

 shelf valley. Surface temperatures reach their annual maximum 

 value of about 26°C in August and bottom temperatures also show 

 a steady rise to = 10°C in the shelf valley. Surface cooling during 

 early autumn begins to break down the summerthermocline. By the 

 end of October, surface temperatures have dropped to = 16°-18°C 

 over much of the apex, while heat loss and vertical overturning 

 increase the bottom water temperatures to = 12°C inside the shelf 

 valley. Vertical mixing down to about 30 m is usually complete by 

 early or mid-November when water temperatures are 12°-14°C. 

 Bottom temperatures attain their annual maximum in this period. 

 Vertical mixing continues through December and surface and bot- 

 tom temperatures decline and approach their winter minima (Bow- 

 man and Wunderlich 1976; Bowman 1977). 



The dominant bottom feature of the New York Bight is the Hud- 

 son Shelf Valley, apparently cut by the ancestral Hudson River dur- 

 ing times of low sea level. The center of the Christiaensen Basin 

 (the landward terminus of the Hudson Shelf Valley Channel) is a 

 natural collecting area for fine grained sediments. The apex outside 

 the Christiaensen Basin is floored primarily by sand ranging from 

 silty fine to coarse with small areas of sandy gravel, artifact gravel, 

 and mud. In deeper water, in the Hudson Shelf Valley, where wave 

 action is less pronounced, silt is the dominant sediment (Williams 

 and Duane 1974; Freeland et al. 1976). Figure 5 shows mean grain 

 size of sediments in the apex. 



Figure 8. — Average concentrations of copper in New York Bight apex sedi- 

 ments. 



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Figure 7. — Average concentrations of chromium in New York Bight apex sedi- 

 ments. 



