Velocity of Current (knots) 

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£ 1,600 =• 



(= 2,000 



2,800 

 3,200 

 3,600 

 4,000 



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Figure 1. Design current velocity profiles. 



Ocean Bottom Conditions 



The topography of the ocean bottom to a depth of 6,000 feet includes 

 continental shelves, most of the continental slopes, shallow areas of mid-ocean 

 ridges, the borders of atolls and islands, and the tops of some seamounts. 

 Depths to 20,000 feet encompass the remaining portion of the ocean floors, 

 with the exception of deep ocean trenches and canyons, which may extend in 

 depth to more than 35,000 feet. The continental shelves vary from 60 to 

 1,800 feet in depth and from a scarcely measurable width to greater than 270 

 miles wide. The average slope of the shelf surface is 0°07', being somewhat 

 steeper over the inner than over the outer half. Valleys and canyons that cut 

 the continental shelf have slopes as steep as any on land. Shelf sediments are 

 primarily sands, with mud and gravel also common. Sediments of silty clay 

 with sand layers are found at the bottom of the shelf valleys or basins. Sedi- 

 ments of the continental slopes are less well known than those on the shelves. 

 These sediments have a low shear strength that ranges from 0.1 to 15 psi; an 

 average of 1 psi was considered representative. 



