tially at this time and projections are that with the 

 exception of sand and gravel it is not likely to do 

 so in the near future. Chief industries at this time 

 are: 



-Sand and gravel. Production of sand and gravel 

 from marine deposits is not reported separately by 

 the U.S. Bureau of Mines, but is estimated at 

 roughly $15 milhon annually. 



Plentiful deposits are available on land and can 

 be worked with a small investment, but the cost of 

 transportation is a large part of the selling price, 

 and the product is used mostly in urban centers. 

 With the growth of our cities, and the zoning out 

 of nearby gravel pits, the shorter haul with cheaper 

 sea transportation from offshore sources make 

 them increasingly attractive and it can be expected 

 that growth of this industry will accelerate. 



—Oyster shell. Production remains approximately 

 constant at an estimated $30 million annually. The 

 product is used for aggregate in concrete and road 

 material in the manufacture of portland cement 

 and lime, and for poultry grit and fertiUzer 

 additives. Although ample deposits exist, those 

 nearer the market are gradually being depleted, 

 and the increased transportation costs in working 

 more distant deposits will raise the market price. 

 Total production is not expected to increase 

 substantially. 



—Other minerals. Only very limited sampling 

 operations have been conducted for other minerals 

 and there is no production as yet. 



Phosphorite deposits of considerable extent 

 have been explored along the southern CaUfornia 

 coast and the coasts of North Carolina, Georgia, 

 and Florida, but it does not appear that they can 

 be mined profitably in competition with amply 

 available sources on land. 



—Heavy metals. Gold, tin, and platinum have not 

 been produced from the U.S. shelf except for 

 minor amounts during sampUng operations. During 

 1966 two U.S. companies undertaking offshore 

 gold-bearing placer exploration in Alaskan waters 

 decided to discontinue their efforts, but a third 

 was sufficiently encouraged by results of its 1966 

 pilot production to resume in 1967. 



The marine mining industry faces the same 

 problems described in the preceding section. In 



some instances such as oyster shell dredging in 

 Texas the conflicts with neighboring fishing indus- 

 tries are severe. In Maryland, however, where 

 management is under a single State agency, oyster 

 shell dredging is regulated and conducted without 

 conflict. 



XI. NAVIGATION AND SPATIAL CONFLICTS 



Ship collision is neither a new problem nor is 

 the frequency projected to increase. On the 

 contrary, although ship tonnage is predicted to 

 increase, the actual number of ships may decrease 

 and improved safety equipment should result in 

 fewer collisions. A significant consideration, how- 

 ever, is the increasing size of ships. Further, 

 because of the exotic and often hazardous nature 

 of the cargoes, the consequences of a collision or 

 grounding become increasingly serious. 



High traffic density occurs: 



—Where ships alter course to round a headland and 

 are hkely to keep the same distance offshore. 



—Where traffic is confined to a narrow strait, e.g., 

 the Strait of Florida, through which pass about 

 150 ships per day. 



—In the approaches to large ports, e.g.. New York, 

 where about 70 large ships per day enter or depart. 



A more recent navigational problem has re- 

 sulted from offshore oil installations, the outstand- 

 ing example being the Gulf of Mexico. Here there 

 are about 6,000 oil or other platforms offshore, 

 with about half in or near shipping lanes. The daily 

 deep draft traffic out of Gulf ports is over 300 

 vessels, and over 50 collisions have occurred since 

 1960 between ships and structures. Pipelines pres- 

 ent added problems to fisheries and anchorages. 



Installations may be outside shipping lanes and 

 still cause interference with navigation. Off the 

 Port of Galveston, a ship lost 37 hours anchored in 

 fog because its radar could not differentiate 

 between the sea buoys leading into the port and 

 nearby oil installations. Off New Orleans ships 

 have had difficulty in locating by radar the key sea 

 buoy marking the channel entrance because it was 

 hidden by an oil installation.^^ 



W. L. Griffin, Accommodation of Conflicting Uses of 

 Ocean Space with Special Reference to Navigation Safety 

 Lanes, Second Annual Law of the Sea Institute, Univer- 

 sity of Rhode Island, June 1967. 



III-2S 



