metallic vein deposits. Sulphur is being recovered 

 from offshore salt domes in the Gulf of Mexico, 

 and coal has been mined off the coasts of Canada, 

 the United Kingdom, Japan, and Taiwan, either 

 through inclined access tunnels driven from shore- 

 based coal mines or from vertical shafts drilled 

 through artificial islands constructed in the sea. '* 

 Iron ore deposits of commercial grade are known 

 in the shelf area of the Gulf of Finland and off the 

 coast of Newfoundland. Tin deposits probably 

 extend into the shelf off the coast of Cornwall in 

 the United Kingdom. 



Metallic vein deposits are commonly associated 

 with intrusive igneous rocks. Although the shelves 

 and slopes are composed dominantly of sedi- 

 mentary rocks, igneous rocks are known in three 

 areas on the continental shelf of the United States: 

 the Gulf of Maine, Monterey Bay, and off the 

 Golden Gate in California. '^ Samples from these 

 areas have not shown valuable mineralization. 

 Nevertheless, onshore lode or bedrock deposits are 

 sufficiently abundant nearshore in Alaska, the 

 west coast states, and the New England states to 

 suggest the possible presence of offshore deposits 

 of similar character in rocks of the shelf. 



It is evident from the foregoing pages and from 

 the data in Appendix A that our knowledge of the 

 hard mineral potential of our continental shelves 

 and slopes is very slight. Bathymetric mapping and 

 charting and geologic analysis are needed. 



Bathymetric charts showing the contour of the 

 sea floor are, like topographic maps on land, the 

 base on which many other types of information 

 are plotted. It is essential that good bathymetric 

 charts be available if other information, such as 

 distribution of geologic formations and structures 

 and delineation of mineral deposits are to be 

 analysed and interpreted in a meaningful way. 



Recommendation: 



Bathymetric charts at 1:250,000 scale should be 

 completed for the entire U.S. continental shelves 

 and slopes within IS to 20 years by a Govenmient 

 agency (ESSA). Reconnaissance gravity and mag- 

 netic surveys, and continuous seismic profiling 

 surveys can be run concurrently with the bathy- 



'^ United Nations Economic and Social Council, Re- 

 sources of the Sea: Part 1, Mineral Resources Beyond the 

 Continental Shelf, report of the Secretary General, 

 February 1968 (E4449/Add. 1). 



Emery. 



metric and routine oceanographic surveys. Gravity, 

 magnetic, and seismic maps of the shelves and 

 slopes at 1 : 250,000 scale should be completed in 

 about 15 to 20 years. Cost of the total program is 

 estimated at $225 to $250 million. The bathym- 

 etry, gravity, magnetic, and seismic mapping pro- 

 gram should be closely correlated with the priority 

 requirements of the geologic analysis program. 



An understanding of the geologic structure and 

 composition of the continental shelves and slopes 

 is necessary to appraise the resource potential of 

 this vast area. Such an understanding will also aid 

 in determining favorable target areas for mineral 

 resources, provide a basis for wise management of 

 the offshore resources, enhance our understanding 

 of geologic processes that form ore deposits, assist 

 in the selection of safe sites for underwater 

 installations, and help planners in making wise 

 decisions involving multiple uses of the estuaries 

 and shelves. 



Reconunendation: 



A geological map and three-dimensional analysis of 

 the continental shelves and slopes should be made 

 at 1:250,000 reconnaissance scale. The mapping 

 and analyses would use as bases the bathymetric 

 maps and would utilize the gravity, magnetic, and 

 seismic data from the surveys previously recom- 

 mended; bottom sampling; examinations of out- 

 crops by submersibles and other means; and 

 additional geophysical studies, such as aeromag- 

 netic surveys and seismic profiling for deep struc- 

 tural information. In addition, acquisition of the 

 necessary information for three-dimensional analy- 

 sis will require drilling shallow holes (less than 50 

 feet deep) and approximately 100 deeper holes 

 (500 to 5,000 feet) in imdeveloped areas. 



Studies at scales of 1:62,500 and larger will 

 probably be needed in geologically critical areas. 

 The total 1:250,000 scale reconnaissance program 

 should be completed in 20 years. This program can 

 best be carried out by a Government agency, but 

 non-proprietary information available from private 

 industry should be utilized to the fullest extent 

 possible. The geologic analysis program will re- 

 quire the control of ship facilities which preferably 

 should be provided by other Govenunent agencies 

 so that the agency conducting the program would 

 not have to acquire its own vessels. 



Research on geologic and hydrologic processes 

 that form and modify the earth's crust should be 



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