Table 5 



OFFSHORE MINING OPERATIONS IN 1967 



UNCONSOLIDATED DEPOSITS 



Source: Charles M. Romanowitz, Michael J. Cruickshank, and Milton P. Overall, "Offshore Mining Present and Future,' 

 presented at NSIA/OSTAC Ocean Resources Subcommittee Meeting, San Francisco area, April 26, 1967. 



areas at various depth levels anywhere from the 

 present 1 60-meter line to a little above the present 

 shoreline. With the post-glacial rise of sea level that 

 accompanied the melting of the glaciers, the 

 ancient beaches and river channels, which in places 

 contain valuable placers, were submerged and may 

 have been buried by still younger sediments. In 

 some shallow water areas, however, there are 

 offshore placers related to bottom topography and 

 offshore currents rather than to beach or alluvial 

 processes. 



Nevertheless, the placers in the marine environ- 

 ment are mainly confined to the inner edge of the 

 continental shelves, and it is unlikely that signifi- 

 cant placer deposits will be found on the conti- 

 nental slope or beyond. 



Several good prospects for the development of 

 placers exist on the shelves of both the east and 

 west coasts of the United States. None is now in 

 production and all are low grade, but they have 

 sufficient potential value to warrant further pros- 

 pecting and improvement of mining technology. In 

 general, the composition of mineral assemblages of 

 east coast placers differs from that of west coast 

 placers although there is some overlap. The follow- 

 ing tabulation from Overstreet'^ is indicative of 

 the valuable minerals that might be expected in 

 the two regions: 



In McKelvey et al., "Potential Mineral Resources of 

 the United States Outer Continental Shelves," unpub- 

 Ushed report of the Geological Survey to the Public Land 

 Law Review Commission, March 1968. 



VIM 03 



