future. There is a possibility of finding eco- 
nomically attractive deposits of finely divided 
metal sulfides that were formed in place on the 
continental slope. 
6. Southwest Pacific Coast—know deposits of 
sand, gravel, and phosphorite. 
7. Northwest Pacific Coast—Outer Continental 
Shelf off northern California and Oregon is 
known to have modest placer deposits of gold 
and other heavy metals. 
8. Great Lakes—although not Outer Continental 
Shelf lands, the portion of the lake beds within 
the United States are known to have manganese 
and copper ore deposits. 
9. Bering Sea—-Outer Continental Shelf has the 
most promising potential for mining and hard 
minerals of all U.S. Outer Continental Shelf 
waters. Placer deposits of this potential include: 
gold, platinum, cassiterite (tin), scheelite (tung- 
sten), rare earths, ilmenite (titanium), and 
others. Lode deposits are likely to include 
barite and copper, lead and zinc (as sulfides), 
and molybdenum, while deposits of chemical 
precipitates of uranium-bearing minerals are 
probable in some anoxic sites. Government, in- 
dustry, and academic groups have been making 
hard mineral surveys for more than 10 years. 
10. Arctic Shelf—largely of unknown potential, 
but drainage from metal-bearing provenance 
rocks probably washes some noble metals into 
Outer Continental Shelf high-energy sand sites. 
11. Insular States and Territories—although few 
mineral surveys have been made in the Outer 
Continental Shelf or its equivalent waters off 
American Samoa, Puerto Rico, Hawaii, or the 
Trust Territories, the potential for volcanic and 
basalt-related minerals and manganese crusts 
appears likely. 
Environmental Impact and Conflict With Other Uses 
Potential pollution from marine mining operations 
depends on both the mining methods and the specific 
environmental conditions of the operation. Generali- 
zations based on either a commodity or a location by 
itself could be misleading. Apart from some broad 
guidelines, assessments of potential pollution from 
marine mining must be operation- and site-specific. 
Potential environmental effects from production 
activities at sea are of three general types: alteration 
of the shape of the sea floor, interference with other 
uses of the area, and disturbance of marine eco- 
systems. The present use of trailing suction hopper 
dredges for sand and gravel mining, for example, 
causes a general lowering of the scabed over the 
area of the deposit to a maximum of about 5 meters. 
Stationary dredges as now used, mostly for sand, 
leave a hole in the seabed up to 20 meters deep and 
80 meters in diameter. In both instances, there is a 
release of fine-grained solid materials into the water 
near the dredge, either from perturbation of the 
seabed by the dredgehead or from overflow of the 
hopper. The release of toxic substances into the 
water is not a general feature of sand and gravel 
dredging. 
Dredging may change the shape of the seabed 
sufficiently to alter local wave and current patterns. 
This could lead to local changes in coastal erosion 
or deposition and could cause destruction of beaches, 
siltation of harbors, removal of offshore banks, or 
disruption of longshore sand transport systems within 
the immediate area. Such impacts as a result of 
mining on the Outer Continental Shelf are unlikely. 
Experience in Europe and elsewhere has shown 
that mining operations can be hazardous to other 
marine activities or emplacements, causing collisions 
in shipping channels, disturbdnce of navigational 
buoys or anchorages, and cutting or displacing 
buried cables or pipelines. Fishing activities have 
been disturbed by the creation of obstructions to 
bottom trawls, particularly where deep pits have 
been excavated in fishing grounds or large boulders 
have been exposed by removal of the surrounding 
substrate. In some areas, illegal dredging has al- 
legedly destroyed maricultural nursery grounds. 
The potential impact of marine mining on eco- 
systems is the least known area of environmental 
problems, and without doubt, the most difficult one 
to assess. For the most part, effects are secondary 
and due to some alteration in the existing physical, 
chemical, or trophic equilibrium. Impacts on the 
coastal zone tend to be more significant than those 
on the Outer Continental Shelf because of the 
higher physical and biological energy levels generally 
recorded there and the proximity to population cen- 
ters. Physical changes that may induce biolegical 
effects include variations in temperature, current 
patterns, amounts of suspended particulates present, 
nature of the sea floor and substrate, light penentra- 
tion and photosynthesis, and the introduction of new 
habitats. Significant chemical changes may be caused 
by the presence of nutrients, trace elements, or 
toxics. Possible changes in the food chain include 
removal of, or influence on, existing species by in- 
volving them in the dredging operation. In general, 
alterations in temperature and chemistry are unlikely 
and would occur only as a result of induced changes 
in current patterns near shore, where there were 
very significant gradients of local temperature and 
chemicals. 
Analyses of the potential impacts require a knowl- 
edge of the undisturbed populations and their nat- 
ural cycles to that changes can be predicted, verified, 
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