oceanographic, physical oceanographic, chemical oceanographic, biological 

 oceanographic, and surface phenomena are investigated. To facilitate the 

 initial search for information, Tables A-1 to A-8 of Appendix A have been 

 prepared. These tables list possible sources of specific information in these 

 categories. 



Table A-1 is a listing of possible sources of bathymetric charts. From 

 these charts, candidate sites can be chosen according to the requirements of 

 the particular structure — for example, placement in a relatively flat location 

 or placement on a topographic high. Another reason for investigating existing 

 bathymetric charts is to determine if these bathymetric charts are sufficiently 

 accurate for the requirements of the structure or if additional data are required 

 from the detail survey phase. 



Table A-2 lists possible sources for underwater photographs that could 

 be used in the preliminary survey phase. The purpose of locating and studying 

 available photographs is to determine if particular sites contemplated for a 

 structure are suitable and if additional photographs are required from the 

 detail survey phase. A number of conclusions can be reached by studying 

 these existing photographs. For example, as shown in Figure 6, it is seen that 

 considerable biological activity is taking place at the sediment surface, thereby 

 disturbing the upper layers of the sediments. Placing, leveling, and stabilizing 

 a structure on rock outcrops such as that shown in Figure 7 would be very 

 difficult; thus it may be desirable to avoid these areas initially. The lack of 

 sediments on the rock outcrop of Figure 8 could be indicative of high currents 

 in the area. If it is suspected that certain local seafloor areas such as estuarine 

 outlets (that is, Mississippi River) possess a uniform gradation from clear water 

 to consolidated sediments (that is, clear water, milky, turbid, colloidal, etc.) , 

 photographs could verify or may show that this is not a problem, as is shown 

 in Figure 9 for an area off San Diego. Other important features such as tension 

 cracks and slide debris may possibly be recorded on existing photographs. Thus, 

 depending on the particular structure to be founded on the seafloor and its site 

 requirements, existing photographs can be advantageously interpreted. 



Sediment samples for geological and engineering properties have been 

 taken from various ocean-floor sites. Particular information on specific sites 

 will be valuable in the preliminary survey phase. Possible sources of this 

 particular information are listed in Table A-3. Although much information 

 on these properties is being published, the majority of the data have received 

 only limited dissemination. It is necessary that these data be searched out to 

 determine if additional data are required for these properties in the detail sur- 

 vey phase. 



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