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This is their specific interest. The Alaska Bering Sea Continental 

 Shelf area is tremendous, a large percentage of our total Continental 

 Shelf area. It will be many, many years before we can completely 

 describe that area with adequate hydrographic surveys with the 

 resources and ships that we have available. 



Mr. Pollock. Mr. Chairman, I apologize for being so parochial but 

 this is an area that is of vital interest to all of the United States. It 

 is a vast area with tremendous potential. I have no further questions. 



Mr. Rogers. Dr. White, what is the extent of the Continental Shelf 

 on the east coast and west coast in terms of distance, generally 

 speaking ? 



Dr. White. Could you comment, Admiral ? 



Admiral Jones. On the east coast the Continental Shelf averages 

 about 100 miles in width. On the west coast the shelf is much narrower, 

 averaging 30 to 40 miles except the vast shelf areas between Alaska 

 and Siberia. 



Mr. Rogers. And what depth ? 



Admiral Jones. As the Continental Shelf descends slowly seaward, 

 there is an abrupt change in the bottom slope marking the transition 

 from Continental Shelf to continental slope. This transition area is 

 called the shelf break. It occurs at a depth of 165 feet off the southern 

 tip of Florida, but is found at a depth of 395 feet off New England. 



Mr. Rogers. What would be the greatest depth ? 



Admiral Jones. Of the Continental Shelf ? 



Mr. Rogers. Yes, on the west coast. 



Admiral Jones. Conventionally the Continental Shelf is referred to 

 that area within the 200 meter or 100 fathom depth curve. The depth 

 of the shelf break on the west coast varies considerably. At Santa 

 Barbara it is about 100 meters — 330 feet. At other locations it is much 

 deeper. The world average is generally accepted as about 200 meters. 



Mr. Rogers. Is this still the definition of the Continental Shelf, the 

 200-meter depth? 



Admiral Jones. Yes. Outside of that general depth the continental 

 slope normally goes off at a much steeper rate into the deeper areas 

 of the ocean. 



Mr. Rogers. Roughly, how much of the Continental Shelf is mapped 

 now? 



Admiral Jones. I would say probably 80 percent of our Continental 

 Shelf has been covered by hydrographic surveys for nautical chart- 

 ing. These surveys provide the information for bathymetric mapping 

 of the Continental Shelves; however, many of these surveys are con- 

 sidered inadequate for bathymetric mapping because they were com- 

 pleted before the advent of echo sounders and electronic position-find- 

 ing equipment. 



Mr. Rogers. Are we in the process now of doing a mapping job on 

 the east coast of the Continental Shelf ? 



Admiral Jones. Yes; we are in the process of upgrading surveys, 

 many of them completed in the 1880's. We are trying to upgrade these. 



Mr. Rogers. What cooperation do you get from the oil companies ? 

 I presume the oil companies have done a great deal of mapping. 



Admiral Jones. Most of their hydrographic operations are in 

 greater detail than is needed for nautical charting and they do inten- 

 sive geophysical operations as well. 



