Bathymetry and seismic refraction profile surveys of the North Carolina 

 coast and gravity surveys of the west coast Continental Shelf were also 

 conducted. 



Special geological and geophysical studies were made between Cape Hat- 

 teras and Cap Blanc, Mauritania, in support of the Trans-Atlantic Geo- 

 traverse (TAG), a seaward extension of the U.S. Transcontinental Geo- 

 physical Survey, and will provide a continuous crustal section completely 

 across a continent and an ocean basin. The TAG corridor is an approximate 

 200-mile-wide band between Cape Hatteras and Cap Blanc. In addition, 

 surveys were conducted in the Juan de Fuca Fracture Zone area to deter- 

 mine changes in magnetic characteristics. 



In the Navy, more resources are dedicated to deep ocean bathymetry 

 and geophysical data collection than to any other component of its survey 

 program. The high-priority areas which these surveys primarily support, 

 strategic forces and antisubmarine warfare (ASW), are global in extent. In 

 1971, over 500,000 track miles of precise bathymetric data, 250,000 miles of 

 shipboard gravity and geomagnetic data, and 150,000 miles of subbottom 

 seismic reflection profiling data were collected. This was augmented by 

 almost 100,000 track miles of airborne geomagnetic survey data collected 

 to define the residual magnetic anomaly field in support of ASW. The 

 Navy's eff"ort is receiving increased emphasis in 1972 through the replace- 

 ment of older ships and aircraft and the diversion of other ships to assist in 

 such surveys. 



Coastal Zone Mapping 



The coastal zone mapping effort includes metric aerial photography; 

 surveying and mapping for control of hydrography and maintenance of top- 

 ographic chart details, location of landmarks, and aids to navigation ; surveys 

 to delineate coastal inundation limits, coastal boundaries, and storm evacua- 

 tion routes; and advisory and technical services to States engaged in imple- 

 menting a coastal zone wetlands mapping program. There is also some 

 effort here to extend geodetic control seaward. 



Over 17,000 lineal miles of panchromatic, infrared, and color aerial map- 

 ping photography were flown in 1971, using wide-angle and super- wide- 

 angle single-lens precision cameras. About 120 shoreline maps and related 

 photogrammetric data were provided to support hydrography. A total of 

 330 charts and basic map drawings were corrected from new aerial photog- 

 raphy, including the compilation of topography for small-craft charts and 

 the location and verification of about 600 aids to navigation and 400 land- 

 marks. 



Federal, State, and private boundaries in the coastal zone must be 

 determined for the proper planning and management of the coastal zone 

 environment. In coastal areas, the mean high-w^ater line usually marks the 

 boundary between State and private ownership; the mean low- water lines 

 on the east and west coasts define the baseline from which seaward jurisdic- 

 tional boundaries are delineated, as, for example, the seaward boundary 

 between Federal and State jurisdiction over seabed resources. The equiva- 



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