SURVEYING THE OCEANS (OCEANOGRAPHIC) 43 



Oceanographic Office is proceeding rapidly to map regional fea- 

 tures of broad expanses of the sea bed across more than ten 

 million square nautical miles of the North Atlantic and North 

 Pacific Oceans. Directed primarily to finding variations in 

 acoustic properties of the bottom, this program makes use of a 

 spectrum of observations to determine limits of the ocean's 

 physiographic provinces. Some 160,000 nautical miles of sub- 

 bottom profiles have been recorded already. These profiles are 

 examined in conjunction with concurrent geomagnetic observa- 

 tions, supplemented by analyses of ocean bottom cores ranging 

 to 30 feet in length. This information has provided a basic 

 understanding of the geologic history and structural processes of 

 the regions studied. Such understanding makes it possible to map 

 acoustic properties of the bottom by a sampling process far more 

 economical than the detailed survey that w^ould otherw^ise be 

 required. These sea-floor surveys, done from both Navy and 

 contract ships, are providing systematic information that not 

 only is vital to Fleet operations but also will be highly significant 

 to future minerals search and exploitation operations. 



CURRENTS 



Naval interest in ocean currents traditionally has centered on 

 their navigational effects. Navigators' reports of set and drift, 

 accumulating by the thousands since Maury's initiation of the 

 program, have outlined the general trends of the major surface 

 currents. Such reports continue to be made to the Oceanographic 

 Office and are of value in helping to define seasonal variations 

 of practical interest to navigators, despite the relative crudity of 

 the observations. The coming of automatically recording current 

 meters attached to deep-moored buoy arrays has now made pos- 

 sible more precise measurements of currents at the surface and 

 at depth. Deep currents can also be measured by meters hung 

 from drifting buoys or by neutrally buoyant targets tracked by 

 surface ship sonars. 



The Oceanographic Office measures oceanic currents either to 

 support specific operations, such as the Palomares bomb recovery, 

 or to help derive a better understanding of the dynamics of the 

 sea. The longer-range sonars now used by the Fleet are affected 



284-444 O - 67 - 4 



