OBJECTIVE FOUR - TO DESCRIBE THE SEA FLOOR AND TO UNDERSTAND ITS LONG- 

 TERM AND SHORT-TERM EVOLUTION; INCLUDING THE TOPOGRAPH!, GEOPHYSICAL 

 NATURE AND SUBSURFACE STRUCTURE WITH PARTICULAR INTEREST IN THE SKA 

 FLOOR'S RELATION TO THE SURROUNDING LAND MASSES 



Some of the most marked advances in understanding the ocean basins have 

 come about through geological and geophysical investigations of the sea 

 floor o Less than fifteen years ago, little was known about the ocean 

 bottom and its structure , There were few reliable soundings,, no seismic 

 refraction results, and very little magnetic or gravity data„ Geothermal 

 measurements were unknown,, Within the past decade precision depth 

 recorders and seismic refraction techniques have evolved, gravity meters 

 have been developed that can operate on surface ships, highly sensitive 

 magnetometers have been towed routinely by research ships and geothermal 

 measurements have been carried out over large areas of the ocean, A 

 large part of the significant advances in this field can be attributed 

 to the massive effort that has been undertaken, but, in addition, some 

 of the success can be traced to the fact that once a marine geophysical 

 technique has been developed, it has almost invariably proved simpler 

 and quicker to collect data at sea rather than on the continents „ 



Results of geological and geophysical research at sea during the past 

 decade may be divided into three categories „ The first is the identi- 

 fication and charting of the massive features that characterize the 

 ocean bottom - the trenches, mountain ranges and sea mounts , Even today 

 these features are known only in the most gross detail „ Secondly, 

 the nature and composition of the vast blanket of sediments have been 

 investigated and described - again only in a cursory manner. Third, 

 and more recently, the structure of the crust beneath the sediments has 

 been examined, and attempts are being made to determine the orogenic 

 processes that are continually modifying it. Results from- all three 

 of these categories are providing the fundamental knowledge required 

 to understand basic problems such as the origin of the earth and other 

 planets, 



DEPARTMENT OF DEFENSE 



DEPARTMENT OF THE NAVY 



Office of Naval Research FY-62 $6,160,000 



FI-63 $7,380,000 

 The geological and geophysical research program of the Office of Naval 

 Research has, for the most part, been directed at a fundamental compre- 

 hension of the sea floor, its substructure and history. 



One of the prime objectives in the program is to describe the sea floor, 

 delineating the major features such as trenches, ridges and sea mounts 

 and to understand their origin. This effort is carried out by all sea- 

 going vessels supported by ONR, Precision depth recorders will be 



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