34 



INTERNATIONAL ASPECTS OF OCEANOGRAPHY 



East Indian Archipelago on a scale of 1:2,500,000. 

 Plate 2 is a colored bathymetric chart of the East 

 Indian Archipelago on a scale of 1 : 5,000,000. It is 

 also gratifying to record that the International 

 Hydrographic Bureau is publi-shing a revised edition 

 of the Carte bathym^trique gen^rale des Oceans. 



The foregoing few notes on recent progress in the 

 study of sea-bottom configuration are gratifjdng, 

 but there are still two enormous areas of sea bottom 

 on which only a little information is available. 

 These are most of the Pacific Ocean, except near its 

 shores, between the Equator and 50°S. latitude, 

 and, except adjacent to Antarctica, most of the 

 Indian Ocean east of longitude 70°E. and south of 

 latitude 10°S. There are other areas on which 

 information is inadequate, such as that between 

 the Hawaiian Islands and the American coast, but 

 the two above indicated are the most outstanding 

 large areas on which there is little or no inform- 

 ation. 



The remarks so far made apply to the larger fea- 

 tures of bottom configuration, but before leaving the 

 subject some consideration should be given to the 

 more minute features of relief. It would require 

 considerable searching of literature to discover who 



was the first to recognize that there are on the ocean 

 floor earth-forms that are trench-like, others that are 

 precipitous and simulate fault-scarps, et cetera, but 

 we do know that the invention of radio-acoustic 

 position-finding and the invention of echo-sounding 

 devices has made possible the recognition of minutiae 

 of sea-bottom configuration that was entirely im- 

 possible only a few years ago. While in sight of 

 land, by making closely spaced line-soundings it is 

 possible to develop the side walls and floor of a 

 trench, as Shepard has done,' but when farther out 

 at sea other methods of successive place-finding are 

 essential. It has now been convincingly shown that 

 the continental shelf off the east coast of the United 

 States is incised by numerous trenches which can be 

 traced to depths of 1,800 meters or more.'' The 

 origin of these features is one of the great enigmas 

 of geology and oceanography. They are mentioned 

 here in the hope that research on them may be 

 extended to other parts of the world. 



' Shepard, F. P., Continued exploration of California 

 submarine canyons: Amer. Geophys. Union, meeting 1936, 

 Trans, pp. 221-223, 1936. 



* Smith, Paul A., Submarine valleys: U. S. Coast and 

 Geodetic Surv. Field Engineers Bull. No. 10, pp. 150-158, 

 Dec. 1936. 



