Recent Rcscardi Ac(())nj)lishtncnts 



Scripps Institution of Oceanography 



Measuring a manganese concretion brought up from a depth of three miles in the 



Gulf of Alaska. 



GEOLOGY AND GEOPHYSICS OF THE 

 SEA FLOOR 



The use of the recording echo-sounder 

 and other instruments developed during 

 the last decade has made it possible to 

 conduct topographic surveys more rapidly 

 and in greater detail than ever before. 

 Although only a few isolated areas of the 

 deep ocean have been surveyed in adequate 

 detail, characteristic features of the sea 

 floor have been revealed that had not even 

 been suggested by earlier techniques. 



Geophysical methods originally applied 

 to the study of deep geologic strata under 

 the land are yielding information about 

 strata under the ocean. New techniques 

 are also being developed to attack special 

 geophysical problems of the sea floor. Re- 

 sults alreadv obtained are so different in 



fundamental respects from previous theory 

 as to make it obvious that knowledge of 

 the structure and history of the earth must 

 depend largely on the accumulation of a 

 body of data concerning the structure and 

 history of the oceanic areas. 



Recent improvements in coring devices 

 make it possible to penetrate the bottom 

 to depths of more than 100 feet. Sediments 

 of the deep sea far from land have been 

 deposited so slowly and continuously that 

 the analysis of their fossil content and 

 measurements of their radioactivity are re- 

 sulting in a more detailed time-scale for 

 the last million years of geologic history 

 than can be obtained from terrestrial sedi- 

 ments. Oceanic sediments are likewise 

 proving of interest to the astronomers. Cer- 

 tain elements concentrated in the sediments 

 (i.e., nickel), may provide a clue to the 

 historv of the cosmos. 



