Forces and Processes at Work In Ocean Basins 



E. C. BULLARD 



Department of Geodesy and Geophysics, Cambridge University, Cambridge, England 



KNOWLEDGE of the ocean floor has grown in a curious way. In 

 1872 Murray and his colleagues set out in the Challenger on a 

 voyage crossing all the oceans. In the course of this voyage they 

 collected samples of the bottom materials, examined them with 

 such care and wrote so solid a report on them that it remained the 

 main source of knowledge of the ocean floor until the 1930's. In 

 retrospect it is odd how little was done during the sixty years 

 after the Challenger Expedition. The physicists were otherwise 

 engaged, and the oceans were left largely to the biologists. 



In the 1930's there were the first glimmerings of what was to 

 come. By great good fortune Richard Field became interested in 

 the matter and applied his enthusiasm and his unequaled and 

 rather overwhelming powers of persuasion to interest others. Many 

 of those who have contributed to recent developments owe the 

 first impulse directly or indirectly to him. Of course the subject 

 was due for a revival, and there were many other independent 

 new starts: Vening Meinesz's gravity, Revelle's work on the 

 Carnegie samples, Piggot's cores, the U. S. Coast and Geodetic 

 Survey's charts of the canyons off the eastern shores of the United 

 States. In all these ways the subject was awakening again when 

 World War II came, and when it was over the great flood of 

 new knowledge about the ocean floor started to accumulate. 



Some of the things found were expected, or not surprising, such 

 as the shallow oceanic Moho and the thick sediments beneath the 

 continental shelf, but many, perhaps most, were quite unexpected. 

 No one would have predicted turbidity currents, or flat-topped 

 seamounts, or the high oceanic heat flow. Obviously many more 

 surprises are to come, but things have reached a stage when a 



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