Here is irrefutable evidence of what geologists call a transcurrent 

 fault, with a displacement an appreciable fraction of the size of the 

 oceans themselves! What are the giant forces capable of bringing 

 about such large-scale movement in the crust underlying the sea 

 floor? And what happens to the displacement if it bites into a 

 continental margin? Quite simply, we do not know; there is no 

 evidence of faulting on such a grand scale along the American coast 

 itself. 



If we have faith in our data, and in our present interpretation of 

 them, we must admit the possibility that enormous blocks of the 

 Earth's crust can be moved around on a scale envisioned by those 

 who favor the theories of continental drift. Further evidence — the 

 ancient positions of the Earth's magnetic poles, deduced from the 

 fossil magnetic properties of rocks — also leads us to believe that 

 the continents themselves have been able to float about in the mantle 

 rock. And we must include the mid- Atlantic Ridge in any discus- 

 sions of continental drift, as well as many of the smaller features, 

 such as the median valley on the ridge and the non-magnetic sea- 

 mounts ofl" the continental margins. 



The deep-sea floor is still defying our attemps to pry out its 

 secrets. Only slowly and with painstaking care can we fit together 

 the thousands of pieces of the jigsaw puzzle and see the whole 

 picture. In time, deep-diving submarines and bathyscaphes will 

 permit us to wander about at will through the ocean depths and 

 peer through the foggy gloom; deep holes through the oceanic 

 crust will test our conclusions about the deep structure. We will be 

 able to fill in the details, now unknown, and delve further into the 

 problems of the sea floor. Inevitably, the more we find out, the 

 more questions and puzzles will arise. Yet in this field we are on 

 the brink of discoveries and explorations quite as exciting and just 

 as rewarding as man's first steps into space. 



The illustrations along ttie bottom of 

 these pages sIjow techniques, past and 

 present, to gain information about the sea 

 floor: a dredging device used by Count Luigi 

 Marsigli, who maintained that the deep ocean 

 was not a "bottomless abyss"; William Beebe's 

 bathysphere which Is lowered from a ship and 

 takes its occupant to the ocean bottom; 

 A. S. Laughton's automatic camera which 

 takes pnotographs of the sea bed; and 

 Auguste PIccard's bathyscaphe, capable 

 of taking men to the deepest regions 

 of the oceans. Its occupants ride In the 

 small sphere attached to the gasoline-filled 

 float. Because gasoline is lighter than 

 water, the bathyscaphe rises to the surface 

 when ballast Is dropped. 



