2 4 



THE FLOOR OF THE OCEAN 



FIGURE 10. MAP OF THE SEYCHELLES PLATEAU. DEPTHS IN METERS. 



hidden sub-oceanic crust, let us next consider the other geophys- 

 ical line of investigation. Here too we are to deal with facts 

 which for the most part were unknown before the beginning 

 of the present century. Their discovery has been made by ex- 

 perts in geodesy, a science originating among the ancient 

 Greeks, but until recently not developed far enough for the 

 needs of our problem. 7 



The chief aim of the geodesist is to determine the true figure 

 or shape of the earth and thus make possible an accurate map- 

 ping of lands and seas. By "figure of the earth" is meant either 

 of two things. On the one hand, the phrase signifies the shape 



