8 THE FLOOR OF THE OCEAN 



The depths stated in column 2 of Table I are averages for 

 all of each basin, including the areas covered by the submerged 

 flanks of the continents. Such shallow floodings of the conti- 

 nental plateaus are exemplified by Bering Sea, Hudson Bay, 

 North Sea, Baltic Sea, China Sea, the extensive shelf areas of 

 the East Indies, and those off the eastern United States, Yuca- 

 tan, Brazil, eastern Patagonia, South Africa, and the British 

 Isles. When these and other regions of shallow water are 

 excluded, we get for the average depths of the open oceans the 

 values of column 3, Table I. 



Clearly the geologist's contact with the sub-oceanic tables of 

 stone which record earth history must be mental rather than 

 physical. Here controlled imagination must be supreme. Be- 

 fore the beginning of the twentieth century there was plenty 

 of imagination, but there were comparatively few facts of ob- 

 servation to control it. Since that time a good start in the 

 establishment of compelling data has been made. The new 

 discoveries have come from study of the submarine morphol- 

 ogy, from sampling of the floor of the ocean, from the geology 

 of islands and continents, and from geophysics. 



Relief of the Sea Bottom 



The floor of the ocean is far from being a monotonous, level 

 plain. Oceanographers are impressed with the variety of top- 

 ographic forms. Thousands of major and minor features have 

 already been charted, and the end is not yet. Here, then, is a 

 long-hidden world, new to science. How to describe it in 

 trenchant, unequivocal words is a problem, analogous to that 

 represented by the map of the Moon. Neither geographer nor 

 selenographer has completed his list of common nouns, names 

 of topographic species; and his list of proper nouns, names of 

 individual reliefs. However, in our oceanic study we shall not 



