156 THE PERMANENCE OF OCEANS. [CH. Ill 



There are, it is true, those who would evolve a continent 

 to account for the range of a genus of beetles ; but on the 

 whole the evidence is against any such radical views of 

 past changes in the positions of oceans and continents. 

 The superstition of Atlantis connecting Africa and America 

 has perhaps not quite died away; and Mr H. 0. Forbes 

 would relegate the tropical island of Madagascar, not to 

 mention the colder and more southern regions, to the icy 

 clasp of the Antarctic continent. 



Evidence in favour of Permanence of Oceans. 



The evidence in favour of the permanence of oceanic 

 area as such has been recently summed up by Mr Blan- 

 ford 1 . The arguments are fourfold. 



I. It has been ascertained that the density of the 

 earth's crust below the deep oceans is greater than that 

 elsewhere. This leads to the inference that this has been 

 so always, because denudation, if the ocean bottom had 

 been ever dry land, would have removed this inequality. 

 The detritus washed away by the action of rivers, rain, 

 and such causes would have tended to equalise the density 

 of the land everywhere. Mr Blanford however points 

 out in criticism of this suggestion that the observations, 

 due to Archdeacon Pratt, were made only in the Indian 

 Ocean, and may perhaps not hold universally. The 

 argument therefore is not of that weight which may be 

 fairly attached to some other considerations. 



1 Presidential Address to Geological Society, 1890. 



