EAKTH CHANGES AND EVOLUTION 193 



America to be 60,000 square miles. But the area of that con- 

 tinent is about six million square miles, so that deposition goes 

 on about a hundred times as fast as denudation ; while over 

 considerable areas where the deposits are of a sand}^ rather than 

 of a muddy or slaty nature, it may go on a thousand times as 

 fast. This is a most important fact which does not appear 

 to have been taken into full consideration by geologists even 

 to-day. 



The correlative fact as to the ocean bed is, that over the 

 whole of it, when more than the above-named distances from 

 land, what are called " deep-sea oozes " are found. These 

 are formed almost entirely by the calcareous or silicious skele- 

 tons of minute organisms, together with small quantities of 

 decomposed pumice and of meteoric or volcanic dust. Along 

 with these in certain areas the remains of larger marine ani- 

 mals are found, especially the otoliths (or ear bones) of whales 

 and the teeth of sharks. And the extreme slowness of the 

 deposit of these oozes is shown by the fact that it is often im- 

 possible to bring up a dredging from the bottom that does not 

 contain some of these bones or teeth. It seems as if much 

 of the ocean bed were strewn with them ! Now, these oozes, 

 so easily recognised by their component materials and their or- 

 ganic remains, form no part of the upheaved crust of the earth 

 on any of our continents. This is, of itself, a conclusive proof 

 that oceans and continents have never changed places in the 

 whole course of known geological time; for if they had done 

 so (as is still maintained by many rather illogical writers) the 

 epoch of submergence would be indicated by some fragments, 

 at least, of the consolidated ocean ooze which must once have 

 covered the whole continental area.^ 



1 For a full discussion of this question, see my Darwinism, chap, xii.; 

 Island Life, chaps, vi. and x.; and Studies Scientific and Social, vol. i. 

 chap. ii. In this last work the whole argument is summarised and the 

 numerous converging lines of evidence pointed out. 



