234 THE OCEAN 



from such a typical red-clay deposit remote 

 from continental shores are few in number, 

 although they show archaic characters (Dis- 

 cina and other brachiopods, Stephanoscyphus, 

 crinoids, siliceous sponges, etc.). If there be 

 what may be called desert areas on the sea- 

 floor, then they are certainly situated in these 

 red-clay regions. 



Another peculiarity of the red clays is the 

 absence of quartz particles ; indeed, all the 

 truly pelagic deposits far from land contain 

 extremely few traces of quartz- sand except 

 where the ocean is affected by floating ice. 

 This is a very important matter, for in all the 

 terrigenous deposits laid down in deep or 

 shallow water near the continents quartz is 

 the most characteristic constitutent, making 

 up frequently more than half of the deposit. 

 Indeed, the analogues of the now-forming 

 terrigenous deposits are to be found in 

 all geological periods, whereas no analogues 

 can be found of the truly pelagic deposits 

 now being laid down on the floor of 

 the ocean, which cover fully one-half of 

 the surface of the earth. If these terri- 

 genous deposits have been continually pushed 

 up on the continental areas or thrust under 

 them in a more or less viscous or plastic con- 

 dition ever since the first precipitation of rain 

 on the globe, then this would tend to make 



