The Mighty Deep 



side looked upon its own view for the time being 

 as the only right one. But — as again with many 

 difficult problems — the fairer and wider view 

 recognises the possibility of truth in both ex- 

 planations, and probably in the end both will 

 prove to be in a measure right. 



Many other kinds of rock, as well as sand- 

 stone, have been built under ocean-waters in past 

 ages, constructed of minute particles, piled to- 

 gether, and hardened. Some sorts, like sand- 

 stone, are only or chiefly mineral ; while others 

 are only or chiefly *' organic " — that is, are mainly 

 composed of the remains of '' organised " or living 

 beines. About the latter much has to be said in 

 future chapters. 



A very few words in the close of this chapter, 

 as to the classifying of different kinds of Rocks, 

 may not be amiss. 



Ocean-deposits, or Ocean-buildings, are often 

 roughly divided into three groups. 



In " Deep-Sea Deposits" are included all that 

 lie beyond the Hundred-fathom Line, or a depth 

 of six hundred feet. 



In " Shallow- water Deposits" are included all 

 that lie between six hundred feet deep and low- 

 water mark. 



In *' Littoral Deposits " — the word coming from 

 132 



