540 THE UNIVERSE. 



future. And thus every generation that appears is only 

 the corollary of that which is expiring, and the prelude of 

 that which is about to spring into life. The stages of crea- 

 tion, except some rare oscillations, follow a rising scale. 

 Nature seems to proceed by a succession of essays before 

 fashioning her more splendid chefs-d'oeuvre ; sundry minute 

 crustaceans, a few molluscs, precede the reptiles, and these 

 prelude the creation of birds and mammals ! 



The earth is only an immense cemetery, where each gen- 

 eration acquires life at the expense of the debris of that 

 which has just expired ; the particles of our corpses form 

 new materials for the beings which will follow us. But we 

 have now reached an epoch of transition ; the exhausted 

 creative powers are experiencing almost a period of arrest ; 

 they are waiting till new telluric perturbations awaken 

 them from their torpor ! 



The first compact crust which enveloped the globe was 

 only formed by the cooling down and solidification of its 

 superficial, once incandescent, layers. Hence the beds 

 which compose it are called primitive or plutonic, in order 

 to indicate their antiquity or igneous origin. 



The strata which overlie the primitive rocks owe, on the 

 contrary, their formation to deposit from the waters ; and 

 for this reason are called alluvial or neptunian strata. 

 These are divided into four leading groups : the transition 

 rocks, secondary rocks, tertiary rocks, and diluvium. 



