GEOLOGY. 585 



pact, herbaceous vegetation enveloping the great plants of 

 the coal-forests which played the principal part in the 

 production of coal, and that by its ceaseless renewal and 

 change the coal was produced by a transformation analo- 

 gous to that which our aquatic plants undergo when trans- 

 formed into turf. This theory offers a better explanation of 

 the abundance and thickness of the coal-seams. We do not 

 exactly make out the nature of the chemical phenomena 

 Avliich must have taken place during such a fundamental 

 metamorphosis ; but what is clear is, that this Avas princi- 

 pally effected under the influence of the immense pressure 

 and great heat which the plants experienced during the 

 time they were submerged under water, owing to the sub- 

 sidence of the soil on which they had lived and died. 



CHAPTEE IV. 



SECONDARY EPOCH. 



In this epoch everything strongly contrasted with that 

 which preceded it. In the latter the vegetable kingdom 

 predominated during its Avhole course to an extraordinary 

 extent; in this the animal kingdom seems to liaA^e al^sorbed 

 all the vital forces of the glol^e. 



The secondary strata Avere peopled l;)y a fauna altogether 

 ncAV, and more and more exuberant. The reptiles astonish 

 us by their niunber, their gigantic size, and their uuAvontcd 

 forms; antique and incomprehensible inhabitants of the 

 globe, reproduced in all their parts to our Avondering eyes 

 by the genius of a Cuvier and an Oavcu! It is to this 



