GEOLOGY. 579 



of the family of our Coniferee, their boughs laden with 

 fruit. ■ ., . 



These vast primeval forests, which the course of ages 

 was to annihilate, sprang up on a heated and marshy soil, 

 which surrounded the lofty trees with thick compact masses 

 of herbaceous aquatic plants, intended to play a great 

 l^art in the formation of coal. 



The luxuriant vegetation of the coal period was cer- 

 tainly favoured by the enormous heat which the scarcely- 

 chilled terrestrial crust still preserved, as also by the 

 dampness of the atmosphere, and very probably by the 

 great abundance of carbonic acid Avhich it then contained. ^ 



Although a thick and magnificent mantle of foliage 

 covered the globe, everything wore a strange, gloomy aspect. 

 Everywhere rose gigantic Equiseta and ferns, drawing up 

 an exu^berance of life from the fertile and virgin soil. The 

 latter in their aspect resembled palms, and at the least 

 breath of wind waved their crowns of finely-cut leaves like 

 flexible plumes of feathers. A sky, ever sombre and veiled, 

 oppressed Avitli heavy clouds the domes of these forests: 

 a wan and duljious light scarcely made visible the dark 

 and naked trunks, shedding on all sides a shadowy and 

 indescribable hue of horror. This rich covering of vege- 

 tation, which extended from pole to pole, was sad and 

 utterly silent, as well as strangely monotonous. Not a 



1 At the preseut time the atmosphere only contains a thousandth part of car- 

 bonic acid, whereas, according to Mons. A. Brongniart, there were at the car- 

 boniferous period seven to eight parts in a luindred. This acid being an indis- 

 pensable part of the food of plants, to which it gives up all its carbon, its 

 presence easily explains the great development of the antediluvian forests of this 

 period, and as such a quantity of acid in the air would clearly have been fatal to 

 animals of a higher degree of development, such as mammals and birds, so none 

 are met with at that time. Reptiles and mammals only appeared when the 

 plants and trees, by their absorption of the carbonic acid as food, had necessarily 

 purified the atmosphere sufficiently to allow of animal life going on freely. 



