584 THE UNIVERSE. 



at that time mixed with the atmosphere, wliich, though 

 particularly favourable to the life of plants, must have 

 been fatal to all animals endowed with active respiration. 

 But though the atmosphere Avas poisonous, the seas, on 

 the contrary, uniting together all conditions most favour- 

 ble to life, Avere peo2:)led Avith shelled molluscs and fish. 



After haA'ing lent life to the primitive ages of the giol^e, 

 these strange forests completely disappeared in the lapse 

 of ages, and they have noAv become almost impossiljle to 

 recognize, OAAdng to the transformations they have under- 

 gone in nature's immense subterranean store-houses. 



There can, hoAvever, be no doubt about the matter. 

 It is clearly the debris of these antique forests of our 

 gradually cooled-doAvn planet that constitutes the coal of 

 the present time. Science, carrying its torch even into 

 the dark regions from AAdience this debris proceeded, has 

 discovered all its constituent parts. Amid the black and 

 gleaming masses of the coal strata abundant impressions 

 have Ijcen found of the plants Avhich produced the antedi- 

 luvian combustilile, and from these primitive medals of 

 creation we have seen science Aveave the history of the 

 daAvn of teiTCstrial vegetation. 



But by Avliat mysterious phenomena Avas this extra- 

 ordinary transf<:)rmation effected? At first it Avas thought 

 that the forests of the coal era had been overthroAAm or 

 borne away by the violence of currents, and that their 

 trunks, locked together, after having floated about like 

 immense rafts, had collected in creeks, and there become 

 changed into layers of coal. 



But this theory, though seductive from its simplicity, is 

 inadniissiljle, because the trunks, in spite of their bulk, 

 Avould yield only a very thin layer of coal. M. Elie de 

 Beaumont, on the other hand, thinks that it Avas the com- 



