3(14 M. Broiignian on the Vegetaiwn of 



and other sedimentary rocks, but seems to me incompatible 

 with many circumstances which the coal depositcs present. 



It may be objected to the first hypothesis, which appears to 

 us the most probable, that we now no longer see peat forma- 

 tions entirely, or almost entirely, composed of Ferns and similar 

 plants ; but the circumstances under whose influence these ve- 

 getables grew were very different from those which now exist, 

 and it is probable that many of these circumstances were calcu- 

 lated to facilitate the formation of such peat formations, lie- 

 sides, it is perfectly well known that many plants of these families 

 grow abundantly in localities of this kind ; the Equiseta, for ex- 

 ample, Osmunda regalis, several Aspidia and Lycopodia, grow 

 habitually in our peat soils. Lastly, we have scarcely a doubt 

 that, at this remote epoch, our atmosphere had a very different 

 composition from what it has now, and that this difference exert- 

 ed a powerful influence upon the formation of those beds of ve- 

 getable combustible. We shall revert to this subject. 



Let us now take a review of what we have just said respecting 

 the nature of the vegetation of our globe at this epoch, and the 

 data which it supplies, with reference to its physical constitution. 

 We see that the vegetable kingdom, composed almost entirely of 

 gigantic vascular cryptogamic plants^ indicates the existence, at 

 this epoch, of a temperature much higher than that of our cli- 

 mates, and perhaps superior to that of the warmest regions of the 

 earth ; that this same vegetable nature seems to prove, that our 

 globe was almost entirely covered by the sea, from the bosom of 

 which there rose some islands, whose vegetables, after their death, 

 formed beds of a kind of peat, which afterwards slipping into the 

 sea, as Deluc imagined, or covered by circumstances which it 

 does not form part of our object to examine, by beds of rocks of 

 various kinds, gave rise to the coal deposits. . ->ijjo(i -> 



We have not nearly so many data with respect to the vegeta- 

 tion of the subsequent periods. Thus, the remains of vegetables 

 discovered in the variegated sandstone are too few in number, to 

 allow us to draw any inference from them, as to the state of the 

 globe at that epoch. We can only infer, from the presence of an 

 arborescent fern in this formation, that the temperature was at 

 that period still much higher than that of our climates, and was 

 probably similar to that of the intertropical regions. 



