318 Ancietit Vegetation of the Earth 



Indeed) at that epoch when hfe first began to be manifested upon 

 our globe, the animals were all confined to the interiour of the 

 waters, and even these presented but diminished specimens of 

 their kinds ,• while a powerful vegetation, forming vast forests, cov- 

 ered, at that early period, all such parts of the earth as were not 

 submerged by the sea ; and each succeeding period of repose has 

 had its own peculiar vegetation, more or less varied, and in greater 

 or less abundance, according to the circumstances which influ- 

 enced the development of the beings that composed it, and per- 

 haps, also, in proportion to the duration of these periods; but 

 almost always entirely diflerent from those of either the preceding 

 or succeeding epochs. 



Of the different associations of vegetables which have succes- 

 sively inhabited our globe, there are none which so pointedly 

 merit our attention as those which seem to have been first devel- 

 oped upon its surface ; which appear, during a long space of time, 

 to have covered with dense forests all those parts of the earth 

 that rose above the general level of the waters, and of which the 

 remains of successive growths, heaped one upon another, have 

 formed our layers of coal, so deep, extensive and numerous ; and 

 in this form the remains of these primeval forests, which have 

 preceded, by so many centuries, the existence of man, and which 

 now supply us Avith fuel, in place of our more modern forests, of 

 which the great increase of the human family is causing a rapidly 

 augmented destruction, have become one of the principal sources 

 of the prosperity of nations. 



None can doubt that coal owes its origin to accumulated masses 

 of vegetables, changed and modified, as probably the layers of 

 peat in our marshes would be, if they had been overlaid by thick 

 coverings of mineral substances, compressed under the weight of 

 these, and subsequently exposed to an elevated temperature. If 

 farther confirmation of this origin were necessary, it is found in 

 the almost ligneous structure which coal sometimes presents, and 

 in the numerous remains of plants contained in the rocks which 

 accompany it.(1) 



(1) The most complete and valuable collection of plates of impressions of these 

 coal plants which is generally accessible, in this country, will be found in this 

 Journal, Vol. xxix, No. 2. This volume contains Dr. Hildreth's valuable paper 

 upon the coal deposites of the valley of the Ohio, which he has accompanied with 

 some thirty pages of excellent drawings of fossil remains and impressions, mostly 

 vegetable, found in the accompanying rocks. — Translator. 



