318 Ancient Vegetation of the Earth. 
Indeed, at that epoch when life 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 different 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 
so many centuries, the existence of man, and which 
now supply us with 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. : 
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) 
kaa 
(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 
» Vol. xxix, No.2. This volume contains Dr. Hildreth’s valuable ~ 
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, most!Y 
vegetable, found in the accompanying rocks.— Translator. 
