as indicated in the results of Geognosy . 121 
oldest transition rocks containing petrifactions, we witness very 
remarkable gradations of character. The newest formed strata 
are loose in their texture, and usually horizontal in their posi- 
tion. In proportion as we retire from these, towards the older 
formations, the texture becomes more compact and crystalline, 
and the- strata become more inclined and distorted. These cha- 
racters may be traced, by comparing the common loose marl of 
a peat-bog with the firmer chalk ; the compact floetz limestone 
with the transition marble ; or the peat itself with the older beds 
of wood-coal, or the still older beds of coal of the independent 
coal formation. The organic remains in the newer strata are yet 
unaltered in their texture, and easily separable from the matter 
in which they are imbedded. In the older rocks, the remains 
are changed into stone, and intimately incorporated with the sur- 
rounding rocks. These facts are of vast importance, in a geolo- 
gical point of view, as they make us acquainted with the origi- 
nal condition of the matter with which the organic remains were 
enveloped, and lead us to believe that the bed now in the form 
of limestone or marble, was once loose as chalk, or even marl ; 
that coal once resembled peat ; and that the strata of sandstone 
and quartz rock were once layers of sand. They are no less 
interesting when viewed in connection with the characters pre- 
sented by the petrifactions of the different aeras. 
The fossil remains of the alluvial strata, nearly resemble the 
same parts of the animals which live on the earth at present ; 
and, in the newer strata, the remains of existing races are found. 
As we trace, however, the characters of the petrifactions of the 
floetz and transition rocks, we find the forms which they exhibit, 
differing more and more from the animals of the present day, in 
proportion as the rocks in which they are contained exhibit new 
characters of texture, position, and relation. 
It is impossible to regard these concomitant circumstances as 
accidental. Their co-existence indicates the relation, and leads 
to the conclusion, that the revolutions which have taken place in 
the animal kingdom have been produced by the changes which 
accompanied the successive depositions of the strata. Accord- 
ing to this view of the matter, the animals and vegetables with 
which the earth is peopled at present, could not have lived at 
the period when the transition rocks were forming. A variety 
