JSUCCESSIVE STAGES OF DEPOSITION. 113 
vegetables are piled into stupendous monuments 
of the operations of life and death, during ahiiost 
immeasurable periods of past time. *' At the 
sight of a spectacle," says Cuvier, * " so im- 
posing, so terrible as that of the wreck of animal 
life, forming almost the entire soil on which we 
tread, it is difficult to restrain the imagination 
from hazarding some conjectures as to the causes 
by which such great effects have been pro- 
duced." 
The deeper we descend into the strata of the 
Earth, the higher do we ascend into the archaeo- 
logical history of past ages of creation. We 
find successive stages marked by varying forms 
of animal and vegetable life, and these generally 
differ more and more widely from existing 
species, as we go further downw^ards into the 
receptacles of the wreck of more ancient crea- 
tions. 
When we discover a constant and regular 
assemblage of organic Remains, commencing 
with one series of strata, and ending with another, 
which contains a different assemblage, we have 
herein the surest grounds whereon to establish 
those Divisions which are called geological 
formations, and we find many such Divisions 
succeeding one another, when we investigate the 
mineral deposits on the surface of the Earth. 
* Cuvier rapport sur le progres des sciences niiturelles, p. 179. 
GEOL. 1 
