67 
I would not by any means deny the agency of animal or 
vegetable life in promoting the formation of these rocks, for 
knowing what we do of the separation of carbonate of lime 
from our own seas by the little coral polype, and of the 
decomposition of carbonic acid when held in solution by 
plants and the lowest grades of animal life, it would be very 
unphilosophical so to do. And the very fact of the sea having 
teemed with animal and vegetable life in the form of encre- 
nites, sponges, &c, at the time of the deposition of the 
mountain limestone, is a proof that they must have exerted 
some important influence on its formation. The decom- 
position of the carbonic acid was, consequently, another 
cause of the crystallization of the carbonate of lime, and a 
means of supplying an equivalent quantity of pure oxygen 
gas to the atmosphere, and hence preparing it for a higher 
grade of animal existence. 
An annual destruction of a large number of this low grade 
of organized beings would necessarily take place, and their 
remains would be embedded in the crystalline mass. These 
remains would be subjected to the putrefactive process of 
decomposition, in consequence of the exclusion of atmos- 
pheric air ; and this process has produced such an important 
alteration in the composition and appearance of these rocks, 
that were we not to take it into consideration, we should come 
to very wrong conclusions regarding their formation. It is 
well known that these rocks contain protoxide of iron, and 
some metallic sulphurets. Now as such compounds cannot be 
formed in the presence of oxygen, and as no animal can exist 
without an abundant supply of this element, it is clear that 
animal life could not be sustained in waters which deposited 
them. These metallic compounds could not, consequently, 
have been originally deposited as sulphurets or protoxides, 
but in some higher stage of oxidation. Now the process of 
putrefaction is well known to be a deoxidizing process, and 
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