308 
IMPERFECTION OF THE 
Chap. IX. 
To the question why we do not find records of these 
vast primordial periods, I can give no satisfactory 
answer. Several of the most eminent geologists, with 
Sir E. Murchison at their head, are convinced that 
we see in the organic remains of the lowest Silurian 
stratum the dawn of life on this planet. Other highly 
competent judges, as Lyell and the late E. Forbes, 
dispute this conclusion. We should not forget that 
only a small portion of the world is known with ac¬ 
curacy. M. Barrande has lately added another and 
lower stage to the Silurian system, abounding with 
new and peculiar species. Traces of life have been 
detected in the Longmynd beds, beneath Barrande’s 
so-called primordial zone. The presence of phosphatic 
nodules and bituminous matter in some of the lowest 
azoic rocks, probably indicates the former existence of 
life at these periods. But the difficulty of understand¬ 
ing the absence of vast piles of fossiliferous strata, 
which on my theory no doubt were somewhere accu¬ 
mulated before the Silurian epoch, is very great. If 
tliese most ancient beds had been wholly worn away 
by denudation, or obliterated by metamorphic action, 
we ought to find only small remnants of the formations 
next succeeding them in age, and these ought to be 
very generally in a metamorphosed condition. But the 
descriptions which we now possess of the Silurian de¬ 
posits over immense territories in Eussia and in North 
America, do not support the view, that the older a for¬ 
mation is, the more it has always suffered the extre¬ 
mity of denudation and metamorphism. 
The case at present must remain inexplicable; and 
may be truly urged as a valid argument against the 
views here entertained. To show that it may hereafter 
receive some explanation, I will give the following hy¬ 
pothesis. From the nature of the organic remains which 
