384 
impressed with the sense of the earth's immense antiquity. 
Upwards of thirty formations, or eras of creation, containing 
thick beds of fossil remains, have already been discovered, and 
without doubt many more remain to be explored. These must 
have taken very protracted periods for then* accumulation % 
beds of sand and gravel may be deposited in a single season, 
but thick masses of organic remains must have required a 
lengthened time for the production, the growth, and the life 
of the vegetable or animal forms of which they were once a 
part. The duration of the different geological formations is 
not to be reckoned by centuries, but by millenniums. When 
we are told, for instance, that in Nova Scotia there are found 
“ fifty or even a hundred ancient forests, buried one above the 
other, with the roots of trees remaining in their original 
position," we conclude that as each of these forests must 
have required at least five hundred years for the formation of 
the soil in which it grew, for the growth and decay of the 
trees, in so far as we can judge, the epoch to which they be- 
long must have extended from forty to fifty thousand years. 
Masses of shells and corals, “ hundreds of feet in thickness, 
demand an equally lengthened period for their deposition. 
Another formation, of less extent than these, conveys, per- 
haps, even more vividly than they do, the idea of great dura- 
tion. Sir C. Lyell, in describing some lacustrine strata that 
are found in Auvergne, gives the following statement : The 
entire thickness of these marls is unknown ; but it certainly 
exceeds, in some places, seven hundred feet. They are thinly 
foliated, a character which frequently arises from the innu- 
merable thin plates, or scales, of that small animal called 
cyvris, a genus which comprises several species, of which some 
are recent, and may be seen swimming swiftly through the 
waters of our stagnant pools and ditches. The animal resides 
within two small valves, not unlike those of a bivalve shell, and 
moults its integuments annually, which the conchiferous mol- 
luscs do not. This circumstance may partly explain the 
countless myriads of the shells of the cypris which were shed 
in the ancient lakes of Auvergne, so as to give rise to divi- 
sions in the marl as thin as paper, and that, too, in masses 
several hundred feet thick." The little shells or scales, here 
referred to, are smaller in diameter than the head of the 
smallest pin ; they are annually shed, and float lightly in the 
stream. Here, we are told, that layers of them divide the 
marl into beds as thin as paper. These facts naturally lead 
to the conclusion that, year by year, as the moulting season 
came round, and these diminutive denizens of the stream and 
pool dropped their scales, their cast-off habiliments were car- 
