TERTIARY. 
127 
CHAPTER VI. 
TERTIARY. 
Name and lithological characters. — Arrangement of the beds. — Fossils. — Era of the 
deposit .— Thickness. — (See Plates I. II.) 
The valley of Lake Champlain, and the basin of the River St. Lawrence, supports a forma¬ 
tion composed of clay and sand, to which the name tertiary has been applied. 
In employing simply the word Tertiary, in the place of Post- Tertiary, the designation which 
of late has been given to it, I am influenced by the conviction that no advantage can be de¬ 
rived by multiplying names where ' real differences do not exist, or where they are doubtful, 
or resolve themselves into mere shades of differences. Looking at the Tertiary of modern 
authors, as it is, and regarding it as a distinct formation from the Secondary, I can see no 
advantage in making a farther division of what must be admitted to be geologically a recent 
deposit, and the several divisions of which must belong to the.modern era. The terms 
Eocene, Meiocene and Pleiocene, express fully all the subdivisions which can profitably be 
made in a formation where lines of demarkation do not really exist, and where they are liable 
to vary annually, and with the progress of discovery, and especially when there is really no 
fixed standard of comparison. 
Who can suppose, on reflection, that percentage, is a universal law ; or that it can be esta¬ 
blished, except loosely, and subject to vary with the progress of discovery ? It is true, that 
where there are gradations, we may make three terms, one of which will be a mean. But 
all our observations in geology go to prove that neither life, nor the extinction of life, has ever 
been regulated by rigid mathematics; that even the approximation, which may be found to 
prevail in a given region, may be departed from in another. Of the tertiary of Champlain, I 
can consider it only as the expression of the extreme term in the threefold division of the dis¬ 
tinguished author, Charles Lyell, that it is the Pleiocene, or the full developement or dawn 
of the present. To separate, therefore, the last term of the threefold division, will rather mar 
the beauty and break the order which is established, without bringing with it any advantage 
to the same. 
