TERTIARY. 127 



CHAPTER VI. 



TERTIARY. 



Najne and lithological characters . — Arrangement of the beds. — Fossils. — Era of the 

 deposit. — Thickness. — (Sec 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 tlie 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 diff"erences. 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 arc 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 witli 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 da^vn 

 of the present. To separate, therefore, the last term of the threefold division, will rather mar 

 the beauty and break the order whicli is established, without bringing with it any advantage 

 to the same. 



