36 A. BLTTT. [NO. 12. 



If we were to attempt to establish geological formations 

 with the aid afforded by remains of land animals and land plants, 

 the borders of these would not coincide with the borders estab- 

 lished by an investigation of the marine fauna. 1 To name an 

 instance, the appearance of dicotyledons does not coincide with 

 any formation's limit, but they appear first in the upper Cretaceous 

 formation in a multitude of forms. 



We know from the Tertiary period, when we disregard the 

 layers of the great mountain ranges, only formations from the 

 shallow seas. The Tertiary layers that correspond to the deeper 

 seaformations of the older periods, and which, without their 

 formation being interrupted by the numerous slight oscillations 

 of the beach lines, were deposited farther from land in those 

 periods, still, for the greater part lie concealed from our vision 

 in the depths of the seas. 



Terrestrial formations, fresh-water and coast formations, such 

 as we find in abundance in our Tertiary basins, are specially 

 exposed to destroying influences ; because they are more frequently 

 upheaved over the protecting waters. In the ancient cycles such 

 formations are more rare, probably, in a great measure, for the 

 reason that they have been destroyed by denudation. We must 

 therefore conclude that the formations of the Tertiary period 

 would resemble those of the ancient cycles far more, if our 

 knowledge of them was equally great. From the ancient cycles 

 we frequently recognize, especially, deeper sea formations, whilst 

 from the younger cycles we recognize formations, principally, 

 from the shallow seas or fresh-water. In a distant future the 

 Tertiary formations, then remaining visible, will come to resemble 

 those now left visible from the more ancient cycles. 



