60 THE POORNESS OF OUR [Chap. X. 



deposits; and that not a cave or true lacustrine bed is 

 known belonging to the age of our secondary or palaeo- 

 zoic formations. 



But the imperfection in the geological record largely 

 results from another and more important cause than 

 any of the foregoing; namely, from the several forma- 

 tions being separated from each other by wide intervals 

 of time. This doctrine has been emphatically admitted 

 by many geologists and paleontologists, who, like E. 

 Forbes, entirely disbeheve in the change of species. 

 ■When we see the formations tabulated in written works, 

 or when we follow them in nature, it is difficult to 

 avoid believing that they are closely consecutive. But 

 we know, for instance, from Sir E. Murchison's great 

 work on Eussia, what wide gaps there are in that coun- 

 try between the superimposed formations; so it is in 

 North America, and in many other parts of the world. 

 The most skilful geologist, if his attention had been 

 confined exclusively to these large territories, would 

 never have suspected that, during the periods which 

 were blank and barren in his own country, great piles 

 of sediment, charged with new and peculiar forms of 

 life, had elsewhere been accumulated. And if, in each 

 separate territory, hardly any idea can be formed of the 

 length of time which has elapsed between the consecu- 

 tive formations, we may infer that this could nowhere 

 be ascertained. The frequent and great changes in 

 the mineralogical composition of consecutive forma- 

 tions, generally implying great changes in the geography 

 of the surrounding lands, whence the sediment was 

 derived, accord with the belief of vast intervals of time 

 having elapsed between each formation. 



We can, I think, see why the geological formations 



