66 THE ORIGIN OF fiPECIES 



But the imperfection in the geological record largely 

 results from another and more importunt cause than any 

 of tlie foregoing; namely, from the several formations 

 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 disbelieve 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 believ- 

 ing that they are closely consecutive. But we know, for 

 instance, from Sir R. Murchison's great work on Eussia, 

 what wide gaps there are in that country 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 accu- 

 mulated. And if, in each separate territory, hardly any 

 idea can be formed of the length of time which has 

 elapsed between the consecutive formations, we may infer 

 that this could nowhere be ascertained. The frequent 

 and great changes in the mineralogical composition of 

 consecutive formations, 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 

 of each region are almost invariably intermittent; that is, 

 have not followed each other in close sequence. Scarcely 

 any fact struck me more when examining many hundred 



