342 ORIGIN OF SPECIES 



not a cave or true lacustrine bed is known belonging to the 

 age of our secondary or palaeozoic formations. 

 y^ But the imperfection in the geological record largely re- 

 sults from another and more important cause than any of the 

 foregoing; namely, from the several formations being sep- 

 arated from each other by wide intervals of time. This doc- 

 trine has been emphatically admitted by many geologists and 

 palaeontologists, 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 believing that they are closely consecutive. 

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

 work on Russia, 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 pe- 

 culiar 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 mineral- 

 ogical composition of consecutive formations, generally im- 

 plying 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. 

 C' We can, I think, see why the geological formations of each 

 \ region are almost invariably intermittent; that is, have not 

 1 followed each other in close sequence. Scarcely any fact 

 struck me more when examining many hundred miles of the 

 South American coasts, which have been upraised several 

 hundred feet within the recent period, than the absence of 

 any recent deposits sufficiently extensive to last for even a 

 short geological period. Along the whole west coast, which 

 is inhabited by a peculiar marine fauna, tertiary beds are so 

 poorly developed, that no record of several successive and 

 peculiar marine faunas will probably be preserved to a distant 



