136 



UPHEAVAL AND SUBSIDENCE 



[Ch. VII. 



sedimentary 



not only of past ages, but of one 



geological epoch, or even the fraction of an epoch, has ex- 

 ceeded immeasurably all the fluctuations of the inorganic world 



But we have still to 



man 



time 



paragraph of the earth's autobiography relates, was not 

 equally immense when contrasted with a brief era of 3,000 or 

 5,000 years. The real point on which the whole controversy 

 turns, is the relative amount of work done by mechanical 



past and present. Before 



time 



mine 



we must have some fixed standard by which to measure the 

 time expended in its development at two distinct periods. It 

 is not the magnitude of the effects, however gigantic their 



inform us in the 



proportions, which 



whether the operation was sudden or gradual, insensible or 



slightest degree 



paroxysmal. 



must 



hat a slow process could 



never in any series of ages give rise to the same results. 



The advocate of paroxysmal energy might assume an uni- 

 form and fixed rate of variation in times past and present 

 for the animate world, that is to say, for the dying-out and 

 coming-in of species, and then endeavour to prove that the 

 changes of the inanimate world have not gone on in a cor- 

 responding ratio. But the adoption of such a standard of 

 comparison would lead, I suspect, to a theory by no means 

 favourable to the pristine intensity of natural causes. That 

 the present state of the organic world is not stationary, can 

 be fairly inferred from the fact, that some species are known 

 to have become extinct in the course even of the last three 

 centuries, and that the exterminating causes always in acti- 

 vity, both on the land and in the waters, are very numerous ; 

 also, because man himself is an extremely modern creation ; 

 and we may therefore reasonably suppose that some of the 

 mammalia now contemporary with man, as well as a variety 

 of species of inferior classes, may have been recently intro- 

 duced into the earth, to supply the places of plants and ani- 

 mals which have from time to time disappeared. But granting 



that some such secular variation in the — 



botanical worlds is going on, and is by no means wholly in- 



zoological 



and 



£ 





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