THE AGE OF THE EAETH. 19 



entitled, ''The Doctrine of Uniformity in Geology briefly 

 refuted." 



"The 'Doctrine of Uniformity' in Geology, as held by many of the 

 most eminent of British Geologists, assumes that the earth's surface and 

 upper crust have been nearly as they are at ]>resent in temperature, and 

 other physical qualities, during millions of millions of yeai's. But the heat 

 ivhich we kaou; hji observation^ to be noro conducted out of the earth yearly 

 is so great, that if this action had been going on with any approach to 

 uniformity for 20,000 million years, the amount of heat lost out of the 

 earth would have been about as much as would heat, by 100° Cent., a 

 quantity of ordinary surface rock of 100 times the earth's bulk. This 

 would be more than enough to melt a mass of surface rock equal in bulk 

 to the whole earth. No hypothesis as to chemical action, internal fluidity, 

 effects of pi'essure at great dej^th, or possible character of substances in 

 the interior of the earth, possessing the smallest vestige of probability, 

 can justify the supposition that the earth's upper crust has remained 

 nearly as it is, while from the whole, or from any part, of the earth, so 

 great a quaiitity of heat has been lost." 



§ 14. The sixteen words which I have emphasized in read- 

 ing this statement to yon (italics in the reprint) indicate the 

 matter-of-fact foundation for the conclusion asserted. This 

 conclusion suffices to sweep aAvay the whole system of geolo- 

 gical and biological speculation demanding an "'inconceiv- 

 ably" great vista of past time, or even a few thousand million 

 years, for the history of life on the earth, and approximate 

 uniformity of plutonic action tln-oughout that time ; ^vhich, 

 as Ave have seen, was very generally prevalent thirty years 

 ago among British Geologists and Biologists ; and which, I 

 must say, some cf our chiefs of the present day have not yet 

 abajidoned. Witness the Presidents of the Geological and 

 Zoological Sections of the British Association at its meetings 

 of 1893 (Nottingham), and of 1896 (Liverpool). 



Mr. Teall : Presidential Address to the Geological Section, 1892, 

 "The good old British shiji ' Uniformity/ built by Hutton and refitted 

 by Lyell, has won so many glorious victories in the past, and appears still 

 to be in such excellent fighting trim, that I see no reason why she should 

 haul down her colours either to ' Catastrophe ' or ' Evolution.' Instead, 

 therefore, of acceding to the request to ' hurry up ' we make a demand 

 for more time." 



Professor Poulton : Presidential Address to the Zoological Section, 1896. 

 " Our argument does not deal with the time required for the origin of 

 life, or for the development of the lowest beings with which we are 

 acquainted from the first formed beings, of which we know nothing. 

 Both these processes may have I'ecpiired an immensity of time ; but as we 

 know nothing whatever about them and have as yet no prospect of 

 acquiring any information, Ave are compelled to confine ourselves to as 

 niuch of the process of evolution as we can infer from the structure of 

 livino- and fossil forms — that is, as regards animals, to the development of 

 the simplest into the most complex Protozoa, the evolution of the 



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