OF GEOLOGICAL DYNAMICS. 79 



which a record is preserved in stratified deposits. 

 On what calculation is this opinion founded ? 

 One considerable part of the reform in geological 

 speculation for which I ask is, that evidence 

 adduced in favour of the opposite opinion should 

 be thoroughly sifted, and not merely disposed of 

 as matters of opinion, or of faith beyond the realm 

 of reason. 



5. It was, however, in reference to the special 

 subject of my paper, " Geological Time," that I 

 chiefly urged the necessity of reform, and it is 

 satisfactory now to see that in this respect 

 considerable progress must have been made, when, 

 on the 1 9th February, 1869, Professor Huxley 

 ventured before the Geological Society of London 

 to suggest that " the limitation of the period 

 " during which living beings have inhabited this 

 " planet to one, two, or three hundred million 

 " years, may be admitted, without a complete 

 "revolution in geological speculation." When he 

 says that on me rests the onus probandi of my 

 assertion in January, 1868, " that a great reform 

 seemed to have become necessary," as I had 



