234 PROGRESS OF SCIENCE IN THE CENTURY. 



types of organic life, which in proportion to their an- 

 tiquity, departed more and more from the aspect of 

 the living world." * 



Along with the achievements of William Smith, 

 we must place the researches of Cuvier and Brongni- 

 art, and of others who early realised the value of 

 fossils as indices in determining the sequence of 

 strata. 



The idea of interpreting the history of the past in 

 terms of changes observed in occurrence in the pres- 

 ent; the conception of the sequence of strata; the 

 recognition of the value of fossils as indices, are three 

 of the foundation-stones of geology which were laid 

 at the beginning of the nineteenth century. 



THE EVOLUTION-IDEA IN GEOLOGY. 



At various dates we find exceptional recognition of 

 the Evolution-Idea as applied to the Earth. It fas- 

 cinated a few long before Darwin brought it home 

 to all. Thus Descartes propounded a scheme of the 

 Earth's development from a globe of molten liquid, 

 and Leibnitz's Protogcea (published long after his 

 death, about the middle of the eighteenth century) 

 contained a similar attempt. Buffon, too, starting 

 with the bold idea that the Earth, like the planets, 

 was detached from the mass of the sun by a cometary 

 shock, sketched with a free hand the successive 

 chapters of a problematical history in his Epochs of 

 Nature (17T8). 



Even when uniformitarianism was in its full 

 strength, inquiring minds here and there were be- 

 ginning to suspect that there was something to be 

 said for the heresies of Buffon, Lamarck, Erasmua 

 * Op. cit., 1892, pp. 9-10. 



