14 CHARLES DARWIN 



the first years of the present century that a fixed order 

 of sequence could everywhere be traced among the 

 various superincumbent geological strata. Modern 

 scientific geology takes its rise from the moment of this 

 luminous and luminiferous discovery. With astonishing 

 rapidity the sequence of strata was everywhere noted, 

 and the succession of characteristic fossils mapped out, 

 with the result of showing, however imperfectly at first, 

 that the history of organic life upon the globe had 

 followed a slow and regular course of constant develop- 

 ment. Immediately whole schools of eager workers 

 employed themselves in investigating in separate detail 

 the phenomena of these successive stages of unfolding 

 life. Murchison, fresh from the Peninsular campaign, 

 began to study the dawn of organic history in the gloom 

 of the Silurian and Cambrian epochs. A group of less 

 articulate but not less active workers like Buckland and 

 Mantell performed similar services for the carboniferous, 

 the wealden, and the tertiary deposits. Sedgwick en- 

 deavoured to co-ordinate the whole range of then known 

 facts into a single wide and comprehensive survey. De 

 La Beche, Phillipps, and Agassiz added their share to 

 the great work of reconstruction. Last of all, among 

 those who were contemporary and all but coeval with 

 Charles Darwin himself, Lyell boldly fought out the 

 battle of ' iiniformitarianism,' proving, with all the 

 accumulated weight of his encyclopedic and world- 

 wide knowledge, that every kjiown feature of geological 

 development could be traced to the -agency of causes 

 now in action, and illustrated by means of slow secular 

 changes still actually taking place on earth before our 

 very eyes. 



