282 The Founders of Geology LECT. 



of the reading of every man who would wish to make 

 himself an accomplished geologist. 



Ly ell's work was mainly that of a critic and exponent of 

 the researches of his contemporaries, and of a philosophical 

 writer thereon, with a rare faculty of perceiving the con- 

 nection of scattered facts with each other, and with the 

 general principles of science. As Eamsay once remarked 

 to me, " We collect the data, and Lyell teaches us to com- 

 prehend the meaning of them." But Lyell, though he did 

 not, like Sedgwick and Murchison, add new chapters to 

 geological history, nevertheless left his mark upon the 

 nomenclature and classification of the geological record. 

 Conceiving, as far back as 1828, the idea of arranging the 

 whole series of Tertiary formations in four groups, accord- 

 ing to their affinity to the living fauna, he established, 

 in conjunction with Deshayes, who had independently 

 formed a similar opinion, the well-known classification 

 into Eocene, Miocene, and Pliocene. The first of these terms, 

 as we all know, was proposed for strata containing an 

 extremely small proportion of living species of shells ; the 

 second for those where the percentage of recent species 

 was considerable, but still formed the minority of the 

 whole assemblage, while the third embraced the formations 

 in which living forms were predominant. The scheme 

 was a somewhat artificial one, and the original percent- 

 ages have had to be modified from time to time, but the 

 terms have kept their place, and are now firmly planted in 

 the geological language of all corners of the globe. 



Charles Darwin (1809-1882) contributed many valuable 

 works to the literature of geology. But it is not for these 

 that I cite his name on the present occasion. His two 



