X 



first time at St. Jago, in the Cape de Verd Islands, and Darwin 

 found his attention vividly engaged by the volcanic phenomena and 

 the signs of upheaval which the island presented. His geological 

 studies had already indicated the direction in which a great deal 

 might be done, beyond collecting ; and it was while sitting beneath 

 a low lava cliff on the shore of this island, that a sense of his real 

 capability first dawned upon Darwin, and prompted the ambition 

 to write a book on the geology of the various countries visited. 

 (I, p. 66.) Even at this early date, Darwin must have thought 

 much on geological topics, for he was already convinced of the 

 superiority of Lyell's views to those entertained by the catastro- 

 phists* ; and his subsequent study of the tertiary deposits and 

 of the terraced gravel beds of South America was eminently fitted 

 to strengthen that conviction. The letters from South America 

 contain little reference to any scientific topic except geology ; and 

 even the theory of the formation of coral reefs was prompted by the 

 evidence of extensive and gradual changes of level afforded by the 

 geology of South America; "No other work of mine," he says, 

 " was begun in so deductive a spirit as this ; for the whole theory was 

 thought out on the West Coast of South America, before I had seen 

 a true coral reef. I had, therefore, only to verify and extend my 

 views by a careful examination of living reefs." (I, p. 70.) In 1835, 

 when starting from Lima for the Galapagos, he recommends his 

 friend, W. D. Fox, to take up geology : — " there is so much larger a 

 field for thought than in the other branches of Natural History. I 

 am become a zealous disciple of Mr. Lyell's views, as made known in 

 his admirable book. Geologising in South America, I am tempted to 

 carry parts to a greater extent even than he does. Geology is a 

 capital science to begin with, as it requires nothing but a little read- 

 ing, thinking, and hammering." (I, p. 263.) The truth of the last 

 statement, when it was written, is a curious mark of the subsequent 

 progress of geology. Even so late as 1836, Darwin speaks of being 

 " much more inclined for geology than the other branches of Natural 

 History." (I, p. 275.) 



At the end of the letter to Mr. Fox, however, a little doubt is 

 expressed whether zoological studies might not, after all, have been 

 more profitable ; and an interesting passage in the Autobiography 

 enables us to understand the origin of this hesitation. 



"During the voyage of the ' Beagle ' I had been deeply impressed- 



* " I had brought with me the first volume of Lyell's ' Principles of G-eology,' 

 which I studied attentively ; and the book was of the highest service to me in many 

 ways. The very first place which I examined^ namely, St. Jago in the Cape de 

 Verd Islands, showed me clearly the wonderful superiority of Lyell's manner of 

 treating G-eology, compared with that of any other author whose works I had with 

 me or ever afterwards read." (I, p. 62.) 



