346 Darwin and Geology 



certainly have done) "on no account to accept the views therein 

 advocated 1 ." It is probable that the days of waiting, discomfort 

 and sea-sickness at the beginning of the voyage were relieved by the 

 reading of this volume. For he says that when he landed, three 

 weeks after setting sail from Plymouth, in St Jago, the largest of the 

 Cape de Verde Islands, the volume had already been "studied 

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

 ways...." His first original geological work, he declares, "showed me 

 clearly the wonderful superiority of Lyell's manner of treating 

 geology, compared with that of any other author, whose works I had 

 with me or ever afterwards read 2 ." 



At St Jago Darwin first experienced the joy of making new 

 discoveries, and his delight was unbounded. Writing to his father 

 he says, " Geologising in a volcanic country is most delightful ; 

 besides the interest attached to itself, it leads you into most beautiful 

 and retired spots 3 ." To Henslow he wrote of St Jago: "Here we 

 spent three most delightful weeks.... St Jago is singularly barren, 

 and produces few plants or insects, so that my hammer was my 

 usual companion, and in its company most delightful hours I spent." 

 "The geology was pre-eminently interesting, and I believe quite 

 new ; there are some facts on a large scale of upraised coast (which 

 is an excellent epoch for all the volcanic rocks to date from), that 

 would interest Mr Lyell 4 ." After more than forty years the memory 

 of this, his first geological work, seems as fresh as ever, and he wrote 

 in 1876, "The geology of St Jago is very striking, yet simple: a 

 stream of lava formerly flowed over the bed of the sea, formed of 

 triturated recent shells and corals, which it has baked into a hard 

 white rock. Since then the whole island has been upheaved. But 

 the line of white rock revealed to me a new and important fact, 

 namely, that there had been afterwards subsidence round the craters, 

 which had since been in action, and had poured forth lava 5 ." 



It was at this time, probably, that Darwin made his first attempt 

 at drawing a sketch-map and section to illustrate the observations he 

 had made (see his Volcanic Islands, pp. 1 and 9). His first im- 

 portant geological discovery, that of the subsidence of strata around 

 volcanic vents (which has since been confirmed by Mr Heaphy in 

 New Zealand and other authors) awakened an intense enthusiasm, 

 and he writes : " It then first dawned on me that I might perhaps 

 write a book on the geology of the various countries visited, and 

 this made me thrill with delight. That was a memorable hour to me, 

 and how distinctly I can call to mind the low cliff of lava beneath 

 which I rested, with the sun glaring hot, a few strange desert 



1 L. L. i. p. 73. 2 L. L. i. p. 62. 3 L. L. i. p. 228. 



4 L. L. i. p. 235. e L Lm j p 65 



