Concentration on Geological Work 355 



had " been incessantly attending to the effects on the shores of South 

 America of the intermittent elevation of the land, together with 

 denudation and the deposition of sediment 1 ." 



On arriving at the Cape of Good Hope in July, 1836, Darwin 

 was greatly gratified by hearing that Sedgwick had spoken to his 

 father in high terms of praise concerning the work done by him in 

 South America. Referring to the news from home, when he reached 

 Bahia once more, on the return voyage (August, 1836), he says : 

 "The desert, volcanic rocks, and wild sea of Ascension... suddenly 

 wore a pleasing aspect, and I set to work with a good-will at my old 

 work of Geology 2 ." Writing fifty years later, he says: " I clambered 

 over the mountains of Ascension with a bounding step and made the 

 volcanic rocks resound under my geological hammer 3 ! " 



That his determination was now fixed to devote his own labours 

 to the task of working out the geological results of the voyage, and 

 that he was prepared to leave to more practised hands the study of 

 his biological collections, is clear from the letters he sent home at 

 this time. From St Helena he wrote to Henslow asking that he 

 would propose him as a Fellow of the Geological Society; and his 

 Certificate, in Henslow's handwriting, is dated September 8th, 1836, 

 being signed from personal knowledge by Henslow and Sedgwick. 

 He was proposed on November 2nd and elected November 30th, 

 being formally admitted to the Society by Lyell, who was then Presi- 

 dent, on January 4th, 1837, on which date he also read his first 

 paper. Darwin did not become a Fellow of the Linnean Society till 

 eighteen years later (in 1854). 



An estimate of the value and importance of Darwin's geological 

 discoveries during the voyage of the Beagle can best be made when 

 considering the various memoirs and books in which the author 

 described them. He was too cautious to allow himself to write his 

 first impressions in his Journal, and wisely waited till he could study 

 his specimens under better conditions and with help from others on 

 his return. The extracts published from his correspondence with 

 Henslow and others, while he was still abroad, showed, nevertheless, 

 how great was the mass of observation, how suggestive and pregnant 

 with results were the reasonings of the young geologist. 



Two sets of these extracts from Darwin's letters to Henslow 

 were printed while he was still abroad. The first of these was the 

 series of Geological Notes made during a survey of the East and 

 West Coasts of South America, in the years 1832, 1833, 1834 and 

 1835, with an account of a transverse section of the Cordilleras of 

 the Andes between Valparaiso and Mendoza. Professor Sedgwick, 

 who read these notes to the Geological Society on November 18th, 



1 L. L. i. p. 70. J L. L. i. p. 265. s L. L. i. p. 66. 



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