'GEOLOGICAL OBSERVATIONS.' 295, 



writers to recognize the magnitude of the denudation to which 

 even recent geological accumulations have been subjectedo 

 One of the most impressive lessons to be learnt from his ac- 

 count of ' Volcanic Islands ' is the prodigious extent to which 

 they have been denuded. ... He was disposed to attribute 

 more of this work to the sea than most geologists would now 

 admit ; but he lived himself to modify his original views, and on 

 this subject his latest utterances are quite abreast of the time." 



An extract from a letter of my father's to Lyell shows his 

 estimate of his own work. " You have pleased me much by 

 saying that you intend looking through my ' Volcanic Isl- 

 ands ' : it cost me eighteen months ! ! ! and I have heard of 

 very few who have read it. Now I shall feel, whatever little 

 (and little it is) there is confirmatory of old work, or new, 

 will work its effect and not be lost." 



The third of his geological books, ' Geological Observa- 

 tions on South America,' may be mentioned here, although it 

 was not published until 1846. " In this work the author em- 

 bodied all the materials collected by him for the illustration 

 of South American Geology, save some which have been pub- 

 lished elsewhere. One of the most important features of the 

 book was the evidence which it brought forward to prove the 

 slow interrupted elevation of the South American Continent 

 during a recent geological period."* 



Of this book my father wrote to Lyell : " My volume will 

 be about 240 pages, dreadfully dull, yet much condensed. I 

 think whenever you have time to look through it, you will 

 think the collection of facts on the elevation of the land and 

 on the formation of terraces pretty good." 



Of his special geological work as a whole, Professor Geikie, 

 while pointing out that it was not " of the same epoch-making 

 kind as his biological researches," remarks that he " gave a 

 powerful impulse to " the general reception of Lyell's teach- 

 ing " by the way in which he gathered from all parts of the 

 world facts in its support." 



* Geikie, loc. at. 



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