PEE FACE 



TO 



THE SECOND EDITION, 



The First Edition of my ' Geological Observations on 

 the Volcanic Islands/ visited during the voyage of 

 H.M.S. ' Beagle,' under the command of Capt. Fitz- 

 Roy, R.N., was published, with the approval of the 

 Lords Commissioners of Her Majesty's Treasury, in the 

 year 1844 ; and my ' Observations on South America,' 

 in 1846. As both these works are now out of print, and 

 as I believe that they still contain matter of scientific 

 value, it has appeared to me advisable that they should 

 be republished. They relate to parts of the world 

 which have been so rarely visited by men of science, 

 that I am not aware that much could be corrected or 

 added from observations subsequently made. 



Owing to the great progress which Geology has 

 made within recent times, my views on some few points 

 may be somewhat antiquated ; but I have thought it 

 best to leave them as they originally appeared. In 

 order to complete my account of the Geological Obser- 



