136 THE VOYAGE. [Ch. VI. 



a week ago from my excursion across the Andes to Mendoza. 

 Since leaving England I have never made so successful a 

 journey; it has, however, been very expensive. I am sure 

 my father would not regret it, if he could know how deeply 

 I have enjoyed it : it was something more than enjoyment ; I 

 cannot express the delight which I felt at such a famous 

 winding-up of all my geology in South America. I literally 

 could hardly sleep at nights for thinking over my day's work. 

 The scenery was so new, and so majestic ; everything at an 

 elevation of 12,000 feet bears so different an aspect from that 

 in a lower country. I have seen many views more beautiful, 

 but none with so strongly marked a character. To a geologist, 

 also, there are such manifest proofs of excessive violence ; the 

 strata of the highest pinnacles are tossed about like the crust 

 of a broken pie. 



I do not suppose any of you can be much interested in 

 geological details, but I will just mention my principal 

 results: — Besides understanding to a certain extent the 

 description and manner of the force which has elevated this 

 great line of mountains, I can clearly demonstrate that one 

 part of the double line is of an age long posterior to the other. 

 In the more ancient line, which is the true chain of the Andes, 

 I can describe the sort and order of the rocks which compose 

 it. These are chiefly remarkable by containing a bed of 

 gypsum nearly 2000 feet thick — a quantity of this substance I 

 should think unparalleled in the world. What is of much 

 greater consequence, I have procured fossil shells (from an 

 elevation of 12,000 feet). I think an examination of these will 

 give an approximate age to these mountains, as compared to 

 the strata of Europe. In the other line of the Cordilleras 

 there is a strong presumption (in my own mind, conviction) 

 that the enormous mass of mountains, the peaks of which rise 

 to 13,000 and 14,000 feet, are so very modern as to be con- 

 temporaneous with the plains of Patagonia (or about with 

 the upper strata of the Isle of Wight). If this result shall be 

 considered as proved,* it is a very important fact in the theory 

 of the formation of the world ; because, if such wonderful 

 changes have taken place so recently in the crust of the globe, 

 there can be no reason for supposing former epochs of ex- 

 cessive violence 



Another feature in his letters is the surprise and delight 

 with which he hears of his collections and observations being 



* The importance of these results has been fully recognized by 

 geologists. 



