14:4: THE VOYAGE. [ch. vi. 



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 re- 

 sults : Besides understanding to a certain extent the de- 

 scription 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 con- 

 taining 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 fos- 

 sil 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 contemporaneous 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 excessive vio- 

 lence 



Another feature in his letters is the surprise and delight 

 with which he hears of his collections and observations be- 

 ing of some use. It seems only to have gradually occurred 

 to him that he would ever be more than a collector of speci- 

 mens and facts, of which the great men were to make use. 

 And even as to the value of his collections he seems to have 

 had much doubt, for he wrote to Henslow in 1834 : " I 

 really began to think that my collections were so poor that 

 you were puzzled what to say ; the case is now quite on the 

 opposite tack, for you are guilty of exciting all my vain 

 feelings to a most comfortable pitch ; if hard work will 

 atone for these thoughts, I vow it shall not be spared." 



- ' - -- --. ... .,., , , , , -. _.._ _ ....,. _ _ , _ ^ 



* The importance of these results has been fully recognized by geologists. 



