APPENDIX D. GEOLOGY. 155 



globe ; and the one on Red river seems to me to be on a more gigantic 

 scale than any of which I have found a description. You seem in doubt 

 whether this gorge was worn away by the river, or is the result of some 

 paroxysmal convulsion. You will allow me to say that I have scarcely 

 any doubt that the stream itself has done the work. The fact that 

 when a tributary stream enters the main river it passes through a trib- 

 utary caiion, seems to me to show conclusively that these gorges were 

 produced by erosion, and not by fractures; for, how strange would it 

 be if fractures should take those ramifications and curvatures which a 

 river and its tributaries present. And, moreover, I find cases where I 

 can prove, from other considerations, that streams of water (existing 

 and ancient rivers) have eaten out gorges quite as difficult to excavate 

 as any of the carious of the West. So that, if we must admit that rivers 

 have done a work equally great in one case, all presumption is removed 

 against their doing the same in other cases. I have a great number of 

 facts, which I hope to be able, if life be spared, to present to the public 

 on this subject ; and I am very glad to add the canons of Red river to 

 the number. 



Before Professor Adams's departure for the West Indies last winter, I 

 secured his report, hereto subjoined, upon the recent shells collected in 

 your expedition. It derives a melancholy interest from having been 

 among the last, if not the very last, of his scientific efforts, he having 

 been cut off by yellow fever in January. 



With this imperfect elucidation of the facts collected by you in your 

 laborious explorations, I subscribe myself, 



With greatjrespect, 



Your obedient servant, 



EDWARD HITCHCOCK. 



Amherst College, June 5, 1853. 



