182 EXPEDITION TO THE 11^ 



though it were the most delicate food that he had ever 

 tasted. 



The valley of Rock river is about half a mile wide at 

 this place; it is utterly destitute of rocks, differing, in this 

 respect, very much from the characters observed higher 

 up, and which have entitled it to the name that it now 

 bears. We could not, however, ascertain whether the rocks 

 were there in place, or merely boulders. We had, in the 

 course of the morning, observed a spot where the lime- 

 stone appeared in situ ; this was in every respect similar to 

 that found near Chicago. The boulders and pebbles which, 

 from Chicago to Fox river, had not appeared to be as nu- 

 merous as in some other parts of the route, were, after we 

 had seen the limestone in the morning, found to increase 

 rapidly in number, though not perhaps in size. From his 

 former observations upontJ:ie country. Major Long thought 

 we were approaching what has been considered the lead 

 formation of the west, and this was confirmed by the as- 

 sertion of our guide, that much lead had been found on 

 some of the tributaries of Rock river, where it is worked, 

 by the Indians, in small quantities for their own use. This 

 induced us to make a careful examination of the country, 

 with a view to ascertain whether any lead ore occurred 

 upon our route, and if it did, under what circumstances. 

 We met with none ; but from all the characters observed 

 in the country, we hesitate not in considering its surface 

 as covered by an ancient alluvion, the alluvion of mountains 

 of the Wernerian school ; and in which, of course, if any 

 lead should be found, it must be out of its original site. 

 This alluvion consists principally of a bed of loose and un- 

 eemented pebbles, varying in size from the smallest grain 

 to the dimensions of an apple, and interspersed with boul- 

 ders, which frequently acquire very large dimensions; but 



