sou EXPEDITION- TO THE 



course, which approaches to a north-west direction, obliges 

 us to cross all these ridges and valleys nearly at right an- 

 gles. No granitic blocks are to be seen ; this is accounted 

 for by the fact that we are no longer upon the alluvial for- 

 mation, but upon the magnesian limestone which rises to 

 a greater height, constituting the dividing ridge between 

 the Mississippi, Rock river, and the Wisconsan, and per- 

 haps connecting itself with what have been termed the 

 Wisconsan hills. 



The features, which we observed from the Wassemon to 

 the Wisconsan, are extremely interesting. At a distance of 

 a few miles north-west of the former stream, the vegeta- 

 tion presented a sudden and striking change, announcing a 

 corresponding one in the geological character of the coun- 

 try. We ascended a rough, steep, and hilly ground, which 

 was covered with heavy timber, and with a very thick 

 underwood, consisting principally of young oak and aspen. 

 This thick brush-wood continued for about two miles, 

 when we struck the bank of a small stream, remarkable for 

 the beauty of its scenery, which differed from any that we 

 had hitherto met with. The brook runs in a deep and narrow 

 glen, the sides of which are very steep and in some places 

 vertical ; they are covered at their summit with a dense vege- 

 tation, which extends over the edge of the rock, and imparts 

 a character of austerity and of gloom to this secluded valley, 

 which finds not its parallel in any that we recollect having 

 ever seen. The dark colour, which the water receives from 

 the deep shadows cast by the high steep bank and its over- 

 hanging vegetation, forms a pleasing relief to the glare, so 

 uniformly fatiguing, of the unsheltered prairie. This spot 

 conveyed so much relief to the eye and to the mind, that 

 the party could not repress their delight on beholding it. 

 The geologist who connects a change in the nature of the 



