132 Wisconsin Academy of /Sciences, Arts, and Letters. 



caused by reflection from tlie cliffs above, togetlier with tlie 

 liigli winds of Wisconsin, is quite sufficient to account for its 

 maintenance of level ; wliilst tlie character of tlie surrounding 

 rock shows readily the reason for its not becoming saline. 



The great exposures of cliff at this locality, and the deep rock 

 cuttings on the newly-opened railroad, afford most excellent 

 opportunities for study. The change of direction, too, of the 

 valley, gives facilities for approaching the rocks from different 

 sides, not elsewhere easily obtainable. 



The rock here is mainly a hard, dark-colored, very compact 

 quartzite, though the colors vary from a very light gi-ey in 

 places to deep brownish-red. The bedding joints of the 

 quartzite are in some places rather obscure, but the railroad 

 cuttings have so far exposed them, that with a little care I was 

 able readily to ascertain the dip. This on both sides, and 

 throughout the whole length, of the valley, is uniformly about 

 20 to 25 degrees a little west of north. Some of the writers 

 mentioned, and notably Winchell, have described this valley as 

 corresponding to an old anticlinal axis, but the uniform dip of 

 the strata throughout its length proves, of course, that this is 

 not the case. 



Section 1.— North and south through the south range on section line 1 of map. A, 

 quartzites ; A', quartzites with some schists ; C, conglomerate ; S. P., Sauk Prairie ; B. V ., 

 Baraboo Valley ; L, level of lake. 



The quartzite, although often looking massive, shows in 

 many places, on weathered surfaces, the lamination and cross- 

 lamination of more modem sandstones. Many of the fallen 

 masses show, too, on exposed surfaces of lamination, the most 

 distinct ripple markings I have ever seen. On the shallow 

 sandy bottom at the north end of the lake below, may be found 

 their very counterparts. Between the beds of quartzite, in 



