Age of the Quarizites^ jSchists, Etc., oj Sauk Co. 131 



Science and Art (II, vol. xxxvii, p. 226) an article by Mr. 

 Alexander Wincliell of Michigan, in wliich lie describes, among 

 others, some fossils fi'om the conglomerates overlying the 

 qnartzites ; and npon them bases his claim that the quartzites 

 are a downward continuation of the Potsdam sandstones. He 

 himself never visited the localities. Finally, Mr. James H. . 

 Eaton of Beloit College, in a paper read before the Wisconsin 

 Academy of Science, in February, 1871, expresses the same 

 opinion though on somewhat different grounds. The foregoing 

 list includes everything of any value that has been published 

 on the subject. 



The accompanying map includes those portions of the two 

 ridges where most of my observations have been made. 



I. The South Eange, to which my attention was first 

 directed, presents, on approaching it from Sauk Prairie on the 

 south, a bold, and, in places, precipitous rise from the plain of 

 from 350-450 feet. The northern side of this ridge has how- 

 ever, in all places as yet studied, a much more gradual slope 

 down to the valley of the Baraboo river, this slope being in 

 many places determined by the northward dip. Punning en- 

 tirely through this ridge is a deeply cut valley, which has at 

 first for about two miles, a direction slightly north of west, 

 and then turns due north quite abruptly. This northern end 

 holds the Devil's Lake, which entirely fills the valley from 

 side to side. Throughout its whole length the sides of this 

 cleft are precipitous masses of quartzite rising everywhere more 

 than four hundred feet above the bottom, and reaching at the 

 lake an altitude of 501 feet above its level, and of 1,474 feet 

 above the sea. The bottom of the valley is covered with a 

 heavy mass of Drift material, and the lake is held in its position 

 by low Drift hills at its northern and southeastern extremities. 

 The bottom of the lake itself seems to be in a Drift sand, and 

 is over most of its area about thirty feet below the surface of 

 the water. The lake has no outlet ; but draining as it does 

 a very small amount of surface, the extraordinary evaporation 



