THE LOWER SILURIAN ROCKS. 



591 



Fig. 45 is a section across the valley of the Wisconsin from the high bluff just west of 

 RowelTs Mill, N. W. qr. Sec. 17, T. 9, R. 6 E., Prairie da Sac, in a N. 68 E. direc- 

 tion to the blutf's back of Clifton, Dane county. 



Fig. 45. 



SECTION ACROSS THE VALLEY OP THE WISCONSIN, AT PRAIRIE DU SAC. 

 Vertical scale 400 feet, 1 inch; horizontal scale \y % miles, 1 inch. 



The very bold and prominent bluff rising from the bank of the Wisconsin at the 

 mouth of Honey creek, Sec. 21, T. 9, R. 6 E., has already been cited as giving a mag- 

 nificent section, and portions of this section have been given in some detail in the gen- 

 eral descriptions of the formation. Abbreviated, the section is as follows : 



Ft. In. 

 .1. Lower Magnesian, in a vertical cliff facing towards Honey Creek, including. 



subdivisions as given on page 552 52 5 



2. Madison, including: slope without exposure, 15 feet; white and brown sand- 



stone for the most part non-calcareous, 16.5 feet; slope without exposure, 



7 feet; coarse, non-calcareous white and brown sandstone, 2 feet; in all 40 5 



3. Mendota, including : slope without exposure, 33 feet; brown, earthy, very coin- 



pact limestone with 34.15 per cent, of white clay, 1 foot; like the last, 



but with 26 per cent, of clay, 2^ feet; in all 36 6 



4. Potsdam, including subdivisions as given on page 534; rising abruptly from 



the Wisconsin , 189 3 



Total height of bluff 318 7 



Altitude of summit 484 . . 



HONEY CREEK BLUFF 



Fig. 46 is a section across the valley of the Wisconsin, from the bluff just described, 

 in a southeasterly direction to the bluff on Sec. 1, T. 8, R. 6 E. 



South of the quartzite 



FlG - 46 - range, over all of T. 10, 



R. 4 E., Honey Creek, 

 the country is one char- 



acterized by numerous 



,- 



m gh, narrow, branching 



ridges, which are. for 

 the most part, severed 



SECTION ACROSS THE WISCONSIN VALLEY TROM IIONEY" OREEK 

 BLUFF. 



Vertical scale 400 feet to the inch ; horizontal, 1V4 miles to the inch. 



parts, showing frequent- 



ly walls of bare rock, 



, 

 and often rising in- 



to the nonzon of ^0 

 Mendota beds, more 



rarely into that of the Lower Magnesian. In many cases, the sides of tho ridges arc 

 worn into bold and fantastic forms of bare rock, whose very plain horizontal stratifica- 

 tion renders the effect more striking. On the N. W. qr. of Sec. 17, T. 10, R. 5 E., a 

 narrow, precipitous spur from a higher bluff is worn entirely through, forming a natur>\ 



