568 GEOLOGY OF CENTRAL WISCONSIN. 



20, R. 6 E., 13 miles north of Roche a Cris; Petenwell Peak, a very narrow bluff 230 

 feet high, and with serrated crest, on the west shore of the Wisconsin, Sec. 9, T. 18, R. 

 4 E.; the group of bluffs 6 to 8 miles south of Friendship; the large wooded bluft'6 

 miles southeast of Mauston, T. 15, R. 4 E.; and the Elephant's Back, near Kilbourn 

 City. The last two, though high, do not stand out very prominently, as seen from 

 points within the plain, on account of their nearness to the high ground that limits it on 

 the south. The quartzite bluff at Necedah is also quite prominent. Of the smaller 

 sandstone outliers there are a great number and variety. Many of them are simple 

 peaks or towers of rock, having a diameter at base of only a few feet, and 40 to 60 feet 

 in height, in some cases the diameter at base being less than that at the summit. Oth- 

 ers are a series of pinnacles or rounded towers joined together, and others again are 

 massive bluffs with wooded summits and perpendicular sides of rock. 



The high ground that bounds the plain on the west enters Juneau county on the west 

 side of T. 16, R. 2 E. (Fountain), carrying on the county line a capping of the Lower 

 Magnesian limestone. From here it trends southeastward across the towns of Foun- 

 tain, Plymouth, Lindina, Wonewoc and Summit, reaching elevations of 500 to 600 feet, 

 and then, veering more to the eastward, across the towns of Seven Mile Creek and Lyn- 

 don to the Wisconsin river, where it is cut through by that stream in the gorge known 

 as the Dalles of the Wisconsin. This ridge is very well marked on its northern side, 

 rising abruptly from the plain, towards which it presents a face deeply indented by the 

 streams flowing northward from it, and flanked by isolated outliers of sandstone. Until 

 it nears the Wisconsin, it constitutes the divide between the waters of the Baraboo 

 and Lemonweir rivers. The former of these streams enters Juneau county on the west 

 line of the town of Plymouth, through which, as also through the next town on the 

 south, it passes in a nearly southerly direction to the south line of the county, having all 

 along a narrow rock- walled valley, into which tributary streams come through deep 

 ravines, that set back into the higher ground on each side. Thus throughout all of these 

 southwestern towns of Juneau, the country bears quite a different aspect from that of 

 other portions of the county, being, in general, an elevated region, carved into numer- 

 ous ravines, and presenting, on the higher portions, a very excellent clay soil, although 

 entirely without the drift area. As the Dalles are approached, the ridge lessens in 

 elevation, and shows on its northern side many sandstone escarpments, which are often 

 worn into fantastic ."hapes. East of the Wisconsin, the encircling high ground 

 continues, curving rapidly to the northeast and north, through the towns of Dell Prairie 

 Sprmgville, Jacks6n and New Chester, running thence northward along the east line 

 of Adams county, and reaching elevations of 200 to 300 feet above the Wisconsin river. 

 Its character, however, is now quite changed, the slopes being no longer abrupt nor 

 worn into ravines, whilst the whole surface is heavily drift-covered. 



The plain, thus encircled by high ground, would, over the greater part of its area, be- 

 come covered by water, if the gorge at the Dalles were closed. That such may actually 

 have been the case at some time, is indicated by the general appearance of the plain and 

 its surroundings, bj its numerous large marshes, by the finely laminated (lacustrine?) 

 clay deposits that occur in places over it, and by the great bank of rolled pebbles and 

 bowlders of quartzite that flanks the quartzite bluff at Necedah, far within the driftless 

 region. 



In the valley of the Upper Baraboo, and on the adjoining high ground, in the 

 t)wns of Fountain, New Lisbon, Plymouth, Lindina, Wonewoc and Summit, Juneau 

 county, the sandstone is frequently exposed. The immediate valley of the river is nar- 

 row, and frequently bounded by rock walls, 20 to 120 feet in height, which show gen- 

 erally rather friable, medium-grained, brownish to white, sandstone, without trace of 

 calcareous or dolomitic ingredients. In places, as on the east side of the river at Elroj-, 

 near the railroad bridge, firm quarry layers occur. The high ground on either side of. 



