512 GEOLOGY OF CENTRAL WISCONSIN. 



rise of over a hundred feet. The summit is of bare rock, and is a mere crest, others 

 similar to it occurring' east and west along the range. The bedding of the quartzite is 

 distinct, the strike being N. 63 E., and dip 60 N. 



On Sees. 34, 35, 26 and 27, T. 12, R. 8 E., numerous other large quartzite exposures 

 occur. On the S. E. qr. of Sec. 27, large outcrops on the roadside show pinkish -gray, 

 opaque quartzite (755) with very fine greenish-black streaks (Mica?). 



The eastern end of the quartzite ranges is on Sec. 25, T. 12, R. 8 E., where the 

 two ranges -unite in the bold point that has been heretofore alluded to. On the north 

 side of the point the horizontal sandstone begins again to flank the quartzite. On the 

 N. W. qr. of Sec. 25, the road ascending the bluff shows sandstone, with a slight slant 

 eastward, nearly to the top. Near by, on the S. E. qr. of N. E. qr. of Sec. 26, are large 

 rounded exposures (roches montonees) of quartzite showing on the top glacial furrows 

 and scratches, and also several large smoothed potholes, the largest two feet wide and 

 one foot deep, with connecting furrows. Occurring where no stream could now possibly 

 run, these potholes are of interest as showing the great erosion the quartzite must ha,ve 

 undergone since their formation. 



Along the northern side of the north range and westward from the eastern ex- 

 tremity, the flanking sandstone continues nearly to the county line. On the south side 

 of section 23, well up on the bluff, a steep ravine has laid bare the sandstone and quartz- 

 ite nearly in contact, as shown in Fig. 28. The quartzite here (753) is a fine metamor- 



FIG. 28. 





UNCONFORMABILITY, SEC. 23. CALEDONIA. 



phic conglomerate, in which the matrix of pinkish-white quartz embraces darker-hued 

 pebbles T V inch to \ inch in diameter. The pebbles are very firmly attached to the 

 matrix, and are not always well defined from it. Nests and veins of white quartz (754) 

 occur in this rock. 



On the N. E. qr. of sec. 22, T. 12, R. 8 E., a deep ravine shows a great thickness of 

 sandstone, with a bed of bowlder conglomerate, dipping northward, or away from the 

 qnartzite. Further westward along the road from Portage to Baraboo, which follows 

 the foot of the bluff, sandstone is seen in numerous places. On the N. W. qr. of Sec. 21, 

 high up on the bluff, a well goes through 10 feet of sandstone and then into quartzite. 

 It is quite probable that the quartzite core is in places along here entirely covered by 

 Siindstone. The core does not extend, however, beyond the southern line of sections 19, 

 20, and 21, for here wells pass through over 170 feet of sandstone. After passing the 

 county line, the north slope of the quartzite is again free from its sandstone mask, and 

 is to be seen in small outcrops dipping N. 60. 



