496 . GEOLOGY OF CENTRAL WISCONSIN. 



on the weathered kinds. This dark-colored rock is distinctly magnetic, feet. 

 affecting the needle, and adhering to a magnet in quite coarse particles. 

 An averaged sample yielded 32.1 per cent, of iron. A partial analysis of 

 the same material yielded the writer, in 1872, the following results: 



Per cents. 



Metallic iron 31 .87 



Silica 45.72 



Lime 1 .62 



Alumina 8.56 



Magnesia trace. 



Still another sample, averaged from the whole opening, and from the 

 stock pile outside, yielded 37.18 per cent, of metallic iron. The horizontal 

 width of this schist seen on the river is 60 



VI. Magnesian schist: similar to No. Ill; bedding very plain; strike N. 50 W., 



dip 60 N. E. ; width 20 



VII. Covered. In this interval the west side of the river begins to rise, the cnst 



side being now depressed into the valley of Levins' creek. On each side of 

 the mouth of this creek, and extending up it for a long distance, are -ledges 

 of thin-bedded, horizontal sandstone, which thus overlies and conceals the 

 Archaean rocks, filling the depressions in their ancient eroded surface. 

 The Archsean exposures are now transferred to the west side of the river. 

 The horizontal width of this gap at right angles to the general strike, is . . 100 



VIII. Magnesian schist: light-colored; silicious; similar to No. VI; showing 

 plainly the same bedding structure; width 40 



IX. Ferruginous quartz- schist (513): fine-grained, dark-gray, very quartzose; 



showing under the lens numerous grains of glassy, quartz, which occur 

 more abundantly on some seams than others. Seams and surfaces stained 

 red; non-magnetic; contains. 26.98 per cent, metallic iron; strike N. 45 

 W.; width 24 



X. Magnesian schist (511,512): in the lower or more southern portions quite soft 



(512); light greenish-gray, and without indication of any quartzose ingre- 

 dient; towards the upper portions becoming much more quartzose (511), 

 losing the softness and greenish tinge. In these last, the lens reveals 

 much granular, glassy, translucent and smoky quartz between the laminae; 

 width 200 



XI. Covered 120 



XII. Magnesian schist (504): greenish gray; having thin intercalated bands of 



ferruginous quartz-schist; width 120 



XIII. Ferruginous quartz- schist: very much weathered. An old pit has been 

 sunk on this near the water's edge. The loose material in the pit yielded 

 30.23 per cent, metallic iron. The width seen is 60 



Nos. XII and XIII are well exposed in the railroad cutting at the top of 

 the bank, about 80 feet high, at whose foot the pit alluded to is sunk. The 

 cutting is not quite in the line of strike, being nearly north and south. In 

 it are exposed, beginning at the north end (a) magnesian schist (508), 6 

 feet horizontal width; (b) banded ferruginous quartz schist, containing 

 29.17 per cent, of metallic iron, 2 feet; (c) magnesian schist with thin 

 seams of ferruginous quartz-schist, 13 feet; (d) ferruginous quartz- schist, 

 with small seams of magnesian schist the more ferruginous portions con- 

 taining 26.04 per cent, of iron 16 feet; (e) the same as the last, but con- 

 taining more magnesian bands, grading into the next layer, 16 feet; (f) 

 ferruginous schist, with many magnesian bands, cut into small prismatic 



