THE ARCHJEAN ROCKS. 



479 



Exposure No. Ill of the map is on the road side in the S. W. qr. of the S. E. qr. of Sec. 

 8. The rock here is a fine-grained, light-pink, gneissoid granite (779), having the three 

 ingredients distinctly visible, though fine, and showing a few whitish kaolinized patches. 

 At No. IV of the map, are large exposures at the top of the bank and in the river be- 

 low. Fig. 13 shows the occurrences. 



FIG. 13. 



WfSt '': 



^^^^^;;^^^'^^^-^ 

 '- '*''< ; r' 



Scale, 30 feet to the inch. 



At A is a bold exposure of smooth-jointed, fine-grained, light-reddish granite (780), in 

 which red-stained granular quartz is the predominating ingredient, mica being very 

 subordinate, occurring in fine brilliant brownish flakes, and showing a slight tendency 

 towards a stringy arrangement. The numerous joints which traverse this rock strike 

 N. 17 W., and stand nearly vertical. At B (782) is a coarse-grained, red-and-black- 

 mottlcd, micaceous gneiss, striking plainly N. 59 E. This rock resembles that of No. 

 Ill, but contains much more reddish non-striated felspar. Whitish kaolinized patches 

 occur. Bounding this on the south, at C, and sharply defined from it, is a fine-grained, 

 dark-greenish crumbling rock (781), having a marked E. W. lamination. This rock 

 appears to contain, predominatingly, fine blackish mica, with which appears to be min- 

 gled some fine whitish felspar (mica-schist?). Little pinkish felspathic threads traverse 

 the rock. To the south of this again, at D, comes in a fine-grained, very compact, 

 greenish, gneissoid granite (783), striking N. 70* E. and showing as constituents, fine- 

 flaked, blackish mica, pink and white felspar, and limpid quartz. 



Passing now to the east side of the river, we note first on the N. E. qr. of the S. E. 

 qr. of Sec. 8, near the foot of the rapids, and just above the mouth of Plover river, 

 at No. V of the map, large, but low, outcrops of quartzose gneiss, bearing nearly 

 east and west, dipping south 60*, and overlaid by 25 to 35 feet of horizontal sandstone. 

 This point appears to be on the anticlinal line where the southeast dips of the Grand 

 Rapids series give place to the northeast dips of the Conant's and Stevens Point 

 rapids. 



On the N. E. qr. of the N. W. qr. of the same section (No. VI of map), large ex- 

 posures begin, which extend up stream for a long distance, and show all along a very 

 marked trend of N. 25 E. The southernmost rock examined here is a fine-grained, 

 dark-colored, highly micaceous gueiss, traversed by numerous large veins of reddish 



