468 GEOLOGY OF CENTRAL WISCONSIN. 



bedding-. A red felspathic vein was noted, 2 inches wide, dipping 70° N., and also the 

 same east and west quartz veins as before. Towards the northwest end of this ex- 

 posure the gneiss is quite thoroughly decomposed into a crumbling, earthy-textured, 

 brown- and white-blotched material, showing still a few nuoa flakes and quartz granules 

 in the interior, and containing 4.96 per cent, of water. The same paxtly kaohnized 

 rock is found all along the section until the west bank of the river is reached, showing, 

 Iwwever, still quite plainly the lamination and bedding planes of the unaltered rock, the 

 (hp and strike remaining the same. At the foot of the west bank, which is about 20 

 feet in height, unaltered quartzose granite shows, with north and south quartz veins }4 

 inch thick. Above this, and some few feet above the water level, fine, white, soft kaolin 

 shows in a httle swamp, and above this again are seen a few thm layers of the sand- 

 stone. 



On the N. W. qr. Sec. 10 are openmgs in the river bank, here some 20 feet in height, 

 showing a considerable quantity of white kaolin. The various exposures are at difler- 

 ent levels, and may indicate a thickness of as much as 1-5 feet m some place.", but as the 

 clay is merely an alteration of the gneissic rock in place, it forms no continuous bed, 

 tlie less altered portions of the rock occasionally rising entirely through it. At the 

 principal opening 22 inches of soft, bluish-white clay were noticed. The following are 

 analyses of samples from this place : 



861. 803. 



A B 



Potash 1.25 2.81 



Soda 08 trace 



Iron 2.88 



Water .... 8.69 



861 A is the raw kaolin from the lower part of the exposure; 861 B is the fine or ka- 

 oUnite portion of 861 A, separated by levigation. Nos. 862 A and 862 B are, in hke 

 manner, raw and washed clay fi-om the upper part of the same opening. The amounts 

 of alkalies are considerable, and no lessening in tlieh- percentages appears to be eft'ected 

 l)y levigation. The state of oxidation of the iron was not determined, but it would ap- 

 pear to be chiefly in the protoxide state, judging from the color of the clay. These facts 

 would indicate a less thorough kaohnization here than at other places in the vicinity. 

 Immediately above the kaolin openings are two feet of coarse, brownish, friable sand- 

 stone, whilst below it, down to the water's edge, gneiss in decreasmg stages of decom- 

 position is seen. At the foot of the bank is a low exposure of unaltered, fine-grained, 

 light-colored gneissoid granite (868). The three ingredients of the rock are all distinctly 

 visible, the felspar being l)oth pink and white, the latter without apparent stiiations; 

 the quartz is aljundant, in hyahne grains; the mica is aggregated into layers and pro- 

 duces a greasy feeling on some smi'aoes of lamination. 



At the foot of the rapids, on the west side of the Wisconsin, just above Port Edward, 

 on Sec. 25, T. 22, R. 5 E., a rather coarse grained, mottled, red-weathering gneissoid 

 granite (879) is exposed. A distinct parallel grain is perceptiljle, with corresponding 

 bedding joints, which strike N. 45° E. and dip 50° N. W. Other jomts, which make 

 large smooth faces, strike N. 75° E. About 50 feet further up stream is exposed a coarse- 

 grained, pinkish, highly felspathic rock, which shows a very cUstmct, sometimes con- 

 torted, lamination, trending in the same N. 45° E. direction as before. In this rock 

 the mica is nearly excluded by the felspar and quartz, which themselves are largely 

 separated into distinct bands. Jn places much pyrite is present. Fifty feet f nrther a 

 low exposure shows an apparent JS . 50° W . strike, but this seems to be dtie to numer- 

 ous close veins running in this direction, for a few feet beyond, the same strike direc- 

 tion as before observed reappears, accompanied now by a southeast dip, in a fiiip 



