KAOLIIsr IN WISCOITSIN. 



23 



Kaolin on Yellow River. — Kaolin is reported in quantity on Yel- 

 low River. The localities are above Dexterville in Wood county. 

 The Archaean rocks are exposed finely 

 for many miles along the bed of the 

 stream. They show everywhere a ten- 

 dency to weather, consisting largely 

 of a pinkish felspar. In places I no- 

 ticed the weathering carried to the 

 condition of clay, but did not see any 

 of the white clay that is said to exist. 



Kaolin on Black River. — On this 

 stream, in Jackson county, kaolin oc- 

 curs between Black River Falls and 

 Black River Station. As on the Wis- 

 consin, the Archaean rocks are found 

 here forming the bed of the stream, 

 the sandstone overlying them in the 

 banks. In many places the gneissic 

 rocks are decomposed. At the lower 

 end of the rapids at the town of Black 

 River Falls, the gneisses disappear be- 

 neath the sandstone. A section very 

 like that on the Wisconsin, at Point 

 Bas, occurs here; and exhibits the 

 mode of formation of the kaolin hand- 

 somely. 



On the west bank of the river at 

 Ledyard's old mill, is a high cliff of 

 sandstone overlying gneiss, (Fig. 3.,) 

 the exposures of both rocks extend- 

 ing several hundred feet. The surface 

 of the gneiss is irregular, its de- 

 pressions being filled by the over- 

 lying sandstone. The gneiss is very 

 distinctly seamed — the seams striking 

 north 37 degrees west, (magnetic,) and 

 dipping southwest about sixty de- » 



grees — is moderately coarse, micace- 

 ous, and has much pinkish orthoclase felspar, which occurs some- 



r 



lo 



