20 



WISCON-SIN ACADEMY SCIENCES, ARTS, AST) LETTERS. 



In digging for the turn-table at the Green Baj^ and Min- 

 nesota depot, at Grand Rapids, a few lay- 

 ers of compact sandstone were first pene- 

 trated, this giving place suddenly to a 

 white kaolin through which piles had to 

 be driven five or six feet (?) before becom- 

 ing firmly placed. 



Immediately north of the Rablin House, 

 at Grand Rapids, kaolin is exposed in the 

 cut made for grading the street, which 

 here runs immediately along the river bank. 

 The following section was obtained at this 

 point — Fig. 1 — :* 



The decomposed rock is in most places 

 quite firm, though often a soft clay. It is 

 all whitish, and without any appearance of 

 the unaltered rock except the lamination. 

 A specimen of the former kind yielded : 



xir 



Potash 7.56 



Soda 5.03 



Water 3.55 



The decomposition had not 3^et removed 

 much of the alkalies, although the rock 

 was quite white. 



On lot 5, section 24, town 22, range 5 east, on the west side of the 

 river, on the land of Mr. L. P. Powers, kaolin occurs in the river bank. 

 The clay has been dughere to a considerable extent. It shov/s here 

 as elsewhere every degree of decomposition. The pure white is of 

 inconsiderable thickness before a firmer rocky kind is reached. At 

 the waters edge below are seen ledges of unchanged rock. At the 

 time of my examination the locality had been less developed than 

 since that time; but the several outcrops along the river bank in- 

 dicated a considerable quantity. From this place all of the clay 

 that has been shipped away from Grand Rapids has been taken. 

 Places were noticed here where bunches of highly ferruginous clay 



* The engraver has omitted the word "kaolin," m Fig. 1, underneath "sand- 

 stone," and also the word "gneiss " after "decomposed."' "Unaltered gneis" 

 should read, " unaltered gneiss.-' 



