QUATERNARY FORMATION'S THE DRIFT. 239 



Creek, Geneva, Kewaskum, Jfulheim, Two Elvers, Northelm, Center- 

 mile, and doubtless at other points that escaped our notice. 



Tiles, for draining, are manufactured at Whitewater, from a light 

 grayish blue clay, by Mr. A. Y. Chamberlin. Pottery is also made 

 at the same place from a clay obtained in the vicinity. 



The drift formations likewise furnish abundant beds of sand of ex- 

 cellent quality for building purposes, and of gravel suitable for roads 

 and other purposes. 



Magnetic Iron Sands. It has already been stated that the red 

 clay contains a notable amount of magnetite. As it is eaten away by 

 the lake, the grains of magnetite accumulate on the shore, and form 

 what is popularly known as "Black Sand." Occasionally a layer of 

 three or four inches of this may be found almost free from silicious 

 sand, but usually it is in thinner laminae, or mixed in varying pro- 

 portions with common sand. It exists in greater or less abundance 

 along the whole shore line, and the aggregate amount of it is large. 

 It has never been used for economic purposes, so far as I can learn, 

 except as " drying sand," before the era of blotting paper. Similar 

 accumulations are successfully utilized in the manufacture of steel in 

 other regions, and the value of this deposit may be worthy of consid- 

 eration. 



SHELL MARL. 



It will be most convenient to consider in this connection a fine de- 

 posit of shell marl that occurs in sections 17, 18, 19 and 20, town of 

 Pierce, T. 24, R. 25, Kewaunee county, around the margin of a small 

 lake, and upon a shoal within it, which, by recent drainage has become 

 an island. At some points it is mixed with peat and at others 

 with alluvium, but on this island -it is almost perfectly pure shell 

 debris. It is soft, light, porous and pulverulent on the surface. 

 "When brought up from beneath the water level, it is a soft, somewhat 

 granular and clay-like mass. A pole was thrust down nine feet with- 

 out giving any evidence of change in material. A specimen of this 

 iiarl gave on analysis by Mr. Bode, 



Carbonate of lime 86.09 



Carbonate of magnesia 7.18 



Silica 1 .48 



Oxide of iron and alumina 0.10 



Sulphuric acid 0.44 



Water 1 .67 



Organic matter 2.95 



100.00 



For lands deficient in lime this will furnish the needed fertilizer. 



