194 Miscellanies. _ 



mains of the coralline family. Lower down, is a bituminous alu- 

 minous slate, sometimes mistaken for a part of the coal series, but 

 no coal is ever found beneath it. 



Still lower down, the rocks are very fossiliferous, and among 

 these rocks is a good hydraulic lime. There is a very good burr 

 stone, almost entirely made up of a series of fossil corallines, of- 

 ten cased in a sheath of drusy crystals of quartz. These burr 

 stones have served well as mill stones. The lowest limestone 

 beds are exceedingly rich in fossil shells and corallines ; the rock 

 is of a gray color, and when polished, forms a marble, adorned 

 by the organic remains. Near Indianapolis, and the great na- 

 tional road in that vicinity, the rock formations are covered by 

 diluvium, so thick that the deepest wells have not penetrated 

 through it : the same is the fact on the north side of the national 

 road. 



It appears that bowlder stones of primitive rocks are numerous 

 in Indiana, especially in the northern and prairie region of the 

 State ; they are called by the expressive name of lost rocks, also 

 gray heads, and negro heads. 



The northwest corner of Indiana is bounded by Lake Michi- 

 gan, which in this part has for its bed a stiff tenacious clay, and 

 still the water is so clear, that the fish, as in Lake George, can be 

 seen, in calm weather, at a great depth. The southern boundary 

 of the lake is composed of rolling ridges of siliceo-calcareous 

 sand, and it is remarkable that this sand, taken from thirty or 

 forty feet deep, will produce excellent potatoes, water-melons and 

 pumpkins : wild rye, six feet in height, and rank grass, are said 

 to have formerly grown at the top of the sand knobs, sixty or sev- 

 enty feet high : the mixture of the lime with the sand accounts 

 for this fertility. South of the national road, is found the com- 

 pact hydrated brown oxide of iron, of good quality : some of it is 

 in a conglomerate state, made up of fragments of the ore. There 

 is also carbonate of iron. 



At Troy is found a valuable material for pottery — the potters call 

 it marl — Mr. Owen, clay slate (slaty clay ? Ed.) It is hard when 

 first dug, but crumbles on exposure to the air. This furnishes the 

 raw material for the fire-brick, and saggers for a manufactory of 

 queen's ware and porcelain ; the clay for the latter is brought from 

 the clay banks on the Mississippi, (erroneously called the chalk 

 banks,) and near to the manufactory, there are good beds of pot- 



