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 hebiie, and negro heads. 
The risctinrast oe 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-caleareous 
id, 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? Ep.) 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 neat to the manufactory, there are good beds of pot- 
