260 
f Assembly 
of its components. This circumstance is common j for example j to the 
lower layers; these layers being more compact, hard, and not so regu- 
lar in their outline, the lines of separation not being parallel, but waved 
and irregular, as though they had been unequally compressed, owing, 
no doubt, to the removal of their carbonate of lime, and the partial so- 
lution of their silicious material. 
With these layers, we often find coarse agate flint, silicious concre- 
tions and those round or ovoid bodies, also of silex, called oolite. — 
These various productions, with a number of other circumstances, prove 
that the materials of these layers had been subjected subsequently to 
their deposition, to a mechanical motion as well as a chemical action. 
Upon these layers, in many localities, there are others abounding in 
cavities, containing rock crystals and anthracite coal; the discovery, or 
presence of the latter, having excited in many localities no small ex- 
pectation of realizing by excavation, important beds of this material. 
The coal is often enveloped by the crystals, and often presents those ap- 
pearances common to viscous substances which have been in a fluid 
state. Above these layers, for example, in Flat creek, near Spraker's 
basin, where the whole series may be seen to the greatest advantage, 
there are thin layers containing the impressions of imperfect fucoides or 
marine plants, the only common fossil of this rock. These plants, in 
all probability, were the source of the coaly matter, the separation of 
the carbonaceous material having been effected by the action of thermal 
waters; the cause likewise of the product enumerated, as well as of 
other highly important phenomena, but which properly belong to sub- 
sequent rocks. Of the innumerable ancient localities where this sub- 
terrene action, as it may be called, has manifested itself, few only now 
exist in the United States, whose waters reach the surface. One in 
Buncombe county. North Carolina, another in Virginia, the third in the 
valley of the Hoosick, and the last in Arkansas. The first locality, 
from my observations, exists in a depression, by the side of which is the 
calciferous sand rock. Opposite to the springs of hot water, the layers 
of the rock are very irregular, more or less vertical, of a whitish colour, 
but at a little distance to the west, they present their blue colour, com- 
mon to this rock where lime is in excess and their well defined parallel 
lines of separation dipping to the east. The calciferous, with the pri- 
mary rocks to the east, form a synclinal line, a circumstance common 
to the hot springs of Virginia, as we find in the report of Prof. Rogers 
of that State, and no doubt common to the others likewise. 
