352 FOSSIL PLANTS. 
stances. But to omit theoretical discussion and merely consider 
facts observable around us, it is evident that our silicified wood;as 
well in our Coal Measures as in the more recent formations, is a 
found in connection with strata which show no trace of volcanic a 
agency. The silicified trunks of Southern Ohio have been washed F: 
out by the creeks from the Mahoning sandstone. The area cov- 3 
ered by this formation, and over which the trunks are found in 4 
greater or smaller quantity, extends from Athens southward, to | 
the Ohio river, and in Virginia, as far up the great Kenawha river E 
as Charleston, or about one hundred miles in a direct line. 
There is no trace of any volcanic agency in that country. No — 
disturbance of any kind is observable in the strata, which have — 
their normal, slightly marked dip to the eastward; nor does the E 
sandstone itself indicate, in its appearance, by a variation of its a 
compounds or of its density, any trace of metamorphism. At — 
Gallipolis, near the mouth of the great Kenawha, a number of a 
fossilized trunks, still buried in the sandstone, are seen protruding 
from the bank, in which they have been petrified in a prostra a 
position. As these trees have been examined already by other- 
geologists, and mentioned as indicating a peculiar direction of the | 
current, by which they have been brought and deposited, a short 
account of them here may not be uninteresting. ‘There are five of 
them, from four to fifteen inches in diameter, their length unknown, 
lying, two in a southeastern direction, one due east, and the two 
others due south. The part seen out of the sandstone is much 
decayed, the outer surface, where it is preserved, is covered by 
coat of coal varying in thickness from one-half to one-fourth of 
an inch. What is most remarkable, and bears directly on the 
texture has been destroyed, and the woody tissue is replaced 
by a hard calcareous sandstone or clay, separating in layers of 
about one-fourth of an inch in thickness. A second is a com- 
pound of small crystals of iron flint, its interior being perforatet 
lengthwise by a number of irregularly [placed cylindrical aper- 
tures, filled with small iron crystals, forming regular stars of 
more than twenty rays. A third, of which I have obtained large 
pieces, it being of smaller size, four inches in diameter, is trans- 
formed into a compact, opaque, black silex, which does not pte 
