W. M. Fontaine—“ Great Conglomerate” on New River. 575 
ell. These rocks of passage, as we may deem them, are suc- 
ceeded by the brilliantly colored red shales of the Subcarbon- 
iferous formation, which are greatly developed in this region. 
Rising from under them appears a great limestone formation, 
which is the base of the Subcarboniferous in Virginia, and 
which appears in great force around Lewisburg. While it is 
difficult to fix the eastern limit of the Conglomerate with exact- 
hess, owing to the blending of its base with the top of the enor- 
mously expanded Subcarboniferous formation, Rogers states 
that the following is the approximate boundary. In the north 
of the State, in Hampshire and Hardy Counties, it is in the east 
Front Ridge of the Alleghany; in Greenbrier and Monroe 
Counties, in the Greenbrier and Muddy Creek Mountains; and 
farther south, in the Great Flat Top Mountains.* 
In accordance with the above statements, we see that this 
lowest coal series on New River exhibits a triple structure, with 
asummit and base of conglomeritic sandstones, and a central 
portion of more argillaceous rocks, which contains beds of coal. 
If we compare this arrangement with that shown by the Con- 
glomerate in other portions of the country, we shall find that 
it is the typical arrangement of this formation, wherever it at- 
tains a considerable development. We shall also find that the 
thickening of the whole formation is mainly due to the expan- 
sion of the middle portion, and that the increase in the amount 
of coal closely follows such expansion. It may not be amiss to 
give a brief description of the Conglomerate at a few other 
points, in order to confirm these statements. 
At its northwest extremity, near Franklin, Pennsylvania, 
Prof. Rogers shows that the Conglomerate has nearly thinned 
out, and has no intervening argillaceous portion. The two 
bounding sandstones have come in contact. To the southeast, 
at Broad Top Mountain, it is, according to Lesley, less than 200 
ft., still containing the upper and lower arenaceous portions, but 
. how, in accordance with its increased thickness, containing a 
central argillaceous portion, with a small development of coal. 
Near Morgantown, at Laurel Hill, we have the triple arrange- 
ment, with an entire thickness, according to Dr. Stevenson, of 
about 350 ft. Near the center of the formation here, accordin 
to a local geologist, occur two beds of coal, the lower 165 in. an 
the upper 15 inches to 8 feet. : . 
The nature of the formation on New River we have already 
consider 
Followed to the northeast into the anthracite fields, we find a 
great expansion, with a corresponding development of the mid- 
* The details of general geology of the country, given in this paper to 
Shige te the aeeribonge the A caneionabas,” are eanly derived from Wm. B, 
Rogers's Virginia Reports. 
