708 
of 50 fé: et, the whole resting upon a hard, coarse conglomerate, which 
is from 800 to 1200 feet thick at its south-eastern development, but 
is con siderably thinner to the north-west. Beneath the conglome- 
rate i's a deposit of red shale which varies in thickness from 3000 
to less than 100 feet, and disappears, it is believed, to the south- 
west. The next formation in descending order, with the exception 
of ari interposed bed of fossiliferous limestone, consists of massive 
sand stones, conglomerates and shales, and it possesses a more uni=- 
forn a thickness than the two next superior deposits. All these for- 
ma/cions are considered by Prof. Rogers to constitute a carboniferous 
system, though no profitable coal exists below the uppermost de- 
po sit; the remains of plants however occur throughout, and one or 
more seams of coal about a foot thick exist in the red shales. This 
sy stem rests upon a great development of sandstones and limestones, 
called by Prof. Rogers the Appalachian system, and divided by him 
rato the following nine formations :— 
. Red and buff-coloured shales and argillaceous sandstones, 
.. Olivaceous shales. 
. Fossiliferous sandstones. 
. Argillaceous limestone. 
. Variegated calcareous shales. 
. White and yellowish fucoidal sandstones. 
. Red argillaceous shales, with soft and hard sandstones. 
. Blue, drab and yellow shales. 
. Blue limestone. 
The aggregate thickness of these deposits is stated to be upwards 
of 20,000 feet, and the whole of the formations from the top: of 
the coal-measures downwards, to constitute one conformable series. 
The bottom limestone ( No. 9.) has a wide range, extending through 
New York to the banks of the St. Lawrence, and it is believed, on 
account of its fossil contents, to belong to the lower Silurian series. 
The entire 13 formations constitute a gigantic trough, the axis of 
which strikes from N.E. to S.W.; and along the N.E. outcrop of the 
carboniferous measures it has several deep indentations, occasioned, 
according to the observations of the State Surveyors, by a series of 
remarkable curvilinear, anticlinal axes, distant 10 or 12 miles from 
each other, and which preserve not only a parallelism among them- 
selves, but, with the Alleghany and Appalachian mountains, increa- 
sing also in sharpness and importance as they approach these chains. 
The north-western anticlinal is the least conspicuous, but its'effect 
on the margin of the coal-field is very perceptible; the 2nd has been 
traced 125 miles from the northern boundary of the State; the 3rd 
160, the 4th 200, each penetrating to a greater extent within the 
coal area, and then flattening down; the 5th and 6th have been as- 
certained to have a range of 250 miles from the county of Susque- 
hanna, and to traverse the whole of the coal district to the southern 
boundary of the State; but the 7th has been traced only 60 miles, 
or from the confines of Pennsylvania with Virginia to the Alleghany 
mountains, one of the ridges of which is considered to be a con- 
tinuation of it. The different effect of these corrugations is stated 
4 
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