Coalfields of Pennsylvania and Nova Scotia. 67 
system rests upon a great development of sandstones and limestones, 
called by Prof. Rogers the Appalachian system, and divided by him 
into the following nine formations :— 
1. Red and buff-coloured shales and argillaceous sandstones, 
2, Olivaceous shales. 
3. Fossiliferous sandstones. 
4. Argillaceous limestone. 
5. Variegated calcareous shales. 
6. White and yellowish fucoidal sandstones. 
7. Red argillaceous shales, with soft and hard sandstones. 
8. Blue, drab and yellow shales. 
9, 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 eftect of these corrugations is stated 
to be remarkable. In the southern portion of the State, they have 
produced anticlinal hills and synclinal valleys ; but in the northern, 
anticlinal valleys and synclinal hills; while mid-way there is a de- 
bateable land, which sometimes presents one set of phanomena, 
sometimes the other. These different conditions, the author says, are 
assignable to the nature of the formations acted upon; thus, where 
the anticlinal lines constitute hills they consist of the hard quartzose 
conglomerate underlying the coal strata; but where they occur in 
valleys, they are always connected with the soft portions of the coal- 
measures or the softer red shales. 
The whole of the carboniferous regions above referred to, con- 
tain bituminous coal; but the detached districts on the Atlantic 
F2 
