FOSSIL COAL PLANTS. 7 | 
consequently is very expensive to operate in; as all know, to their cost, who have had to 
pass through it, by drifts or shafts. 
The direction or level course of this vein, in the gangway, is from 19° to 25° to the 
northward of east; that is to say, commencing in a course north 64 east, it Sweeps round 
to north 71° east. It will be sufficient for our purpose, when speaking of bearings, to 
limit our description simply to the cardinal points. 
Between the north and south walls the interval is eight or nine feet: of which space 
five and a half feet consist of coal, divided in the midst by a seam, two or three feet 
thick, of fire clay. Along the course, therefore, of this coal seam, and bounded by its 
walls, the exploratory gallery has been pursued. With so high an inclination as seventy 
degrees, these walls are not unsuitably disposed for the purposes of the mine; and are 
especially adapted to the display of the vegetable fossils, which appear like pictures sus- 
pended from a wall, on either hand. 
I have said thus much in explanation of local details, because, without them, our posi- 
tion could not be understood. 
It has been stated that all the principal coal seams, known to me in this vicinity, have 
floors of argillaceous matter, called the “bottom slate,’ and roofs of conglomerate rock 
In the present instance these lower slates, comprising two thin seams of coal and some 
thin beds of argillaceous sandstone, are seventeen feet thick, before reaching the next 
conglomerate, on that side. ‘Turning to the north, the bare wall of conglomerate forms 
the hanging side of the coal seam, without any separating matter between it and the coal, 
except from two to four inches of shale, called by the miners the “top slate.” This is 
commonly stripped down in the process of excavating the coal; as the slate here parts 
more readily from the rock, than the coal separates from the slate: moreover the solid 
rock forms a safer wall than does the loose shale. Occasionally, as in other veins we 
have traced, the conglomerate even comes in contact with the coal itself; exhibiting the 
form of the coal vegetation upon its under surface; and, notwithstanding the coarseness 
of the materials of this rock, may be often seen moulded into the configuration of the 
larger plants, which even retain their carbonized bark. 
The irregular space between the actual serviceable coal and its overlying pudding- 
stone, is almost entirely occupied with casts of trunks of trees, lying horizontally; that 
is to say, parallel with the coal. 
These preliminary explanations will, I think, render the position of an observer in this 
gallery, sufficiently intelligible. As he advances forward, towards the east, he has the 
clay floor of the coal seam, on his right hand, sloping at a high angle towards the north; 
while on his left, facing the north, the conglomerate roof, or hanging wall, approaches 
Within twenty degrees of the perpendicular. As in every case within my knowledge, 
the upper surface of the coal and the inferior surface of the overlying rock, are somewhat 
rough and irregular, forming a remarkable contrast to the lower surface of the same coal, 
and to the smooth and almost polished face of the subjacent slate. When the circum- 
stances which attended the slow and tranquil accumulation of the one, and the turbulent 
and disturbed condition of all things at the commencement of the other, are taken into 
consideration, we shall obtain a ready explanation of the irregular surfaces of all coa! 
seams which have conglomerate roofs. 
VOL. IX.—-59 
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