Geological Relations of the East of Ireland . 285 
§ 185. In the escarpment on the north-western side, above the 
limestone, we observe in succession, 
«. Shale. 
b . Gritstone. 
c. Shale, with subordinate beds of grit. 
^.Gritstone again, this last being the principal bed of sandstone, 
and, when not surmounted by superior beds, constituting the main 
body of the elevated part of the coal hills. It is the seat rock 
of the coal. 
This seat rock undulates repeatedly in a direction from the north- 
west toward the south-east, and could we divest it of the upper 
beds, we should perceive unequal ridges affecting in general a north- 
eastern and south-western direction, with intervening hollows, 
troughs, or basins, whose average breadth bears but a small propor- 
tion to their length. 
These hollows are occupied by beds, which succeed each other 
in the following order, beginning with the lowest ; 
a. Seat grit rock. 
b. Fire clay, resting on the seat rock, and forming the immediate 
floor of the coal. 
c. Coal. 
d. Roof shale, dr slatje clay, being the cover, with nodules of clay 
ironstone. 
e. Top grit rock. 
f. Top shale, at times with discontinuous layers of nodular clay 
ironstone. 
In some instances, this series appears to be repeated, two or more 
seams of coal lying in the same trough, one above another. 
