241 
Geological Relations of the East of Ireland, 
quarters. On the north side, they usually range north-north east 
and south-south west, dipping south-south east ; in this part, how- 
ever, they seem in some cases to dip on the declivity north-north 
west ; but this is probably no more than a superficial inflection. 
In the western portion of the tract, in the vicinity of Lackamore 
mine, the range is north-east and south-west, and the dip south- 
east ; but in a cross-cut driven from the mine to the north-west, 
the rock near the forebreast dips to the north-west. In the outlet 
of the Bilboa river on the south, the structure and succession of the 
rocks may be distinctly traced, the river being there confined to a 
narrow rocky channel, leaving lofty banks and brows on either side, 
near one hundred feet in height. Below the fork of the river the 
clay slate, which alternates with beds of the character of greywacke, 
supports sandstone conglomerate of a coarse structure in a con- 
formable position, dipping at an angle of 20° to the north of west. 
The latter rock consists of a base of quartzy sandstone, enveloping 
numerous fragments of clay slate and quartz, of various size, and 
both rounded and angular, some of them exceeding the head in 
magnitude. But the upper strata of this conglomerate pass gradu- 
ally into a fine sandstone, consisting of a minute granular aggrega- 
tion of quartz, with scales of mica, and interstices filled with yel- 
low iron ochre. From the fork of the river to the mouth of the 
defile, where the Bilboa discharges itself into the plain, is about 
three quarters of a mile. The sandstone disappears about one 
quarter of a mile below the fork under alluvial soil, the banks of 
which are here from 60 to 70 feet high. Frcm the mouth of the 
defile to Castleguard is about one mile, and at this place floetz lime- 
stone crops out in massy strata, very close to the Bilboa river, dip- 
ping toward the same quarter as the sandstone, at first under an 
angle of 20° and subsequently of 10°. 
That portion of the sandstone, which extends between Lacka^ 
Vol. V. c 2 H 
