223 
Geological Relations of the East of Ireland . 
each other, from a few inches to six and eight inches thick, 
composed of coarse grained conglomerate, greenstone, and finer 
grained conglomerate, all analogous in composition to those 
already described. We now encounter a conglomerate, composed 
of angular and rounded masses of greenstone, cemented by calca- 
reous spar ; and this is succeeded by slaty fine grained conglome- 
rate, into which it seems to pass. Limestone then appears, at first 
intermingled with greenstone and greywacke slate, and afterwards 
alternating with the latter rock. The range of the beds in this spot 
is north-east and south-west, and the dip 20° south-east. The inter- 
mixture of limestone with the greywacke slate is very distinct in the 
vertical section of the cliffy south of the martello tower ; where we 
perceive numerous boulders, pebbles, and masses of limestone scat- 
tered through the rock, frequently affecting a nearly rectilinear 
disposition across the strata, and nearly at right angles with the dip ; 
(see Plate 13. fig. 9.) 
In a similar cliff, adjoining on the south, this arrangement is still 
more striking, the limestone pebbles appearing in clustered masses 
of an irregular form, and occupying a space from a few inches to five 
and six feet wide, but also affecting a disposition at right angles 
with the dip of the greywacke slate; (see Plate 13. fig. 10.) 
In a cave, a little farther south, the limestone is seen in thin layers 
seldom exceeding four or five inches in thickness, repeatedly alter- 
nating with the greywacke slate* The range is here 10° west of 
north and east of south, and the dip 50° toward the east. Farther 
south, the alternating beds of limestone gradually acquire a greater 
thickness, but even here some of the beds consist of conglomerate, 
composed of large pebbles and angular fragments of limestone 
cemented by greywacke slate. Limestone now predominates in 
massy strata, some of which are several feet in thickness, ranging 
