185 
Geological Relations of the East of Ireland. 
less intermingled with quartz rock. Smaller masses of quartz oc- 
cur also farther north under similar circumstances, as in the defiles 
leading toward Newtown Mount Kennedy, and again close to 
Kilcool, on the north side of that village. 
§ 78. But no portion of the tract presents better opportunities 
for examining the relations of quartz rock and clay slate, than that 
which extends from the north-eastern arm of Djouce mountain 
eastward to the coast ; (see Plate 8. No. 8.) On the east it is 
bared by the sea ; on the west it is furrowed by deep ravines, 
which range to the north between Long hill and the western foot 
of Great Sugar Loaf ; and on the north it is broken through by 
the course of the Dargle river. On the south side of this stream 
we observe three great protruding masses, the two Sugar Loaves 
and Bray Head ; and to the north the smaller one of Shank hill ; 
all principally composed of quartz rock. They stand like monu- 
ments that have in a great degree withstood the abrading power of 
the elements, while their more decomposable associate clay slate, 
has given way. To avoid tedious repetition, I shall here present a 
brief summary of the mutual relations of these two kinds of rock, 
both in respect to composition and association, as they appear in 
this vicinity. 
§ 79. Quartz Rock. Its characteristic colour is white, usu- 
ally light yellowish or greyish white ; but sometimes it is more or 
less deeply stained yellow, red, and brown. Its exterior is often 
of a glazed brilliant white, as if a solution and re-consolidation of 
the surface had taken place. In its structure it varies from the 
perfectly compact splintery to the close grained granular ; some- 
times containing small well-defined rounded grains of quartz, which 
are frequently of a different colour from that of the base, even pale 
pink or purplish ; as, for example, in the peaks of the two Sugar 
Vol. V. 2 a 
