236 
Mr. Weaver on the 
same, whether exhibited in miniature or displayed on the great scale ; 
and here, within the compass of a few square feet may be learned 
some of those principles, which alone yield a safe conduct to the 
miner in his subterranean researches ; (§ 113.) 
In the coast, extending from the cove above mentioned, to 
Skerries, veins and seams of quartz appear almost exclusively in 
the stratified rocks, those of calcareous spar having ceased to occur. 
§ 129. The island of St. Patrick exhibits rocks of the same cha- 
racter as those of Skerries, composed of fine grained greywacke in 
alternation with greywacke slate and clay slate, in beds from half an 
inch to some feet in width, which preserve a due east and west rec- 
tilinear course throughout the island. The dip is uniformly toward 
the south, but the angle varies, approaching in the central part 
within 20° or 10° of the perpendicular, but to the southward ac- 
quiring the low angle of 30° with the horizon. In some of the 
slaty rocks may be observed thin layers of limestone from one-eighth 
to one-tenth of an inch in thickness, and also filamentous veins of 
the same substance. The western side of this island presents a good 
vertical and horizontal section of these rocks, in which the alter- 
nating beds are well marked by their difference of colour. They 
are sometimes waved on a very small scale, but the general direction 
remains nearly rectilinear. 
§ 130. The constitution of the islands of Count and Shenex is 
similar ; and as Rockabill islands lie nearly due east of these, it is 
highly probable that their structure is also the same. 
§ 131. The transition district, which we have now followed 
from the Delvan stream to the parallel of Skerries, forms a narrow 
ridge inland, being immediately Banked on the west and the south 
by the floetz limestone formation ; which appears also on the east, 
at low water, and covering the transition rocks at the point of 
