228 
Mr. Weaver on the 
mately into clay slate. The clay slate conglomerate constitutes a 
bed at least 200 fathoms in thickness, ranging 20° north of west and 
south of east, and dipping 65? toward the west of south. In its 
line of apposition to the compact greenstone on the north, it occu- 
pies only a small part of the northern side of Seal-hole Bay, but it 
also lines the bay itself, and extends to its south-eastern angle. 
This bay seems in fact to owe its form to the inroad of the ocean 
upon the great bed of conglomerate, the materials of which it is 
composed being loosened and disjoined by the action of the sea and 
the atmosphere. At the bottom of the bay a cavern has been form- 
ed, about thirty yards in length, which is frequented by seals, of 
which three or four have been taken there at a time. The conglo- 
merate there forms high impending cliffs ; and in its structure it is 
analogous to the clay slate conglomerate which rests upon the 
massy greenstone to the east of Portrane quay : a base of clay slate 
enveloping rounded and angular pieces of limestone, compact 
greenstone, fine grained greywacke, and greywacke slate, with 
Isome quartz, and calcareous spar being also more or less diffused 
through the mass. Some of the rounded and angular fragments 
exceed twice or thrice the size of the head. In the limestone frag- 
ments, organic remains, as bivalves, and also some entrochites, may 
frequently be observed. 
The clay slate conglomerate is succeeded to the south-west by 
massy compact greenstone with little, or no distinct, appearance 
of a subdivision into strata; and this rock constitutes the preci- 
pices along the south-eastern angle of the island, until we enter a' 
deep bay on the southern side, which is to the east of Talbot bay. 
Here may be observed two beds of clay slate imbedded in the 
massy greenstone, one in the eastern, the other in the western 
quarter; but neither of great dimensions, The range and dip 
