22 THE GKOLOGIST. 
for storing lumber. The rough blocks of grauite have fallen from the 
top of the entrance so as to form a rude arch, and imbedded in the rock 
forming the sides of the entrance are to be seen several large round 
Lign. 2. — Natural Cave on the Hugh — a, a, Rounded Boulders of Uraaite. 
boulders of granite, almost as regular as if they had been turned in 
a lathe, and compactly fixed in the matrix of the rock. Now this 
spot is considerably above the present level of the sea, probably from 
150 to 180 feet, and the boulders of granite bear all the marks of 
having been long rolled on a rough sea-beach. Moreover, I was 
assured by the masons to whom I referred above, that they had been 
engaged in repairing the guard-house floor; and on digging beneath it, 
they found other boulders, of precisely the same character as those at 
the sides of the cave, firmly imbedded in the soil. It is manifest, then, 
that the spot now adjoining the guard-house must once have been on 
a level with the surrounding sea, or, at any rate, at no great elevation 
above it, for glacial action alone would be, I conceive, scarcely suf- 
ficient to account for the presence of these rounded boulders, so deeply 
impacted in the solid rock. 
It becomes interesting, therefore, to inquire whether there are 
any traces of volcanic or subterranean action still visible in these 
islands, to which this upheaving of the land, after one or, it 
may have been, frequent submersions, may be attributed. And a 
careful investigation will bring to light several proofs of such 
volcanic or subten-anean force. In the direction of the causeway, 
I 
