the main mass of the ledge, is of the 
coarse, irregular type seen in Crescent 
Hill and on the east shore of the bay, 
containing many large pebbles of gran- 
ite, felsite and melaphyr. The breadth 
of the conglomerate outcrop, from 
northwest to southeast, is about 140 
feet; and the thickness of the bed, the 
upper and lower surfaces of which are 
clearly exposed, is about 25 or 30 feet. 
It is underlain on the northwest, at the 
very base of the ledge, by a highly 
scoriaceous and amygdaloidal green 
melaphyr, of which only a slight thick- 
hess is exposed ; and is overlain on the 
southeast by a very similar flow of 
melaphyr, which at one point reaches 
up over the conglomerate nearly to the 
top of the ledge. These are undoubt- 
edly true effusive contacts, and the up- 
per one especially shows the dip of the 
conglomerate to be S. E. 10°—20°. 
The melaphyr contains abundant seg- 
regations nd veins of epidote and red 
Jasper. Since there appears to be no 
reason whatever to question the strati- 
graphic equivalence of Crescent Hill 
and Marsh Island, it is necessary to 
suppose that the marsh between them 
conceals an important fault ; the down- 
throw being to the north and fully 
equal to the combined thickness of the 
conglomerate and upper melaphyr, 
about 50 or 60 feet. 
The foregoing details, which are summarized 
south section (Fig. 
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