24 The American Geologist, July, 1897 
diorite. The floor of the quarry is in marble — a sharp demarca- 
tion here taking place between the development of ore and the 
parent marble. The ore mass together witW a bleached over - 
lying greenstone forms half an areh over a boss-like mass of dio- 
rite — the crown of the arch being obliquely cut b^'' the superin- 
cumbent mass of basic diorite along a distinct plane of frac- 
ture and dislocation. Viewed in section coincident with the 
strike of the limestone, this ore-body may be considered as 
presenting the edge of a lenticular replacement of limestone, 
shelved or lapped in unaltered material, and of very circum- 
scribed extent. The upper portion only remains unwrought. 
The dip of the series brings in above the limestone a cover of 
diorite toward the verge of tlie quarry shelf. On the edge of 
the replacement proper — the dioritic greenstone has been al- 
tered into an epidotic magnetite by residual concentration of 
this product. The front of the ore-body has suffered from 
erosion which served however to disclose its upper part to view 
in an almost perpendicular cliff, whence the mountain rises 
very abruptly, thus forbidding further ready exploration along 
the culmination of the same belt. 
The East mine, some 60 feet higher, presents the simple 
structure of an eroded boss of magnetite arching over an in- 
terior mass of marble, the connected boss being cut off at the 
base by epidotic diorite, and the whole structure truncated in 
front by erosion, and so exhibited in the scarp of an almost 
perpendicular cliff on the precipitous face of the mountain. 
The structure referred tro may be likened to an egg obliquely 
divided. (Plate II, fig. 4.) 
Outcrops of ore in association with marble are observed 
below, but have not been prospected. The conditions above 
remain undetermined for want of exploration. Both occur- 
rences, as above described are developments of ore within and 
around disrupted masses of limestone involved in basic erup- 
tive material, though appertaining to a distinct belt which 
has been subjected to violent disturbance and upheaval. 
The occurrence of such ore bodies on West Redonda island 
is not without significance as bearing upon the possibility of 
similar occurrences on the steep shores of navigable inlets 
heading in the unexplored border of the Coast range. 
Vancouver Island,, Barclay Sound. — Discoveries of magnetic 
