384 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
veins. Horses are abundant, and in some cases the wall-rocks are 
brecciated for several inches and impregnated with minerals. The 
series lies, as far as my observation shows, within what may be 
regarded as essentially a single bed of whin. The latter is com¬ 
posed in reality of many heavily bedded strata interspersed with a 
few thin layers of slate carrying some veins of the bedded kind ; 
but the proportion of slate to whin is exceedingly small. On the 
south of this belt, which is one or two miles broad, 2,000 feet of 
slate overlie the gold-bearing rocks. On the north those who live 
in the district report another broad band of slate, with a small 
amount of whin. The cross-leads die out on the margin of the 
slate on the south, and have been looked for in vain on the north. 
If the fissures extended bevond the belt of whin, veins would be 
found in them. It seems, then, that here may be a case on a large 
scale of what the studies of Mr. J. B. Woodworth have shown to 
be common in a small way — a system of joints, confined to a 
series which is essentially homogeneous, and disappearing when 
rocks of different texture are reached. 
Cleavage has had no effect upon either the bedded or fissure-veins 
of the series. The quartz has been more or less crushed, but it is 
impossible to say that this was accomplished by the force which 
produced the parallel fissility. As a rule, cleavage has ignored the 
veins, stopping on one side and beginning again on the other; but 
occasionally it has swerved a little from a true plane. This happens 
where the side of a roll presents surfaces nearly parallel to the 
Diagrammatic section of quartz vein in slate, Moose River Mines. Vein, 
white; stratification, light full lines; cleavage, light dashed lines; joints, heavy 
full lines. 
