31)2 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
against lateral secretion as a method of concentration. So far as 
seen, no gold occurs in whin, and the superjacent slate is reported 
to be barren by those who have tested it. Experience elsewhere 
shows that, when gold has come from the country-rock, its source 
has been chiefly slate. In this region the latter occupies scarcely 
one per cent of the section traversed by the veins; hence to have 
been leached of sufficient gold to give over an ounce per ton of 
quartz, as is yielded in some shafts, the rock must have been extra¬ 
ordinarily rich. There is no evidence whatever that this has been 
the case. On the other hand, the structure of the veins and the 
character and positions of the accompanying minerals point strongly 
to a deep-seated origin for the metal. 
JEruptives. —The only eruptives that have come under my notice 
belong to the granitic series. Their general distribution can be 
seen on any of the later geological maps of the Province. The 
edge of one boss lies a short distance east of Waverly, but it has not 
been possible to give it a careful examination. What has been 
seen confirms the general conclusions of the later writers. The 
rock alters already metamorphosed strata; yet Gilpin in ’82, and 
again in ’85, agreed with Dawson in claiming the rough contem¬ 
poraneity of the intrusion of the granites and the formation of the 
veins. In ’88, however, Gilpin implied the greater age of the latter, 
in stating that by the intrusions they are not “ changed from their 
normal character beyond any slight variation due to metamorphism 
of the small percentages of lime, etc., commonly occurring in them.” 
In Halifax another large mass of granite has its eastern bound¬ 
ary. The rock is a coarse liornblendic granitite, whose contact has 
not yet been studied closety. Near it the slate loses its fissile char¬ 
acter and largely its jointing, and becomes harder and more com¬ 
pact. Between the granite and this portion of the slate, where I 
have seen it, is a rock which in the field appears to be a rather 
coarse trap. Microscopical study of the problem has not been 
possible. The granite near this trap is fine-grained, and becomes 
steadily coarser for half a mile away from the contact. As it grows 
coarser a porphyritic structure appears, the ortlioclase crystals 
attaining a length of from one to one and a half inches. The rock 
as a whole is very feldspathic and weathers rapidly. This field 
west of Halifax is one which could be employed to great advantage 
in a study of the relations between the granites and the elastics. 
Denudation. — The structure of the series as a whole is not well 
