Chap. XIX.] 
GOLD OF SOUTH AMEEICA. 
469 
(in great part, at least) of Palaeozoic age. That a large portion of the northern- 
most Rocky Mountains, both British and lately Russian, will prove to be auri- 
ferous is indeed to be inferred by the discoveries in British Columbia. 
Rocks of Lower Silurian age in] Nova Scotia have already yielded a notable 
quantity of gold. It is in the veins traversing the slates and quartzites, and 
usually coinciding with the strike of the containing beds, just as in Australia. 
The manner in which these veins conform to the flexures of the beds, as in the 
curious deposits known as ' barrel-quartz,' indicates that they are of the nature 
of segregative veins, and cotemporaneous with the disturbance of the beds. 
This view is corroborated by the occurrence of rolled pieces of the auriferous 
quartz in the Lower Carboniferous conglomerate (Hartt), while the alteration 
and disturbance of the auriferous rocks themselves are connected with outbursts 
of granite. The gold of Nova Scotia is associated with mispickel, copper-pyrites, 
galena, and blende. Some of the mines have penetrated to a depth of 220 feet, 
and are very productive, though their capabilities are by no means perfectly 
tested. The yield of gold in 1865 was 24,867 ounces, according to the Report 
of the Commissioner of Mines. 
Recent discoveries in South America and California have led me to modify, 
to a certain extent, as before said, my previous opinion concerning the rocks con- 
taining gold. Yet, after the explanation I am about to give, it will be perceived 
that the newer data do not essentially interfere with the general conclusion at 
. which I formerly arrived. In the year 1860, Mr. David Forbes pointed out that 
eruptive masses of auriferous diorites and greenstones (rocks composed of felspar 
with hornblende, but devoid of quartz as a normal constituent) had caused the 
introduction of metalliferous veins or lodes containing gold * into the neigh- 
bouring strata of Secondary age, and, to a small extent, impregnated with gold 
the beds through which they had penetrated — strata which in their normal 
state were entirely devoid of gold f . Extending his observations in subsequent 
years, the same intelligent and persevering explorer showed, by observations in 
Chili, Peru, and Bolivia, that gold had made its appearance in the crust of the 
earth at two distinct periods, and in both through igneous agency The oldest 
he referred to the protrusion of granite amongst the ancient deposits, the younger 
to the eruptions of diorite or greenstone, which he found had been intruded 
into and affected rocks of the younger Oolitic period §. To whatever extent this 
view may be found to accord with observations in other parts of the world, I 
may here remark that, as regards this comparatively recent appearance of gold 
(geologically speaking), the observation of Mr. Forbes is quite in accordance with 
the phenomena recorded by myself and my companions in describing the struc- 
ture of the Ural Mountains ||. In that region, as already stated, we had the 
clearest evidence that the Silurian and other Palaeozoic formations of the chain, 
up to the Carboniferous inclusive, had not been impregnated with gold, as* already 
stated, when the Permian conglomerates and sandstones (which had been derived 
exclusively from all the Palaeozoic, metamorphic, and igneous rocks of those moun- 
tains) were accumulated ; for, although abundantly charged with iron and copper- 
ores, these Permian deposits afforded no detritus of gold throughout a length of 
* Darwin, in his geological observations on t Quarterly J ournal of the Geological Society, 
South America, 1846, p. 236, mentions incidentally vol. xvii. p. 31 &c. 
that in Chili gold and copper-ore are found to- J Eeport of British Association, 1865, Trans, of 
gether in the porphyry-conglomerates at Quillota Sections, p. 52. 
and Jajuel, and at the latter place also in green- § In a communication to the ' Geological Maga- 
stone, and further remarks that a similar occur- zine,' vol. iii. Sept. 1866, Mr. Forbes expresses his 
rence of gold in copper-ores is seen at Los Homos, belief in the general application of these views to 
north-east of Illapel, and in the Uspallata range all parts of the world. 
in metamorphosed strata, probably later than the || See ' Eussia-in-Europe and the Ural Moun- 
gypseous or Neocomian formation. tains,' vol. i. p. 475. 
