28 T. STERRY HUNT ON THE _ GENETIC 
apple-green or grass-green in color, and then sometimes holds clove-brown titanite, brown 
tourmaline, and, more rarely, zircon. 
§ 49. These rocks, essentially made up of feldspar, quartz, and pyroxene, were long 
since noticed by the writer as occurring among the Laurentian gneisses in the Rideau 
district, and at various points in the province of Quebec, and were described in 1866 as 
generally “ granitoid or gneissoid in structure, sometimes fine-grained, and at other times 
made up of crystalline elements from two tenths to five tenths of an inch in diameter. . . . 
They are often interstratified with beds of granitoid orthoclase gneiss, into which the 
quartzo-feldspathic pyroxenites pass by a gradual disappearance of the pyroxene.” The 
occasional presence in them not only of titanite, but of mica, amphibole, epidote, magnetite, 
and graphite, was then noticed, and attention was called to the fact that these mineral 
species are common to the pyroxene rocks and to associated crystalline limestones. 
The feldspar of these intermediate rocks was described as having generally the characters 
of orthoclase, as was shown by the analysis of a specimen from Chatham, Quebec, but as, 
in some cases, triclinic and resembling oligoclase.' Dr. Harrington has since found for 
one of these the composition of albite. 
As will appear from the language just cited, these aggregates were then regarded as 
portions of the country-rock. The pyroxenite seen in North Burgess, in the Rideau 
district, was described as sometimes granitoid, and at other times micaceous and schistose, 
interstratified with what was then called a binary granitoid gneiss, and also with layers 
of crystalline limestone, some of them holding serpentine, and others including pyroxene, 
mica, and crystals of apatite. Both varieties of the pyroxenic rock were then said to 
contain small grains and masses of apatite, in one case forming an interrupted bed, which 
was traced two hundred and fifty feet with the strike, and was in parts two feet in thick- 
ness. 
§ 50. While apatite was thus found in crystals, in lenticular masses, and in layers, 
alike in the calcareous and the pyroxenic stratiform rocks, these same rocks were described 
as traversed at right angles by veins, the banded and symmetrical character of which was 
insisted upon, carrying not only apatite but calcite, quartz, orthoclase, scapolite, pyroxene, 
amphibole, and wollastonite. While the venous character of these secondary deposits 
(which also intersect the red and gray gneissic country-rock) was thus recognized, it was 
not until a later period that it became apparent that the same view was to be extended 
to the greater stratiform masses in which these veins were enclosed; in fact that the 
process of depositing these mineral species had been repeated in these localities, and that 
the pyroxenic and granitic rocks, not less than the interstratified limestone masses, were 
portions of great endogenous masses or lodes.” 
§ 51. At this stage of the inquiry the writer found himself face to face with the 
exoplutonists. Emmons, who, in 1842, first described the geological characters of the 
similar crystalline rocks in northern New York, regarded the whole of them—gneisses, 
granites, iron-ores, and crystalline limestones included — as of plutonic origin, a view 
which was supported by the evident geognostic relations of the calcareous veins. This 
was in accordance with the views of Von Leonhard, Savi, and others in Europe, who 

1 Geology of Canada, 1863, p. 475 ; also Report Geol. Survey of Canada, 1863-66, pp. 185 and 224-228. 
*¥For an analysis of the argument, and many references, see Amer. Jour. Science, 1872, iii. 125, and Chem. 
and Geol. Essays, p. 208. 
