Guide books of excursions in Canada1-10 . in the direction of the movement of itsflow, as shown by their relation to the direction of itsfoliation. These are clearly fragments of the limestonecover of the batholith which have been folded, or havefallen down, into the magma of the invading batholith. The nepheline syenite shows a distinct banding andfoliation, conforming in strike to the foliation of thegneissic-granite, as well as to the bedding of the limestoneseries. At Bancroft this nephleine syenite is nearly a mile(i -6 km.) in width measured across the strike of the foli-ation, the dip b
Guide books of excursions in Canada1-10 . in the direction of the movement of itsflow, as shown by their relation to the direction of itsfoliation. These are clearly fragments of the limestonecover of the batholith which have been folded, or havefallen down, into the magma of the invading batholith. The nepheline syenite shows a distinct banding andfoliation, conforming in strike to the foliation of thegneissic-granite, as well as to the bedding of the limestoneseries. At Bancroft this nephleine syenite is nearly a mile(i -6 km.) in width measured across the strike of the foli-ation, the dip being to the south. East of the village itincreases i .pidly in volume, attaining its maximum devel-opment in the vicinity of Bronson post office, whereextended and often almost continuous outcrops may befound for over two and a half miles (4 km.) in a north andsouth direction. In this, which may be termed theBancroft district, the nepheline and associated alkalinesyenites cover an area of about 15 square miles (37 sq. km.). Excursion Bancroft and Vicinity 49 These syenites show a marked variation in the relativeproportion of the principal mineral constituents. Indeedextreme and rapid variation in composition is one of themost noteworthy features of their development, so thatit is possible to obtain from the same exposure, and evenfrom contiguous bands, different and quite distinct typesof rock. Some varieties are abnormally rich in nepheline,while others contain a much smaller proportion of thismineral, passing by insensible gradation into alkaline-syenites, composed almost wholly of feldspar. Certaintypes are relatively rich in ferromagnesian constituents,which may be either mica or hornblende, while otherphases of these rocks contain very little, if any, of thesecoloured minerals. Some exposures are characterized bythe interesting alkali-hornblende to which the namehastingsite has been given, while in some localities garnetis present in considerable amount. The actual re
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectgeology, bookyear1913
