4 8 



clase has a tendency to assume a lath-like 

 development. The rock also contains a con- 

 siderable amount of scapolite as an accessory 

 constituent. A small quantity of a black iron 

 ore in rude, more or less rod-like forms, and a 

 few grains of pyrite are also present. The rock 

 is very fresh. 



After having inspected these quarries the 

 party will return to the train and continue the 

 journey to Bancroft. 



Geology in the Vicinity of Bancroft. 



The Grenville series, which with its associated intru- 

 sive masses of diorite and gabbro is traversed by the 

 Hastings road in a direction almost at right angles to the 

 strike of these rocks, furnishes abundant evidence of pro- 

 gressive metamorphism. At Bancroft, however, the con- 

 tinuity of this important series of very ancient crystalline 

 sedimentaries is interrupted by the intrusion of the great 

 northern granite batholith, flanked to the south by a wide 

 border of nepheline and other alkaline syenites. Small 

 and isolated inclusions of the Grenville series occur scat- 

 tered through the batholith to the north, linearly arranged 

 when they occur in the direction of the movement of its 

 flow, as shown by their relation to the direction of its 

 foliation. These are clearly fragments of the limestone 

 cover of the batholith which have been folded, or have 

 fallen down, into the magma of the invading batholith. 



The nepheline syenite shows a distinct banding and 

 foliation, conforming in strike to the foliation of the 

 gneissic-granite, as well as to the bedding of the limestone 

 series. 



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 it 

 increases i .pidly in volume, attaining its maximum devel- 

 opment in the vicinity of Bronson post office, where 

 extended and often almost continuous outcrops may be 

 found for over two and a half miles (4 km.) in a north and 

 south direction. In this, which may be termed the 

 Bancroft district, the nepheline and associated alkaline 

 syenites cover an area of about 15 square miles (37 sq. km.). 



