TRANSACTIONS OF SECTIOX C. 659 



MOXDAY, AUGUST 23. 



The following Reports aud Papers were read ; — 



1. Report on the Erratic Blocks of the British Isles. 

 See Reports, p. 3-19. 



2. On the Relations and Structure of certain Granites and associated Arkoses 

 on Lake Temiscaming, Caiuida. By A. E. Barlow, M.A., and W. F. 

 Ferrier, B.A.Sc, Geological Survey of Canada. 



The rocks to which the following facts relate outcrop on both the eastern and 

 western shores of Lake Temiscaming immediately north of the ' Old Fort ' Narrows 

 on the upper Ottawa river, the deep channel of which forms the boundary line 

 between the Provinces of Ontario and Quebec. 



On the eastern side of the lake the granite forms a strip along the shore half a 

 mile wide, and extending from a point three-quarters of a mile north of The Narrows 

 on which is situated the now abandoned Fort Temiscaming, a fur-trading post be- 

 longing to the Hudson Bay Company, to the steamboat wharf near the village of 

 Bale des Peres. It also constitutes the rocky promontory known as Wine Point 

 to the west of Bale des Peres, extending inland in a north-easterly direction for 

 about one mile and a quarter. On the western side of the lake the first outcrop is 

 noticed about half a mile west of ' The Narrows,' continuing along the shore for 

 about four miles as far as Paradis Point, and varying in breadth from half a mile 

 to one mile. The whole area thus underlaid by the granite is approximately about 

 six square miles. 



Macroscopically the fresh rock is a rather coarse, though very uniformly even 

 grained aggi-egate of felspar, quartz, and a dark coloured mica, probably biotite. 

 Felspar is by far the most abundant constituent, and the abundance of red oxide 

 of iron disseminated through all the cracks and fissures of this mineral gives to 

 the rock its beautiful deep flesh-red colour. The quartz is, as usual, allotriomor- 

 phic, but a decided tendency is noticed to segregate in more or less rounded areas 

 or individuals which, especially on surfaces worn and polished as a result of glacial 

 action, gives to the rock a porphyritic or pseudo-conglomeratic appearance ; a fact 

 first made note of by Sir William Logan in 1844 on his manuscript map of this 

 portion of the Ottawa river. 



The microscope shows the rock to be composed essentially of orthoclase, micro- 

 cline, plagioclase (oligoclase ?), quartz, and biotite almost completely altered to 

 chlorite. The microline has evidently Ijeen derived from orthoclase as a result of 

 pressure, and all the gradations of this change may be noted, from the ' moire 

 structure ' characteristic of the imperfectly or only partially developed mineral, to 

 the fine and typical ' cross-hatched structure ' peculiar to this mineral. The fel- 

 spar shows only incipient alteration to sericite, and scales and flakes of this mineral 

 are developed especially abundantly in the central portion of the individuals, leaving 

 a comparatively fresh periphery almost altogether free from such decomposition 

 products. 



The arkose with which this granite is associated and surrounded is a beautiful 

 pale or sea-green quartzite or grit, passing occasionally into a conglomerate, the 

 pebbles of which are chiefly grey and red quartz with occasional intermixed frag- 

 ments of a halleflinta-like rock. 



Under the microscope the finer-grained matrix appears to be almost wholly 

 composed of pale yellowish-green sericite in the form of minute scales and flakes, 

 although occasional individuals are macroscopically apparent. Most of this sericite 

 has originated from the decomposition in situ of felspar originally present, and 

 irregular portions or areas of the unaltered felspar may be occasionally detected. 



The line of junction between this granite and arkose shows a gradual and dis- 



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