258 ROYAL SOCIETY OF CANADA 



It also is cut by a camptonite like dyke. It is composed of similar in- 

 trusive material to that of the other occurrences, but one noteworthy 

 feature is that although itself in the gneiss, it contains fragments of 

 Potsdam sandstone and one of a rock probably the Calciferous, both of 

 which are stratigraphically higher than the gneiss. 



Kear Ste. Anne de Bellevue. 



Sir William Logan describes this occurrence as follows : — " In one 

 of the cuttings for the Grand Trunk Eailway, between Pointe Claire and 

 Ste. Anne (west of Montreal), there occurs a strip of dolomitic conglo- 

 merate, filling a worn fissure in Trenton limestone. It is about a foot 

 in width and some ten or twelve feet in length, but none of it appears 

 on the surface of the limestone on either side." ^ 



A specimen from the Peter Eedpath Museum of McGill University 

 shows angular fragments of sandstone, hornstone and limestone, pheno- 

 crysts of pyroxene and bi otite, also several large spots of mixed pyrite 

 and ilmenite. The whole is cemented by a greenish coloured paste. The 

 fragments show alteration due to heat, — the sandstone has a quartzite 

 rim, the hornstone has apparently formerly been a shale, while the lime- 

 stone is changed to a crystalline marble. (See fig. 2.) 



A thin section shows pyroxene, olivine, pyrite, perovskite, epidote, 

 quartz and calcite. The pyroxene is augite, giving extinction angles up 

 to 43°, and occurring as remnants of large phenocrysts. Although com- 

 pletely decomposed, one phenocryst is recognized as olivine by its form 

 and characteristic filled partings. Pyrite is abundant, but very scattered. 

 Perovskite is plentiful as small octahedra. A subangular cavity (pos- 

 sibly an amygdule), is now filled with quartz, in freely formed crystals 

 surrounded by a layer of second deposition, then the remaining inter- 

 spaces filled with chalcedony. The epidote is secondary, occurring in 

 green coloured pleochroic crystals. 



Southwest End of Ile Bizaed. 



Near the southwest end of He Bizard there is an important occur- 

 rence of breccia which has not been previously described. ( See plate II. ) 



This occurrence forms a hillock about fifteen feet high, with 

 an area of fifty by one hundred paces in what would otherwise be a flat 

 locality. Attention is also drawn to the hill from the fact that it forms 

 a hu m mock on the highway, wliich happens to run over the highest part. 

 (See fig. 3.) The slopes are covered with fragments of the breccia, but 

 only a small amount is exposed which is positively in situ. The occur- 

 rence appears to be caused by a plug of breccia which has forced its way 



1 Geology of Canada, 1S63, p. 357. 



