212 On the Geology of the Island of Montreal. 



observed it there was a tendency to tbe granular form. Some 

 of it is shaly. The difference in level must be very small. 



The calcareous rock, which has been cut through in form- 

 ing the canal between Montreal and Lachine, is only seen in 

 the three and a half or four miles nearest the west end. It is 

 about on the same plane with the St. Lawrence. The ragged 

 edges of the upper and northern strata, above described, are 

 concealed by the large alluvial bank girding the hill. The 

 limestone of this locality varies in its external appearance. 

 In the eastern part of the above distance, it is pale, gritty, and 

 deficient in shells. I suspect the presence of quartz, but an 

 accident has deprived me of the opportunity of testing it. 



Proceeding westward, the limestone becomes bluish black, 

 and softer; a pale brown granular variety then intermixing with 

 it, by a sort of alternation ; both containing large druses of 

 very splendid crystals of dog-tooth, nail-head, lenticular, and 

 curved rhomboidal calcspar. Their organic remains are the 

 same. These pale and dark layers are in firm union, by a 

 wavy, but still horizontal line, the black one being usually on 

 the surface, and often azoophytic, while the inner brown parts 

 are full of shells, and approach to the crystalline state. The 

 limestone at the west end of the canal is all dark and shaly, 

 but is unchanged in other respects. Very fine fibrous arrago- 

 nite has been brought from hence, but I suspect from the trap. 

 It is in veins an inch thick, consisting of two closely connected 

 tables of equal size, one of which is white, with some degree of 

 translucency : the other is hyaline, and almost transparent. 



These limestones cannot now be examined, in situ, as they 

 are covered by the water of the canal, and by the earth forming 

 its sides ; but the fragments lying around, may be sufficient 

 for obtaining a pretty correct idea of their nature. These 

 materials also indicate, that in certain parts at least, it here 

 rests upon an indurated quartz rock, of very fine grain, black 

 and brown in alternate stripes, (the former shade being derived 

 from carbon) and sprinkled with dots of iron pyrites. The 



