2 1 S On the Geology of the Island of Montreal. 



that all rocks, on the application of strong heat, as on expo- 

 sure to the cooking fire of a Canadian voyageur, including 

 trap, and its conglomerates amygdaloid, granite, gneiss, quartz 

 rock, he. he. shale superficially, w slaty, lenticular, and often 

 large fragments, without attention to natural cleavages. I 

 do not intend to make any deductions from this fact at pre- 

 sent. These calcareous nodules are frequeut at the east end 

 of the Lachine Canal, with the gravelly earth spoken of 

 above ; but in a mile or so west, on its route, (the exact dis- 

 tance my notes do not give) it is succeeded by a deep blue 

 viscous clay, containing among other pebbles, small masses of 

 the black limestone without shells. This blue clay (still con- 

 tinuing along the canal) is succeeded, at two and a half miles 

 from Montreal, by a bed, cut through for one hundred yards, 

 of very soft and flaky white marl, full of fresh water shells. 

 It is covered for three feet by decayed vegetables, and has 

 itself been penetrated for the same distance without reaching 

 its under surface. This bed has limestone, in situ, close on 

 its west. Its shells are in great numbers, and precisely those 

 inhabiting the contiguous waters and great lakes. They are 

 decomposed ; that is, are soft, brittle, and white, but not at all 

 impregnated with carbon, flint, or calcareous matters. Plan- 

 orbis bicarinatus, deflectus, and trivdvis, Melania virginica, 

 and Phijsa heterostropha, are about in equal quantities. 

 The Unto is rare, and always in fragments. I met with a very 

 delicate and small Lymnaus elongatus, similar, except in size* 

 to the living shell in the Little La Croix river, leading to 

 Lake Vermilion, on the north and west of Lake Superior. 

 Lymnaus emarginatus, Valvata sincera, and Cyclas similis, are 

 also present. There are some pits on the north of Montreal 

 Hill, from whence Dr. Lyons has brought fresh water shells, 

 of the genus Saxicava, which I have found likewise in a 

 streamlet on the Ottawa, one hundred and twenty miles west 

 north west of Montreal, and five miles into the woods from 



