On the Geology of the Island of Montreal. 217 



mettes, Tamatsaming, Stc. are placed. Up the St. Law- 

 rence, and on its lakes, it is universal ; but broken even into 

 seven successive terraces, which is the greatest number I have 

 seen. It is continuous, downwards, from Montreal towards 

 the Atlantic Ocean, in one or more of these platforms, for 

 three hundred and fifty miles to my own knowledge, and 

 most probably, the whole distance of five hundred and eighty 

 miles j frequently, however, interrupted by districts of rock, 

 as I need scarcely add. 



This alluvial deposite, in the immediate vicinity of Montreal, 

 including the ridge and the marshy flat at its base, is com- 

 posed of different ingredients in different places. On the 

 banks of the river, and in the rear of the town, it is, at all 

 levels, a coarse mixture of ferruginous sand, reddish clay, 

 and gravel ; full of large bowlders of primitive rocks,* and 

 particularly abounding in large nodules of rusted black and 

 brown limestone. Here and there, without regularity, there 

 are very thin and partial beds of pure sand and gravel, in a 

 horizontal position. The former, however, I have learnt, 

 exists, as a very large and deep accumulation, at the east end 

 of the canal, close by, unfortunately for its cheap and per- 

 manent construction. The masses of limestone found among 

 these rolled substances, are always without shells : a remark- 

 able circumstance in a district of conchiferous limestone. It 

 is very shaly, but still not only weathers in its ordinary direc- 

 tion, but in concentric spherical layers, like the coats of an 

 onion, a mode of division not to be discovered in sound rock 

 of this nature ; but I have observed, upon an extensive scale, 



* Among the rolled masses of the fields and river banks, I have met with 

 pale green coccolite in tabular spar, with yellow mica ; dark green cocco- 

 lite ; fine granular, forming one third of a compound ; together with black 

 mica, and pink rhomboidal calcspar; a bowlder of tabular spar, white, and 

 unmixed, weighing six hundred pounds. Dr. Lyons has met with well- 

 marked rolled Labrador feldspar in the island of St. Helen, opposite the 

 town of Montreal. 



30 



