On the Geology of the Island of Montreal. 213 



dark variety predominates and runs into shale ; but of what 

 kind I have not yet ascertained. This rock occurs near St. 

 Henry's, and seems to be supported by the porphyritic trap 

 with the handsome druses of calcspar and epidote. The island 

 of St. Helen, which bears about north north east from the 

 place where this quartz rock occurs, is based on a modification 

 of greywacke, an extremely compact and hard conglomerate 

 of granular quartz masses, both angular and rounded, green, 

 gray, brown and black ; and varying in size from two inches 

 in diameter to microscopic. The cement is green, and in 

 sparing quantity. It contains, disseminated, iron pyrites, and 

 some copper-coloured mica, the latter being plentiful in some 

 of the fragments. I observed in it, one mass of colourless feld- 

 spar. This rock shows itself in a naked bluff, a few feet above 

 the St. Lawrence, on the north east of the Barracks of the Artil- 

 lery. I am informed, that it is either massive or divided into 

 very thick strata. 



I may place here the facts which have come to my know- 

 ledge respecting thp sandstone of St. Anne. It presents itself 

 on the shore of Lake St. Louis for two miles below that vil- 

 lage, and at the rapids of the same name, on the north east of 

 Isle Perrault, in thick horizontal slabs of light brown quartzy 

 sandstone, with ferruginous clouds and spots. It is hard, 

 fine-grained for the most part, and seems to have little or no 

 cement. It appears in large quantity at the Cascades, on the 

 opposite side of this body of water ; but as far as I am aware, 

 it is not seen in ascending the St. Lawrence, until we reach 

 the neighbourhood of St. Regis, (fifty miles south west) as we 

 learn from a printed report of Mr. Raymond, a surveyor, who 

 found it underlying much of the St. Lawrence county, in the 

 State of New-York. I have seen it, in the Thousand Islands, 

 resting on gneiss, directly and unconformably. From these 

 and other circumstances, I deduce a probability, that the 

 sandstone of St. Anne is below the limestone of Montreal 

 Island — a rock whose organic remains and accidental minerals 



