MINERALS AND GEOLOGY OF CANADA. 9 



(Part III.) of a grayish colour, and partly micaceous. The mount- 

 ains of Rigaud, Beloeil, Monnoir, Yamaska, Shefford, and Brome, are 

 essentially granitic trachytes, consisting of light-coloured potash-feld- 

 spar, with small grains of black hornblende, or scales of brown or 

 black mica ; and usually containing, in addition, some small crystals of 

 yellow sphene (see Part II.) and grains of magnetic iron ore. Much 

 valuable information on the composition of these picturesque and in- 

 teresting mountains, is given by Professor Sterry Hunt, in the Geolo- 

 gical Report for 1859. See also the Canadian Journal, Vol. V., 

 p. 426, and the Revised Report of the Geological Survey, 1863. 



The surface of the St. Lawrence Basin, like that of the Lake area, 

 is also very generally covered by thick accumulations of the Drift and 

 Post-glacial epochs : comprising clays, gravels, and boulders. But the 

 fossil shells, found in the upper part of these, are all of a marine or es- 

 tuary character. They are referrible to species which still exist in the 

 Gulf of the St. Lawrence, or on the coast of Labrador. These shells 

 occur, not only on comparatively low levels, but at considerable heights 

 also, above the present surface of the sea. Some of the most noted lo- 

 calities comprise the neighbourhoods of Ottawa and Montreal; terraces 

 on the Montreal Monntain : one, nearly 500 feet above the sea-level ; 

 Beauport near Quebec, about 120 feet above the sea ; and various ter- 

 races on the Lower St. Lawrence, the Ste. Anne River, the Matanne, 

 the Metis, &c., in the Gaspe peninsula, at heights varying from 40 or 

 60, to 245 feet above the present sea-level. It is evident, therefore, 

 that at the commencement of the Post-glacial or present period, \\iQ 

 entire or greater part of the St. Lawrence basin must have been deeply 

 submerged beneath the sea. 



8. The Eastern or Metamorphic Basin of Canada : — This basin, 

 forming strictly, a portion of the St, Lawrence area, is separated from 

 the latter by the great dislocation already described in §§ 5 and 7. It 

 includes the site immediately under and around Quebec, the central . 

 and southern part of the Island of Orleans, the south shore of the St. 

 Lawrence from a little west of Point Levis to near the Magdalen River, 

 and all the intervening area to the south (including the greater part of 

 the eastern townships, &c.) as far as the Province boundary. In the 

 more northern part of this region, the strata, consisting of the Calci- 

 ferous and Chazy formations (united into the Quebec group), are raised 

 along the line of the before-mentioned dislocation into a position ap- 

 parently above the horizon of the Trenton series. (See the remarks. 



