FOEMATIONS OF QUEBEC AND EASTERN ONTARIO. 25 



to the south along the line of the Canadian Pacific railway as well as in the valley of the 

 N'orth river near the western part of the village where they occupy the bed of the stream 

 from the bridge over the post-road to below the paper mills. Eastward of this place outcrops 

 of the transition beds between Calciferous and Potsdam are seen at intervals along the road 

 to St. Jerome, the Potsdam itself appearing at onlj' one observed point in the river to the 

 north between the Calciferous and the Laurentiau, the latter of which forms a bluff extending 

 nearly to the north bank of the river. 



To the south near the Ottawa river in the vicinity of the lake of Two Mountains, the 

 Potsdam and Calciferous have a much wider development. They surround the syenitic 

 mass of Mont Calvaire and on the south side of the river they are seen on the lower part 

 of the Rivière à la Graisse and the shore adjacent, in which stream at the village of Rigaud, 

 about one mile inland, the transition beds into the Calciferous are easily recognized. Here 

 they are penetrated by the mass of Rigaud mountain beyond which they continue to the 

 south and east and connect with the St. Lawrence area which extends across from the state 

 of New York. 



Throughout the distribution of the Potsdam sandstone as just given, it, for the most 

 part, rests directly upon the Laurentian. îTo rocks carrying a Primordial or Cambrian 

 fauna proper can be recognized at any point in the St. Lawrence or Ottawa basins in 

 Canada. The strata are for the most part nearly or cpiite horizontal, but the presence of 

 several low lying anticlinals can be observed in the area between the St. Lawrence and Ottawa 

 rivers, the dips of the strata rarely exceeding five degrees. In this direction the succession 

 ujiward can be traced into the Hudson River formation, more particularly in the vicinity of 

 Montreal and the area lying eastward towai'd Chambly. 



Descending the St. Lawrence river between Montreal and Quebec, the Potsdam 

 disappears, the Laurentian being directly overlaid by the Calciferous and this in turn by the 

 Chaz}' and Trenton. The direct superposition of the Trenton formation upon the Archœan 

 is beautifully displayed at the Rivière Ste. Anne de Montmorency where, a short distance 

 above the falls, the lower part of the fossiliferous Trenton consists, for several feet, of beds made 

 up of the debris of the Laurentian gneiss, giving it a somewhat coarsely quartzose aspect. 

 These arkose beds fill up the inecpialities in the gneiss floor and pass rapidly ujiward into the 

 highly fossiliferous limestone of the Trenton formation. 



Beyond this to the eastward the typical Potsdam rock does not appear fi)r many miles, 

 in fact not till we reach the strait of Belle-Isle. Certain outliers of the Calciferous are seen at 

 the Miagan islands, but their superposition upon the Potsdam, which should occur between 

 these and the Laurentian gneiss, has not yet been clearly recognized. Loose pieces of 

 quartzite and sandstone appear along the shore and render it proliablc that the Potsdam 

 formation may occiir here in its proper place at some point. At Murray bay also certain 

 beds of quartzite are seen which were on first examination supposed to belong to this forma- 

 tion, but which upon more careful investigation appeared prol)al)ly to 1.)e part of the quartzite 

 formation of the Upper Laurentian. 



Typical Potsdam sandstone does not appear either in îfova Scotia or New Brunswick, 

 though Cambrian sediments with well defined fossils are found in both provinces. These 

 fossiliferous strata consist of slates, limestones, cpiartzites, etc., which are vei-y distinct in 

 physical character from the Potsdam of Ontario and Quebec and belong most certainly to a 



Sec. IV., 1894, 4. 



