No. l.J SELWYN — THE QUEBEC GROUP. 19 



No. 1 consists of a great variety of slates or shales (argillites), 

 red, green and black ; limestones, in thin bands ; limestone con- 

 glomerates, sandstones and quartzites. In every part of their 

 distribution from the Vermont boundary to Gasp<3, 500 miles 

 they hold a large number of genera and species of characteristic 

 Lower Silurian fossils, full descriptions of which have been o-iven 

 in the reports of the Geological Survey. This fossiliferous belt 

 occupies a strip of country on the south side of the St. Lawrence 

 which in its widest part, in the valleys of the Chaudiere and the 

 Etchemin does not exceed twenty-five miles, and in this portion 

 the structure presented is that of a broad crumpled and folded 

 synclinal with prevailing south-easterly dips on the north-western 

 side, and north-westerly dips on the south-eastern side; the 

 characteristic Point Levis limestone conglomerates comina; up 

 near the base on both sides. There are doubtless a number of 

 local and unimportant overturn dips, but there seems to be no 

 evidence whatever of a general inversion of the strata. 



On the north-western side this belt is bounded by the St. 

 Lawrence and Champlain fault, or overlap, which brins^s the 

 even-bedded shales and limestones of the Hudson River or Lor- 

 raine Shale group into contact with the crumpled and twisted 

 strata of the Levis formation. The line of this dislocation or 

 unconformity — whichever it may be — has been supposed to pass 

 in rear of the Quebec citadel. This I hold to be a mistake, 

 and I think it can be distinctly shewn that it passes from the 

 south-west end of the Island of Orleans under the river and 

 between Point L^vis and Quebec ; it appears again on the north 

 shore about one mile north of Point Pizeau, passes north of St. 

 Foy, and thence in a direct course to where it again crosses the 

 river south-west of Cap Rouge. The entire absence of Levis 

 fossils in the Citadel rocks is thus easily explained. I have 

 traced this break carefully from the last-named point on the 

 north shore of the St. Lawrence to the north-east end of the 

 Island of Orleans, where on the beach the actual contact of the 

 two formations is well seen, and a short distance inland we find 

 the characteristic Levis limestone conglomerate. JSalterella and 

 Archmocyathus occur both at Point Levis and on the Island of 

 Orleans, and the graptolite {PhylogrcqHus) shales are interstrati- 

 fied both above and below the limestone conglomerates. Oholella 

 occurs also in shales clearly above the conglomerates and below 

 other shales holding graptolites, and in some beds both occur 

 together. 



