24 THE CAMBRO-SILURIAN, OR ORDOVICIAN. 



Much new information as to the subdivision and character of the 

 Silurian in New Brunswick and Nova Scotia appears in the Reports 

 of Bailey and Fletcher above referred to ; and in my paper on the 

 iron-ore deposits I have given further facts as to the fossils. 



VI. THE CAMBRO-SILURIAN, OR ORDOVICIAN. 



With the incoming of this age a more marked distinction occurs in 

 America between the marginal and plateau-deposits. This had 

 previously appeared in the Cambrian, and becomes more distinct in 

 the Erian and Carboniferous, but it is somewhat peculiar as between 

 the marginal and submarginal areas and those inland in the period on 

 which we now enter. 



In Newfoundland, Murray and Howley have described large areas 

 of Quebec group rocks in the west and north of the island, which seem 

 to be continuations of the submarginal area of the Lower St Lawrence. 

 There is also one limited exposure of Trenton Limestone on the west 

 coast, which may be regarded as belonging to the area of the Gulf of 

 St Lawrence, 



So far as our present subject is concerned, it is sufficient to observe 

 that the Quebec group is not strictly an outer marginal formation, but 

 rather submarginal, and belongs to a period when the principal area 

 of coastal deposition of sediment from the north was inland of the 

 Acadian provinces, or between them and the main American plateau, 

 and separated from the outer ocean by a belt of active volcanos. Its 

 conditions of deposit and characteristic fossils may fairly be compared 

 with those of the Skiddaw and Arenig of England.* The Ordovician 

 series of Shropshire extending upward from the Stiper Stones to the 

 Caradoc is also a counterpart of the Quebec group.f 



Of Ordovician rocks other than the Quebec group and nearer to 

 the Atlantic margin, perhaps the best example is that of the area in 

 Central and Western New Brunswick described by Prof. Bailey. | 

 This consists, in ascending order, of {1} gneiss and mica-schist with 

 chloritic and hornblendic schists, (2) gray and purplish micaceous 

 sandstones and slates with limestone and conglomerate and felspathic 

 slates, (3) black graphitic and pyritous slates, (4) schistose felspathic 

 rocks and conglomerates, (5) amygdaloid and felsite with sand.stone 

 and slate, (6) felsites capped with sandstones and slates, often 

 chloritic. These remarkable rocks, which are of great thickness and 



* Hicks, Classification of Lower Palaeozoic Kecks, 1881. 



■f Lapworth, Geol. Magazine, 1887. 



I Report Geological Survey of Canada, 1884-5. 



