Reviews — Geological Survey of Canada. 85 



Areas of Devonian rocks occur at several widely separated points 

 east of the Sutton Mountain anticline and its extension northward. 

 The only outcrops of strata holding typical Devonian fossils are 

 found on the western shore of Memphremagog Lake. 



The areas of Silurian rocks found in this portion of the province 

 of Quebec are of limited extent. They comprise the basin in which 

 the lower part of Lake Memphremagog is situated, which is 

 probably the largest development of Silurian strata in south-western 

 Quebec, and outcrops of very limited extent are found also on 

 St. Helen's Island, Montreal, while in the flat country to the east 

 of the St. Lawrence, and to the south-west of Becancour Eivei', 

 Silurian rocks of an older horizon occur. The structure of the 

 Silurian in the eastern or Memphremagog Lake area is that of a 

 folded basin, resting, on either side of the lake, upon fossiliferous 

 Cambro-Silurian or Lower Trenton rocks. The rocks of the whole 

 series have been subjected to great metamorphic action since their 

 deposition, for they are highly inclined and folded, and also cut by 

 numerous dykes, often of large size. 



The complicated structure of the Cambro-Silurian rocks of 

 south-western Quebec has given rise to much controversy, and 

 its elucidation throws some light upon the much disputed question 

 as to the age of the rocks of the city of Quebec, of the Island 

 of Orleans (in tlie St. Lawrence below Quebec), and at many points 

 along the Lower St. Lawrence, as also upon the age and equivalents 

 of the fossiliferous Levis and Sillery divisions of the Quebec Group. 

 The district is traversed by extensive faults, among which is the 

 great St. Lawrence and Champlain fault, described by Sir William 

 Logan in the " Geology of Canada," which has been traced from 

 the Vermont boundary', at the foot of Lake Champlain, to the city 

 of Quebec, and thence down the St. Lawrence River along the north 

 side of Gaspe Peninsula. The result of recent researches, in which 

 palteontology has played an important part, is to show that the 

 Ktratigraphical sequence of the various divisions of the Quebec 

 Group, as interpreted by Logan, must be completely reversed, and 

 the divisions must now be read upwards from Sillery (Upper 

 I'otsdam), Levis, and lower Phillipsburg (Calciferous), upper 

 Phillipsburg, Bedford, and Mystic (Chazy), and Farnham black 

 slates and limestones (Lower Trenton). 



The classification of certain areas in the south-western portion 

 of the province as Cambrian rests, to a large extent, upon strati- 

 graphical position and lithological characters, though in regard to 

 the position of most of these rocks in the geological scale there 

 can be no doubt. The rocks consist mostly of red and green and 

 blackish-gray slates, and sandstones, which are quartzose in some 

 places. 



The pre-Cambrian rocks east of the St. Lawrence are represented 

 in the Sutton Mountain range (an extension into the province of 

 Quebec of the Green Mountains of Vermont), and at other places 

 in this area described in Dr. Ells's report. The Sutton Mountain 

 rocks consist of crystalline schists, which are gneissic, micaceous, 



