502 J. A. DRESSER IGNEOUS ROCKS OF EASTERN QUEBEC 



boundary line. It has a considerable development in the counties of 

 Sutton, Brome, Shefford, Richmond, Wolfe, Arthabaska, Megantic, 

 Beauce, Dorchester, and probably extends also into Bellchasse and Mont- 

 magny — that is, to a point at least 140 miles from the boundary of the 

 state of Vermont. 



The rocks of the Sutton Mountain area were described by Logan* as 

 "chloritic, micaceous and epidotic rocks. Towards the province line," he 

 continues, 



these are of a slaty character and various shades of color, from dark bluish- 

 green or blackish-green to ash grey. The green bands are more abundant than 

 the grey, and both have occasionally a talcoid lustre. The grey bands appear 

 to derive their color from a large amount of very fine grains of quartz which 

 are uniformly mixed with chlorite. These beds often contain certain nodules 

 of white granular quartz, and crystalline pistachio-green epidote sometimes 

 several inches in diameter, and frequently elongated in parallel directions. The 

 two minerals are often in separate nodules, but as often are intermixed; in 

 the latter case the epidote is generally within the quartz. In the grey bands, 

 fine blackish-green lines of chlorite often run parallel to one another, but 

 these are contorted by the nodules of quartz and epidote, with which orthoclase 

 feldspar is sometimes associated. 



Radiated actinolite often occurs in the rocks together with asbestos in short 

 parallel veins, which are found cutting the epidote in the direction in which 

 the nodules are elongated, and occasionally between the layers of slate. Crys- 

 tals of specular and magnetic oxide of iron are abundant in the chloritic and 

 epidotic bands, the magnetic species being more frequent where the chlorite 

 prevails. 



Near the Saint Francis, nodules of an epidotic character are richly dis- 

 seminated through the chief part of these chloritic strata, some of the nodules 

 being six, eight and even ten inches in diameter. Some of the bands hold small 

 portions of finely granular quartz which occasionally swell into beds of white 

 quartzite of some importance, while many of the strata assume the aspect of 

 fine quartzose curglomerates or coarse sandstones with a chloritic base. 



Regarding the rocks of the Stoke belt, Logan writes :f 



The rocks of this group here at the base of Owls Head mountain, branching 

 off from a range of hills which come up from Vermont into Canada, take a 

 northeasterly direction, and crossing Memphremagog lake run from the town- 

 ship of Stanstead through Stoke to Weedon, and constitute the Stoke moun- 

 tains, which are bounded on each side by more recent strata just mentioned. 

 The average breadth occupied by the Quebec group in these hills seldom 

 exceeds 2 or 3 miles, except in Ascot and Stoke. On the Saint Francis in the 

 former township, through the influence of these undulations, the Quebec rocks 

 have a transverse measure of 7 miles extending from the vicinity of Lennox- 



* Geology of Canada, 1863, p. 246. 

 f Geology of Canada, p. 252. 



