122 E. W. ELLS ON THE GEOLOGY OF 



Quebec. This is evidenced by the fact that small portions only have escaped as in the case 

 of the beds at Levis, and also in that of certain limited areas of Silurian and Devonian 

 rocks, among which may be mentioned those on the Chaudière and at other points inland. 



From the relation of the fragments of the Levis formation which yet remain, it is 

 evident that the whole Quebec group after deposition hats been crumpled and folded 

 on a most extensive scale, many of the foldings being complete overturns ; and that the 

 direction of the pressure has been from the south-east. It is evident therefore that the 

 presence of apparently conformable areas of newer strata may be looked for at many points, 

 and this is precisely the case as seen in the study of the rocks in this field, where not only 

 the Levis beds but the Chazy-Trenton and even Upper Silurian formations are intimately 

 associated with the oldest rocks of the whole series. Beautiful illustrations of this can be 

 seen at Richmond and in the country sotith of Melbourne, where the Cambro-Silurian fos- 

 siliferous limestones occur, as an integral part of the schists of pre-Cambrian age and 

 where, owing to one of the great overthrust faults, the fossili ferons rocks now occupy an 

 inferior stratigraphical position. Ou the shores of Memphremagog lake also the Upper 

 Silurian beds are so completely overturned beneath the Treuton-Chazy that, were it not for 

 finding the characteristic fossils of the formation no one could from the stratigraphy, or 

 from the character of the rocks at this point, assert the newer age of the Silurian portion. 



The period of the crumpling therefore of much of this great series of rocks must have 

 been comparatively recent. On the Chairdière, in Beauce Co., fossiliferous Siluro-Devoniau 

 rocks occupy a basin-shaped area of no great extent— but in cleavage, couforming to the 

 underlying Cambro-Silurian and Cambrian rocks, and in their alteration have assumed 

 even the character of schists, in which, however, the fossils can be easily recognized. The 

 Silurian rocks of Dudswell and certain sections south of Sherbrooke are illustrations of 

 the same kind, and show clearly that all have been involved in the general scheme of 

 folding. At Dudswell the ordinary fossiliferous Silurian limestones have been changed to a 

 highly crystalline marble, while in other places a schistose structure has been imparted. 



It is important to note in this connection that in the area east of the St. Lawrence two 

 series of stratigraphie conditions are plainly seen. Thus from a point a few miles south 

 of Quebec city, a well defined line of fault crosses the river and can be traced continously 

 south-west to the foot of Lake Champlaiu. This is the great St. Lawrence and Lake Cham- 

 plain fault described in the Geol. Can., 1863, p. 2-34, and which, east of Quebec continues 

 down the St. Lawrence to Cape Rosier as already stated. The strata to the east of the fault are 

 all affected by the disturbances already described. Those to the west, with the exception 

 of the strata in the immediate vicinity of the fault, are nearly as horizontal as when first 

 deposited. This horizontality of the measures west and north of the fault extends from 

 the New York boundary northward, and eastward to the island of Anticosti. The age of 

 this fault which probably was not far removed from the period of crumpling can be very 

 closely determined ; thus, it is certainly newer than the Loraine, since it affects these 

 beds south of the city of Quebec, separating them from the Sillery. It is very probably 

 not far from the intrusion of the doleritic mountains of Montreal and the country east- 

 ward, which is not far from the Lower Helderburg time, though we have no formations in 

 the vicinity of later date to limit it definitely in this direction, and it may therefore be 

 generally stated that these great lines of fracture took place not far from the close of the 

 Silurian period, since as already shewn the Silurian strata have been involved in the 



