94 



north, passing through Gaspe, curving at its termination 

 in an arc, convex northward : thus: 



Orogenic Appalachian axes. Gulf of St. Lawrence. 



The torsion of the northern fold, ascribable to the 

 resistance of the Labrador shield, produced a syntaxis 

 which broke down that fold and dislocated the bottom of 

 the Gulf area in a line continuous in direction with the 

 course of the fold. Thus with the fracture of the pavement 

 of the region and the consequent differential elevations and 

 depressions, the St. Lawrence waters took somewhat the 

 course now indicated by the hydrographic chart; probably 

 for a part of the time or by way of a subsidiary channel 

 taking the passage out by the Strait of Belle Isle and 

 bending about Anticosti island to the north and east. 

 This was thus a secondary condition of the river, dating 

 to a time subsequent to the uplift of the folded Palaeozoic 

 rocks. Since that time, the broken down Gulf region has 

 successively been a river way, an open marine body, an 

 estuarine basin, and again a more or less enclosed sea. 

 After the recoil of the northern fold which broke down the 

 regularity of the mountain building and left the parma of 

 horizontal rocks at the north (Anticosti island), came a 

 period of rough rias coast along the broken ends of the 

 Appalachian folds with a sea which received the mantle 

 of Bonaventure conglomerate, when the marine waters had 

 a far wider westward extent than to-day and the river 

 channel south of the latitude of Perce was deeply buried. 

 This period was followed by a shallowing of the basin 

 which brought on the estuarine conditions of the coal 

 period, with occasional irruptions of marine conditions; 

 then a still farther elevation of the gulf bottom, which 



