OUTLETS OF THE ST. JOHN RIVER. 65 



■correct to speak as the original St. John, is that whicli 

 flows in tlie Kennebecasis and Petitcodiae valle}'. It is 

 one which apparently, in the early part of the Carboni- 

 ferous age, had its discharge eastward ; but which, after 

 the long period of continental ui:)lift, if not earlier, through 

 the breaking down of the land barriers near St. John, 

 found an outlet to the south. 



Thus we see that the St. John river has attained its 

 present magnitude by the breaking of mountain or hill- 

 barriers which once separated its three river systems, 

 and is not a simple valley of continuous growth like the 

 Mississippi. Great changes of level of the earth's surface 

 were required to bring about this condition of things, 

 and these changes were to a large extent aifected during 

 the period of continental elevation to which I have re- 

 ferred. Xot all of them, however, for very important 

 ones w^ere produced when the former warm-temperature 

 climate was exchanged for one of arctic cold, and glaciers 

 ■of wide extent overspread the land. 



AcTio^ OF Glacial Agencies Upon the River Courses. 



The long period of continental elevation, coupled with 

 the warm temperature which prevailed during the greater 

 part of it, had decomposed the rocks to a great depth, 

 and when glaciers invaded the land the}' found it an 

 easy task to remove great masses of this loose covering. 

 This debris was carried along by the moving ice and 

 eventually deposited at the sides and at the foot of the 

 glaciers, across many of the valleys and ravines, and left 

 there when the ice melted away. These deposits were 

 modified during a period of submergence, but not greatly 

 changed, and as the land again arose to its original level, 

 first beds of sand and gravel and then beds of clay were 

 •deposited in all the valleys, forming a luting \vhich 



