DIVERSION OF THE MONTREAL RIVER 763 



a new channel that carries its Avaters all the way to its present mouth in a 

 straight course of 90 miles, which lacks only 45 degrees of being exactly oppo- 

 site to that of the upper part of the stream, as well as its former continuation 

 below the point at which the change took place ; that is to say, that at a cer- 

 tain point the course of the river was turned round through an angle of not 

 less than 135 degrees, or from a north to a southeast direction, and made 

 finally to discharge into the Atlantic Ocean instead of Hudson Bay. This 

 singular occurrence was rendered possible from the fact that in one part of its 

 course the river was barely able to pass across what has now become a low 

 divide, and that a slow rising or tilting of the land to the southward gradually 

 stopped the northward flow of the river, while at the same time the changing 

 conditions induced a process of "stream-robbing" through a dam of loose drift 

 material a short distance east of this increasing obstruction. The paper de- 

 scribed numerous facts, which, taken together, seem to prove the manner in 

 which this important and interesting phenomenon was accomplished. 



RELATIONSHIP OF NIAGARA RIVER TO THE GLACIAL PERIOD 



RELATIVE WORK OF THE TWO FALLS OF NIAGARA 



INTERRUPTION IN THE FLOW OF THE FALLS OF NIAGARA IN FEBRUARY, 



1909 



BY J. W. SPENCER 



Published as pages 433-448 of this volume. 



Discussion 



Prof. W. M. Davis asked for further information concerning the basis for 

 correlating the deposits discovered by borings with the glacial and interglacial 

 epochs. 



Prof. Lawrence Martin asked whether the several beds interpreted as 

 interglacial showed signs of weathering or not. 



Mr. F. B. Taylor : I am not familiar with the particular facts which Doctor 

 Spencer has just presented, but it is interesting to note that they appear to 

 agree so far as they go with the exposures near Toronto. It is significant as 

 bearing on the probable depth of the Saint Davids Channel that not only did 

 the boring stop without reaching rock, but if the warm-climate beds found 

 near Toronto occur here they must be at a still lower level, and so far as this 

 is indicative it suggests that rock bottom may be considerably lower. 



Doctor Spencer, in answer to Professor Martin's inquiry as to the state of 

 differential decay or oxidation of the deposits in the borings, said that such 

 observations were impossible in the partial admixture of materials brought 

 up by the operations. 



In reply to Professor Davis's question as to the interglacial deposits, he 

 stated that his paper is a correlation of the pre-Niagaran deposits with the 

 glacial and interglacial deposits on the northern side of Lake Ontario at 

 Toronto rather than with those of the Mississippi Valley. The most important 

 interglacial period is that represented by a soil with a more northern flora 

 than at present (now buried 180 feet) — at a time of enormous denudation. 



