232 matured 



ice of the glacial period. In its movement 

 across the country which is now covered by the 

 lake the ice encountered a huge rock forma- 

 tion at Kelly's Island. Great V-shaped 

 grooves were cut through this rock by the 

 action of the ice, deep enough for a man to 

 stand in. In other places the rock was planed 

 off in the form of a great molding, a number 

 of feet wide, with the same smoothness and ac- 

 curacy as though done by a machine. 



Another effect of the glacial period has been 

 the creation of numerous waterfalls through- 

 out the glaciated area. The most notable in- 

 stance is that of the Falls of Niagara. 



In preglacial times the beds of all rivers and 

 water courses had worn down to an even slope, 

 so that there were very few, if any, waterfalls 

 such as we have to-day. As we have before 

 stated, Niagara Eiver as well as the St. Law- 

 rence Eiver is a new outlet for the drainage of 

 the great lakes. A part of this drainage for- 

 merly had its outlet through the Mohawk Val- 

 ley into the Hudson, which is now filled up 

 with glacial drift. The evidence is so con- 

 clusive that it is no longer doubted that the 

 Niagara Eiver dates from the time that the 

 ice receded from that point. When the water 

 first began to flow through this new channel 

 it plunged over the high rocky cliff at Queens- 

 town, and from that time to this it has been 

 wearing its way back to the present position of 



