Science, Geology and Physics 



picked up loose particles, but also scoured and wore away solid 1908 

 rocks along its bed. Thus the whole configuration of the country Hulbert 

 was changed. 



At the southern terminal of the glacier, where it ended in the 

 ocean, the ice broke away in large bergs, as in the northern 

 seas to-day ; but where the advancing ice met the warmer climate 

 on land, it was melted and thus deposited at its terminal all the 

 material it carried. The eroding power of this ice sheet, together 

 with the deposit of its materials on melting, brought about a 

 great change in the configuration of the country. Many old 

 valleys were obliterated, while a number of new ones were 

 carved. As the ice retreated northward with the change of 

 climate, new lakes and rivers were formed. Many times the 

 streams escaping from the lower level of lakes were forced to 

 find an entirely new course, and so to carve a new channel of 

 their own. The region of the Great Lakes and the Niagara 

 River is no exception to this rule; and it is with the ending of 

 the Ice Age that the history of the river begins. 



A glance at a map shows a low range of hills or rather a 

 gentle swell in the land surface forming the watershed between 

 the lakes and the streams flowing to the south. At the time of 

 the farthest southerly extension of the glacier it reached beyond 

 this elevation; and its waters were discharged into the rivers 

 flowing to the south. When the southern terminal had retreated 

 to the north of this divide, but still blocked all outlet to the 

 north or east, there was doubtless a number of lakes here dis- 

 charging their waters across the present low watershed to the 

 south. Some of these ancient valleys can still be traced for long 

 distances of their course. These lakes passed through their 

 varying history as those of to-day, their surface troubled by wind 

 and storm and their waves leaving indelible carvings upon their 

 shores. 



One of these lakes occupied what is now the western end of 

 Lake Erie, shortly after the ice front had passed to the north 

 of the watershed mentioned. There are still very definite mark- 



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