NIAGARA FALLS AND VICINITY 77 



been formed by a river and cataract similar to the Niagara of today, 

 during interglacial time. That this old channel was once occupied 

 by ice is shown by the glacial scratches on the limestone ledges ex- 

 posed in the western wall of the old gorge, where this has been 

 cleared of drift by Bowmans creek, and it is apparent that the filling 

 in by drift must have occurred after the ice occupation. An in- 

 spection of the map will show that a part of the present Niagara 

 gorge, that containing the whirlpool rapids, is in direct continuation 

 of the old St Davids channel, and that, a little above the railroad 

 bridges, the Niagara makes a pronounced bend, which brings it in 

 conformity with the direction of this channel. This suggests that 

 there was at least a shallow depression, the insignificant southeast- 

 ward continuation of the St Davids channel, which guided the 

 waters of the Niagara in this direction. Here a question of great 

 importance in the history of the Niagara presents itself. Did the 

 ancient St Davids gorge end where is now the south side of the 

 whirlpool, with only a shallow surface channel extending beyond 

 this point, or was the gorge of the whirlpool rapids a part of the 

 old St Davids channel, which was merely cleared by the Niagara 

 of the drift that filled it? The latter condition was assumed to be 

 the true one by Dr Julius Pohlman of Buffalo, a pioneer in the study 

 of the Niagara gorge and the first to recognize the complexity of 

 the channel and attempt to account for its varying character. The 

 theory is still held by many geologists. On the other hand, Taylor 

 and others think it more likely that the ancient gorge stopped where 

 is now the inlet to the whirlpool, and that the gorge above it is 

 the product of post-glacial erosion. If this view be accepted, the 

 narrowness and shallowness of the gorge of the whirlpool rapids 

 must be accounted for by some change in the volume of water dur- 

 ing its formation. Taylor, who has studied this problem, has come 

 to the conclusion that, during the time that the gorge of the whirl- 

 pool rapids was being excavated, the upper great lakes (then united 

 into Lake Nipissing) discharged by way of the Nipissing-Mattawa 

 river as already outlined, and that therefore Niagara drained only 

 the shallow Lake Erie, the amount of water in the river being only 

 one eighth its present volume. It is easy to see that such a reduc- 



