Science, Geology and Physics 



Appalachian coal fields northerly, discharging through the Dun- 1901 

 das Valley into Lake Ontario. 



5. First ice age, that of the Cordilleras. Not certain that its 

 influence was felt in the Niagara region. 



6. Second ice age, the Keewatin. Blocking up of Erigan 

 River. Ice moves southerly ; its melting gives birth to Lake Erie. 



7. Temperate epoch. Wearing of the gorge through the St. 

 David's channel, including the whirlpool, 3,960 years. 



8. Accumulation of ice upon the Labrador highlands and its 

 movement southwesterly, as far south as to the Ohio River, fill- 

 ing the St. David's Channel. Terminal moraines left as it 

 recedes ; one near Buffalo, and the next from Lockport across to 

 Toronto. 



9. Warren Lake, discharging at Chicago, occupying parts of 

 Lakes Michigan, Huron and Erie. 



1 0. Algonquin Lake was composed of Lakes Superior, Michi- 

 gan and Huron, discharging into the Ontario basin through Lake 

 Erie, or by way of Balsam Lake and Trent River, and thence 

 through the Mohawk into Hudson River. . . . 



1 1 . Iroquois Lake, as expanse of Lake Ontario succeeded, 

 discharging through the Mohawk. Beginning of the erosion of 

 the lower gorge. River divided by the island below Wintergreen 

 flat. Time of erosion 6,844 years. 



12. Erosion of the Cove section requiring a river as large as 

 the present Niagara. Breaking of the barrier at outlet of whirl- 

 pool. Time, 937 years. 



13. Period of erosion of the gorge of the whirlpool rapids, 

 when the water of Lake Erie alone was concerned. Outlet of 

 upper lakes perhaps through Lake Nipissing. Time, 7,800 years. 



14. Restoration of full volume of Niagara River. Upper great 

 gorge excavated from the railroad bridges to the existing cata- 

 ract. Time, 2,962 years. 



Time since the water fell over the Niagara escarpment, 

 1 8,91 8 years. Between this epoch and the shifting of the Labra- 

 dor ice-sheet from the Niagara River valley there intervened 

 Lakes Warren and Algonquin (events 9 and 10), probably not 



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