NIAGARA AS A TIMEPIECE. 



13 



broom had swept the accumulated dirt of ages from the northern 

 country and filled up the great valleys, the lake region was cov- 

 ered with water ; whether arms of the sea, as is probable, or as 

 lakes, of which the barriers are not indicated, is immaterial in the 

 history of the river, for under either condition the old shores were 

 produced, and these we have surveyed. From them we learn the 

 story that all the lakes formed one broad sheet named the Warren 

 water. From time to time its surface was lowered, and at each 

 pause new stands were formed, only to be abandoned by further 

 sinking of the water. At last the aboriginal Warren water sub- 

 sided so that it became divided in two smaller sheets — the Algon- 

 quin gulf, occupying more or less of the basins of Lakes Huron, 

 Michigan, and Superior, and the Lundy gulf, extending over 

 much of the Erie and the Ontario basins. With the continued 

 lowering of the gulf, or, more correctly, the rising of the land, for 

 no evidence of lake barriers has been found, the Lundy gulf be- 

 came dismembered, forming Lake Erie, then much smaller than 

 now, and the Iroquois gulf occupying the Ontario basin, the de- 

 serted shores of which have now an elevation much above the 



Fui. \Z. \'lEW OF THE AmEKICAN FaI.I.S. 



present altitude of the lake. Then Niagara Falls had their birth, 

 and the river descended only a little more than half as great a 

 height as to-day into the gulf (Fig. 10) which came to the mouth 

 of the gorge. The lowering continued until the descent of the 

 river was much greater than at present, and the shores of the lake 

 receded not merely eight miles to the present margin of the 



