286 THE HISTORY OF THE NIAGARA RIVER. 



region of hills. In places it is only the highest part of the plain ', but it 

 is nevertheless a continuous upland, else the waters would not be parted 

 along its course. When the ice had its greatest extent it passed over 

 this upland, so that the waters produced by its melting fell into the 

 Ohio and other tributaries of the Mississippi, as well as into streams 

 that discharged to Delaware and Chesapeake Bays. Afterward, when 

 the glacier gradually fell back, there came a time when the ice front lay 

 in the main to the north of the great water parting, but had not yet re- 

 ceded from the Adirondack Mountains, so that the water that flowed 

 from the melting glacier could not escape by way of the St. Lawrence 

 River, but gathered as a lake between rhe upland divide and the ice 

 front. In fact, it formed not one but many lakes, each discharging 

 across the divide by some low pass, and as the great retreat progressed 

 these lakes were varied in number and extent, so that their full history 

 is exceeding complex. 



The surfaces of these lakes were stirred by the winds, and waves beat 

 upon their shores. In places they washed out the soft drift and carved 

 clifts; elsewhere they fashioned spits and bars. These cliffs and spits 

 and other monuments of wave work survive to the present time, and 

 have made it possible to trace out and map certain of the ancient lakes. 

 The work of surveying them is barely begun, but from what is known 

 we may add a chapter to the history of our river. 



There was a time when one of these lakes occupied the western por- 

 tion of the basin of Lake Erie, and discharged across the divide at the 

 point where the city of Fort Wayne now stands, running into the 

 Wabash River and thence into the Ohio. The channel of this discharge 

 is so well preserved that its meaning can not be mistaken, and the 

 associated shore lines have been traced for many miles eastward into 

 Ohio and northward into Michigan. Afterward this lake found some 

 other point of discharge, and a new shore line was made 25 feet 

 lower. Twice again the point of discharge was shifted and other 

 shore lines were formed. The last and lowest of the series has been 

 traced eastward across the States of Ohio and Pennsylvania and into 

 western New York, where it fades away in the vicinity of the town of 

 Careyville. At each of the stages represented by these four shore lines 

 the site of the Niagara wa« either buried beneath the ice or else sub- 

 merged under the lake bordering the ice. There was no river. 



The next change in the history of the lakes was a great one. The 

 ice, which had previously occupied nearly the whole of the Ontario 

 basin, so far withdrew as to enable the accumulated water to flow out 

 by way of the Mohawk Valley. The level of discharge was thus sud- 

 denly lowered 550 feet, and a large district previously submerged be- 

 came dry land. Then for the first time Lake Erie and Lake Ontario 

 were sep^irated, and then for the firf5t time the Niagara River carried 

 the surplus water of Lake Erie to Lake Ontario. 



The waves of the new-born Lake Ontario at once began to carve 



