Spencer — Another Episode in the History of Niagara. 447 



about 70 feet. These gravels are very thickly strewn upon the 

 almost flat surface down to an altitude of about 50 feet above 

 the lake, surmounted by low ridgelets. It extends as a zone 

 eastward of the river and marks the gradual lowering of the 

 lake, which at the mouth of the gorge is more strongly marked 

 by the terrace (at 50 feet) and capping ridge of gravel (seen 

 also at the site of the Church at Queenstown. It is seen at the 

 St. Catherine's to the west. The Niagara Strand, east of the 

 Irondequoit Bay, is represented by a sand terrace faintly sepa- 

 rable from other delta deposits. West of Great Sodus Bay, 

 it forms a strong terrace at about 40-50 feet above the lake, sur- 

 mounted in places by a sand beach rising to 65-70 feet. At 

 other points it is seen as the terrace plains of valleys. 



The cause of the temporary rise of the waters of Lake 

 Ontario is easy of explanation. From the excessive tilting of 

 the earth's crust at the outlet of Lake Ontario, the water in 

 the Niagara district rose (in so far as it affected the physics of 

 the river) from a level 80 feet below that of the present day to 

 about 75 feet higher than now. The subsequent withdrawal 

 of the water was brought about by the St. Lawrence River 

 cutting a deeper channel for itself, largely out of drift deposits, 

 thus lowering the water of the lake to its present level. These 

 conclusions are based upon the following evidence. The 

 present channel of the St. Lawrence ordinarily varies from 60 

 to 80 feet, but there are deeper holes, one of which reaches a 

 depth of 228 feet. In passing through the islands below the 

 outlet of Lake Ontario, one is constantly observing fragments 

 (sometimes of limestone rock) of the former bed of the river, 

 now raised from 5 to 10 feet above its surface. But the first 

 rocky barrier now crossed by the river is at the Galops Rapids, 

 75 miles below the outlet of the lake. The narrowest part of 

 the river is here half a mile wide, with a depth, even on the 

 rapids, of from 30 to 45 feet. Before the removal of the bar- 

 rier by the river dissecting it, the water stood at from 100 to 

 140 feet above the present level. Many remaining points on 

 the islands in the river rise to about a hundred feet or more. 

 Upon the southern side of the St. Lawrence as at Cape Yin- 

 cent, there is a series of terraces at 30, 40-45, 50-60, 80, and 

 90-100 feet within a mile and quarter of the shore. The 

 northern shore rises to 100 feet, close to the river. The 

 country at this height, or at slightly greater altitude, forms 

 plains often miles in width, and extended across the channel of 

 the St. Lawrence River, which is a groove excavated out of it. 

 The material removed from the channel was largely drift, but 

 not entirely. The plains characterizing the surface of the bar- 

 rier to the Ontario basin are often in the form of terraces, 

 bounded by abrupt steps (old shore lines or banks) rising to 

 those of higher levels — notably at 90, 115, and 140 feet above 



