334 BREACHES I A THE INN 



where the two just-mentioned riyers unite with tho 

 Ohio. 



From this point, the eye of the inquirer looks over a 

 wide gap or long tract of prairie, towards the hills which 

 skirt the Illinois river, and the mountains west of cape 

 Girardeau, beyond the Mississippi, probably furnishing 

 the only remaining vestiges of the ancient barrier. 



This grand rampart has, in the course of ages, been 

 broken through in several places. I shall mention the 

 principal breaches that have oorne to my knowledge. 



1 . The breach at the northeastern extremity of lake 

 Ontario. 



The thousand islands, and the whole of the scenery in 

 their vicinity, bear witness of the mighty rush of waters 

 which at some former period prostrated the opposing 

 mound, and left them as scattered monuments of the ruin. 

 This must have contributed to lower lake Ontario to the 

 level of its outlet, or to its present bed. By this opera- 

 tion the water must have subsided about one hundred and 

 sixty feet from the height of the ridge road between the 

 Niagara and Genesee rivers, so beautifully described 

 by Dr. Clinton.* All the country on both the Cana- 

 dian and Fredonian sides must have been drained and 

 left bare on the occasion, exposing to view the water- 

 worn pebbles, the works of marine animals, their solid 

 parts buried in the soil, their relicks bedded in the rocks, 

 and the whole exhibition of organic remains formed in 

 the bottom of such a sea as that was. 



* Introductory Discourse before the New-York Literary and Philo 

 sophical Society, note G. 



