NIAGARA. 203 



The annexed highly instructive map has been re- 

 duced from one published in Mr. Hall's e Geology of 

 New York.' It is based on surveys executed in 1 842, by 

 Messrs. Gibson and Evershed. The ragged edge of the 

 American Fall north of Groat Island marks the amount 

 of erosion which it has been able to accomplish, while 

 the Horseshoe Fall was cutting its way southward across 

 the end of Goat Island to its present position. The 

 American Fall is 168 feet high, a precipice cut down, 

 not by itself, but by the Horseshoe Fall. The latter in 

 1842 was 159 feet high, and, as shown by the map, is 

 already turning eastward, to excavate its gorge along 

 the centre of the upper river, p is the apex of the 

 Horseshoe, and T marks the site of the Terrapin Tower, 

 with the promontory adjacent, round which I was con- 

 ducted by Conroy Probably since 1842 the Horse- 

 shoe has -worked back beyond the position here assigned 

 to it. 



In conclusion, we may say a word regarding the 

 proximate future of Niagara. At the rate of excavation 

 assigned to it by Sir Charles Lyell, namely, a foot a year, 

 five thousand years or so will carry the Horseshoe Fall 

 far higher than Goat Island. As the gorge recedes it 

 will drain, as it has hitherto done, the banks right and 

 left of it, thus leaving a nearly level terrace between 

 Goat Island and the edge of the gorge. Higher up it 

 will totally drain the American branch of the river ; the 

 channel of which in due time will become cultivable 

 land. The American Fall will then be transformed into 

 a dry precipice, forming a simple continuation of the 

 cliffy boundary of the Niagara gorge. At the place 

 occupied by the fall at this moment we shall have the 

 gorge enclosing a right angle, a second whirlpool being 

 the consequence. To those who visit Niagara a few 

 millenniums hence I leave the verification of this pre- 



