298 The American Geologist. November, 1894 
amount at the outlet of lake Ontario, but almost zero at tin- 
bead of lake Erie. 
IS. History of the Niagara Hirer and Changes of the Out- 
lets of the Lakes. From a recently written paper I make the 
following extracts, concerning the changes and recession of 
Niagara falls (Plate VIII). Upon the dismemberment of 
Lundy water, the Niagara river came into existence, and for 
a time (taken as 1,000 years) drained the infant lake Erie 
without cascading over a fall. The waters of the lower lake 
slowly sunk so that the total hight of the fall was 200 feet, 
with only the drainage of the Erie basin, or about ^ r of the 
modern volume of the water. The early falls are almost ex- 
actly reproduced in the magnitude of the American falls. The 
duration of the first episode is computed at about 17,200 
years. Again the waters subsided in the Ontario basin (SO 
feet lower than now) so that the total descent was 420 feet. 
At that time the falls receded by three cascades (like the Gen-- 
esee of to-day), at first with only the discharge of the Erie 
basin and afterwards with the drainage of all the upper lakes. 
This condition is computed to have lasted 10,000 years. Then 
succeeded one united fall of 120 feet, which lasted 800 years. 
Finally the northeastern part of the Ontario basin rose soth;it 
the descent of the river waters was reduced to 365 feet and 
afterwards to about 320 feet (the downfall from the head of 
the rapids above the falls to the lake below). This adds 3,000 
years to the age of the falls. Thus, it can be seen that the 
age of the Niagara river is computed to be 32,000 years. It is 
now well established that the three upper lakes have dis- 
charged only a comparatively short time into the Erie basin, 
having formerly sent their waters to the Ottawa river. This 
change in the direction of the outlet is calculated at 8,000 
years ago, when the northeastern terrestrial tilting turned the 
drainage into the Erie basin. 
About fifteen hundred years ago, the differential uplift in 
the Niagara district and the recession of the falls through the 
Johnson ridge, a short distance below the present site of the 
falls, were competing for the masteiy, and in the meanwhile 
the four upper lakes rose so high as to commence to send their 
waters to the Mississippi river. But the ridge was cut through 
and the waters were lowered to the exclusive Niagara drain- 
