NIAGARA. 
241 
N I A G A B A 
AND ITS PHYSICAL AND GEOLOGICAL CONDITIONS.* 
BY W. P. MARSHALL, M.I.C.E. 
The great Niagara Falls are the most remarkable in the 
world on account of their enormous volume of water; they 
are exceeded in height two, three, and more times by other 
great falls, but far exceed them in the mass of water flowing 
over the falls. Niagara is the sole outlet of four out of the 
five great lakes or inland seas that divide the United States 
from Canada, and form the drainage of the enormous extent 
of country surrounding them; the largest of these lakes is 
more than 400 miles in length and 100 miles in width, and 
the whole together are as large in area as Great Britain. 
The Niagara Falls have been known for two centuries, 
having been first described by a traveller, Father Hennepin, 
in 1678, who has fortunately left an effective sketch of the 
appearance of the Falls at that time ; and a comparison of this 
sketch with the present condition of the Falls gives very 
interesting information about important changes that have 
taken place during the last two centuries. The Niagara 
Biver, in the middle of which the Falls are situated, forms 
the connection between Lakes Erie and Ontario, and the 
entire discharge from the four upper lakes, Erie, Huron, 
Michigan, and Superior, passes through the Niagara Biver 
into Lake Ontario, and thence by the Biver St. Lawrence 
into the Atlantic Ocean below Quebec. The Niagara Biver 
is about thirty miles in length, and falls 830 feet in its whole 
course, one half of the total fall or 160 feet being in the 
great Niagara Falls. 
The first portion of the river from Lake Erie is divided 
into two channels, which unite above the Falls in a quiet 
stream nearly two miles wide; this becomes contracted 
to three-quarters of a mile in width at the Horse-shoe 
Bapids immediately above the Falls, where the stream rushes 
down a steep rocky descent, and falls as much as fifty feet in 
the length of a mile, before reaching the precipice of 160 feet 
in height that forms the great cataract of Niagara. The 
water is very deep at the foot of the cataract, and 180 feet 
in depth at three quarters of a mile distance; and the force 
of the falling water is so much absorbed in that great depth 
* Transactions of the Birmingham Natural History and Micro¬ 
scopical Society. Read February 24tli, 1885. 
