60 FR. B. TAYLOR—ORIGIN OF GORGE OF WHIRLPOOL RAPIDS. 
has cut out a great canyon from Lewiston to the Horseshoe fall, 63 miles 
long, mostly over 300 feet deep, and more than 1,000 feet wide. When 
studied in detail it soon becomes apparent that nearly all of the gorge 
has been made by a great cataract, in volume substantially like the - 
present falls; but there are two or three parts that obviously demand 
some other explanation. One of these is the comparatively narrow and 
shallow gorge of the Whirlpool rapids, the origin of which it is the par- 
ticular object of this paper to discuss. 
There are two distinct classes of facts which contribute to the unraveling 
of the gorge history. One is derived from the study of the characters of 
the gorge itself, the other from the study of the history of the upper 
Great lakes, which are the reservoirs whence the cataract has drawn its 
power. In the interpretation of the gorge by its own characters large — 
use will be made of the comparative method. By taking as the standard 
of comparison some part of the gorge concerning the origin of which 
there is the highest degree of certainty and comparing other parts with 
it, due allowance always being made for all observable causes of differ- 
ence in the gorge characters and for all evidences of difference in age, 
the main episodes and critical points of the gorge history ought to be 
disclosed. Then by turning to the lake history and noting the changes 
of outlet, if any occurred, and noting the order of such changes, we are 
prepared to anticipate the presence and order of gorge characters corre- 
sponding to the changes of volume which the river would undergo in 
consequence of changes of outlet in the upper lakes. Thus by the corre- 
lation of causal factors with resulting characters we may finally reach the 
true history of the gorge. 
Whether or not this very desirable end is open to our attainment to- 
day depends mainly on the fullness of our present knowledge. Investi- 
gation has progressed rapidly and a great mass of facts have been gathered 
by those interested in the subject. Practically all the shores of the Great 
lakes have been explored, not exhaustively in all cases, but with sufficient 
thoroughness to bring out clearly the larger factors of their history, and 
it is believed that no event of great importance or critical bearing has 
been omitted. The gorge too has been studied with much care, and the 
correlations which have been made out between the two sets of phe- 
nomena appear to be remarkably close and complete, leaving nothing of 
importance unaccounted for on either side. 
In discussing the origin of the gorge of the Whirlpool rapids it is nec- 
essary, for the sake of clearness, to give some attention to other sections 
above and below; hence the present discussion and the accompanying 
map cover somewhat more than half the length of the gorge, or from the 
