■J2 The American Geologist. i>bruary, v.m. 
Origin of the Falls coid Gorge. 
Detailed examination of the gorge and river with related 
topographic features brings out clearly two important facts 
— 1st, that the gorge has been produced entirely by the erosive 
action of the river, assisted by atmospheric agencies, and, 2nd. 
that both the falls and gorge are, geologically speaking, of 
very recent age. 
Evidences of marked stream erosion arc everywhere vis- 
ible along the margin of the river in the upper part of the 
gorge. At the Indian Arrow rapids, above the falls, the river 
has, by deflection and concentration of its flow, on the left 
bank exposed on the west side a considerable portion of bed 
rock, now a yard or more above normal w'ater level. An in- 
structive display of pot-holes is to be seen here in the hard, 
polished rock, some of them four or five feet in diameter and 
deeper than broad. A little farther down stream on the right 
bank a large pot-hole can be found about two yards above 
water-level, partially filled with decayed rock and vegetable 
mould and having in it the stump of a tree five or six inches 
in diameter. The absence of similar evidences of stream ac- 
tion along higher levels is to be noted and is due to the widen- 
ing of the gorge that has taken place through atmospheric 
agencies. The well developed joint structure of the schist 
has greatly facilitated the rapid action of these agencies in a 
climate where alternate freezing and thawing is frequent dur- 
ing the winter season, and the tumbling in of large blocks has 
produced a recession of the walls of the gorge probablvpari 
passu with the down cutting of the stream. Also the rock, 
though of a hard flint-like texture, weathers rapidly in tlie 
moist air of the gorge, the decomjxisition of the pyrite and 
feldspars allowing the quartz grains to fall apart. The 
greater width of the lower portion of the gorge bears testi- 
mony to its greater age and the longer continued action of 
these forces. The comparative youth of the gorge is indi- 
cated by the steep grade of the river and the presence and 
character of the falls as well as by the steepness of the walls. 
The immediate location of the falls is not a permanent one, 
but they are constantly working up stream at a rate that may 
be rapid enough to admit of measurement, though inquiries 
