W. M. Davis— Gorges and Waterfalls. 123 
Art, XVII.— Gorges and Waterfalls; by W1LLIAM Morris 
Davis. 
NARROW gorges and abrupt waterfalls are seldom found in 
old countries of flat rocks and moderate elevation. Fora gorge 
opens wider and wider in the course of its natural growth, and 
becomes a broad valley in its maturity and old age; a waterfall 
decreases in height as it is worn farther and farther back, until © 
at last it remains only as a faint ripple in the almost uniform 
down-grade of its stream. Kentucky, Ohio, Western Penn- 
sylvania and New York are old land surfaces of this kind, and 
their valleys are broadly open, unless bordered by excess- 
ively hard rocks, and waterfalls seldom break the even descent 
of their watercourses, except where the great glacial accident 
of prehistoric times has disturbed their low. But within the 
glaciated area, a stream may, even in the middle part of its 
course, suddenly enter a narrow gorge, a true cafion in minia- 
ture, and leap down precipitous falls, while its fellows in the 
same neighborhood and in the same set of rocks have the usual 
Open valley slopes of regular descent. Not unfrequently these 
enough to have worn its hard bench-rock back into a 
smooth, gentle slope. The headwater streams that leap down 
the ravines in the massive mountains of southeastern Kentucky 
give examples of this kind. Falls are also sometimes, but very 
seldom, produced by faults; the cascades of the Yosemite are 
most plausibly of this kind, and some of the falls in Norway 
