terfalls
were once frequent in the valleys of Switzerland; for hardly any
valley is without one or more transverse barriers of resisting
material, over which the river flowing through the valley once fell as
a cataract. Near Pontresina, in the Engadin, there is such a case; a
hard gneiss being there worn away to form a gorge, through which the
river from the Morteratsch glacier rushes. The barrier of the Kirchet
above Meyringen is also a case in point. Behind it was a lake,
derived from the glacier of the Aar, and over the barrier the lake
poured its excess of water. Here the rock, being limestone, was in
part dissolved; but added to this we had the action of the sand and
gravel carried along by the water, which, on striking the rock,
chipped it away like the particles of the sand-Blast. Thus, by
solution and mechanical erosion, the great chasm of the
Finsteraarschlucht was formed. It is demonstrable that the water
which flows at the bottoms of such deep fissures once flowed at the
level of their present edges, and tumbled down the lower faces of the
barriers. Almost every valley in Switzerland furnishes examples of
this kind; the untenable hypothesis of earthquakes, once so readily
resorted to in accounting for these gorges, being now for the most
part abandoned. To produce the Canons of Western America, no other
cause is needed than the integration of effects individually
infinitesimal.

And now we come to Niagara. Soon after Europeans had taken possession
of the country, the conviction appears to have arisen that the deep
channel of the river Niagara below the falls had been excavated by the
cataract. In Mr. Bakewell's 'Introduction to Geology,' the prevalence
of this belief has been referred to. It is expressed thus by
Professor Joseph Henry in the 'Transactions of the Albany Institute:'
[Footnote: Quoted by Bakewell.] 'In viewing the position of the
falls, and the features of the country round, it is impossible not to
be impressed with the idea that this great natural raceway has been
formed by the continued action of the irresistible Niagara, and that
the falls, beginning at Lewiston, have, in the course of ages, worn
back the rocky strata to their present site.' The same view is
advocated by Sir Charles Lyell, by Mr. Hall, by M. Agassiz, by
Professor Ramsay, indeed by most of those who have inspected the
place.

A connected image of the origin and progress of the cataract is easily
obtained. Walkin