250 Canadian Record of Science. 
sands, not only on the river banks, but carrying them to 
these lakes and to the ocean in vast quantities; the ocean 
and lakes were themselves not only great factors in erosion 
on their coasts, but were the distributors of sands and clays 
over great areas of their floors; whilst added to these eroding 
powers were the ceaseless forces of the atmosphere in the 
heat of summer, in the frosts of winter, in the downpours 
of rain, and in the blasts of the storm—each contributing its 
measure of energy in the wearing down of mountain sides 
and cliffs, the carrying away of soil, and exposing of 
vegetation to decay—an energy not especially visible in its 
effects in a single year or in a decade of years, but produc- 
tive of vast results in the course of centuries. And this 
growth, disintegration and decay going on ceaselessly from 
century to century, and from age to age, must have created 
immense deposits of boulders, gravel, sand and clays, in 
every part ofthe country, prior to the advent of the glacial 
period. If Croll’s view were accepted, that since a p!evious 
glacial epoch, which he appears to suggest occurred during 
the Kocene age, a period of 2,500,000 years has elapsed, we 
can form some conception of what must have been the re- 
sults of denudation during the enormous time previous to 
as well as since that age. These deposits were no doubt 
largely added to, and in many cases re-arranged, but the de- 
nuding effects of the glaciers, considerable as they may 
have been on the superficial features of the country, have 
been greatly exaggerated. 
Again, some geologists have been too ready to accept ex- 
isting levels as the basis on which to found conclusions 
regarding the levels of the country in its different sections 
in past times, without any reference to warpings of the 
strata which have since affected local or wide areas. These 
warpings are known to have cut through the channels of 
rivers, created new watersheds, opened up new river valleys, 
and reversed the currents of lakes. Spencer has recently 
drawn attention to such warpings in the Mississippi Valley 
and south of Lake Ontario. 
