VALLEY OF THE AMAZONS. 
227 
States and elsewhere are due to two distinct 
periods: the first of these was the glacial 
epoch proper, when the ice was a solid sheet; 
while to the second belongs the breaking up 
of this epoch, with the gradual disintegration 
and dispersion of the ice. We talk of the 
theory of glaciers and the theory of icebergs in 
reference to these phenomena, as if they were 
exclusively due to one or the other, and who¬ 
ever accepted the former must reject the lat¬ 
ter, and vice versa. When geologists have 
combined these now discordant elements, and 
consider these two periods as consecutive,— 
part of the phenomena being due to the glaciers, 
part to the icebergs and to freshets consequent 
on their breaking up, — they will find they 
have covered the whole ground, and that the 
two theories are perfectly consistent with each 
other. I think the present disputes upon this 
subject will end somewhat like those which 
divided the Neptunic and Plutonic schools of 
geologists in the early part of this century; 
the former of whom would have it that all the 
rocks w r ere due to the action of water, the lat¬ 
ter that they were wholly due to the action of 
fire. The problem was solved, and harmony 
