Revieiv of Recent Geological Literature. 385 
the arch for a long time, but finally the point was reached when it 
could sustain it no longer. "The last grain of sand broke the camel's 
back.' The arch gave way or crumpled into the form of mountains, 
and as the crust was thicker at this time than any time previous, so 
were the upheavals in the form of mountains greater than any that had 
preceded them, and of course the troughs formed from the settling of 
the arch would be greater; thus the beds of the oceans settled down, 
forming deeper basins, thereby draining the polar regions and leaving 
them above water (especially was this the case around the North Pole), 
depriving them of their warm ocean currents, or water covering, and 
allowing them to cool off and begin to form ice caps. The warm cli- 
mate of the Tertiary period continued until the settling process had so 
far drained the polar regions as to allow ice to begin to form when the 
climate began to change, which change continued until the Tertiary 
merged into the Quaternary. Thus began the formation of ice which 
finally culminated in a Glacial period. The conditions present were 
these : A land foundation around the poles for ice to rest upon. The 
circulation of the ocean shut off or confined to the regions south of the 
land barrier, but having free circulation within the tropical regions. 
The ocean thus confined would become warmer than it had previously 
been. If it had been carrying a certain amount of heat to be dissipated 
around the poles, and on account of the land barriers this heat were to 
be confined south of the polar regions, what would prevent the water 
from becoming warmer? Here we have a steaming ocean to furnish 
the vapor and a cold land surface to precipitate the snow, the condi- 
tions in perfection to produce a glacial period." 
Dr. True proceeds further, to account for the geologically sudden 
and recent close of the Ice age, so far as it affected the now temperate 
latitudes, by introducing another grand cataclysm during the Cham- 
plain epoch. Here he supposes, as was suggested in 1866 by Sir John 
Evans, that, while the earth's axis probably remained unchanged in its 
direction, a comparatively thin crust of the earth may have slipped as a 
whole upon the much larger nucleal mass so that the locations of the 
poles upon the crust have been changed. 
"North America and western Europe," says Dr. True, "moved 
down put of the cold region, while northern Siberia, on .the opposite 
side of the earth, moved up into it. A slight and imperceptible move- 
ment in this direction had, no doubt, been going on for ages, as the load 
accumulated on one side of the earth, but at the time of which I am 
speaking something broke loose and precipitated a rush. A cataclysm 
was produced that submerged the North Atlantic region and southern 
part of the United States, and carried the earth beyond the point of 
equilibrium. Of course, the balance was finally established by the 
waters of the ocean, which, being free to move, rushed upon the land 
in the form of great tidal waves, which surged back and forth for a 
time, but finally settled down to a state of tranquility, while the diurnal 
revolutions of the earth went grandly on upon the old axis, with per- 
haps a slight break or variation from its usual regularity." 
