130 PROCEEDINGS OF THE CALIFORNIA 
fact, the whole western slope of the American continent, from the Pacific 
shores to the summits of the Andes, Cordilleras, and Rocky Mountains, was 
in active eruption and voleanic disturbance. 
If no other parts of the world had been subjected to like disturbances, the 
vaporization of the waters along this one great zone would have been suffi- 
cient to modify its climate; but other portions of the globe were disturbed 
to nearly an equal extent. And there can be no doubt about the effects of 
such enormous evaporation of the waters on the climate of every part of the 
earth; even tropical countries would be covered with snow if the vapors were 
sufficiently abundant and dense to exclude the heat of the sun‘for a series of 
years. The influence of the trade winds or great general currents of the 
atmosphere, must not be lost sight of; they were the conveyers and distrib- 
utors of the vapors produced by the escape of interior heat at the various 
points of disturbance. 
By tracing their general courses from such lines of disturbance, it is easy 
to determine where the greatest deposits of snow would accumulate and 
form the continental glaciers. 
I have said that nearly all traces of tertiary animal life, were swept from the 
American continent. But such does not seem to be the case with Africa, 
India, and a part of Asia; there the elephant, rhinoceros, and many other 
types of life closely allied to the tertiary mammals, remain. 
This important difference in the present types of life of the two hemi- 
spheres can be accounted for upon the general basis of the theories advanced 
in this paper. The course of the return trade winds, or upper currents of 
the air, is toward the east, but constantly diverging north and south from the 
equatorial line. The American continent is narrow in the equatorial zone, 
except a portion of South America. 
The great volcanic activity along the Pacitic slope overwhelmed the low 
lands with floods of water of such enormous volume, that nearly all land 
animals were swept off or buried in the debris from the mountains. There 
is no doubt but all the highlands of the tropical portion of South America 
were buried deep in snow, if not with glaciers. Now take the line of the 
upper air-currents across the Atlantic to the coast of Africa, and you will see 
that the divergence of these currents north and south will divide the vapors, 
and leave Africa comparatively free from their effects. The west coast of 
that continent was but slightly disturbed by volcanic activity, and there was 
not enough local vaporization along its west coast to give it a glacial system 
or flood period of sufficient volume to destroy its land animals completely. 
The same may be said of portions of Asia and India. Hence the preserva- 
tion of leading tertiary types in the Eastern Hemisphere, and their almost 
complete destruction in America, must be attributed to the operation of the 
atmospheric currents in conveying the vapors away from some portions of the 
land, while they covered other portions to great depths in snow and ice. 
Some geologists assert that many of the tertiary mammals existed in North 
America after the close of the glacial epoch. This opinion should be received 
with great caution, for the reason that such remains were preserved in the ice 
and snow of the glacier period; and as the glacial fields slowly moved down 
mountain slopes and melted away in later times, the skeletons would be 
