128 PROCEEDINGS OF THE CALIFORNIA 
where they curve under and azain become the lower currents on their return 
to the equatorial zone. 
If the globe was a perfectly smooth sphere of homogeneous material like 
water, the atmospheric currents could be mapped out with mathematical ac- 
curacy; but the unequal surface of the land and the different thermal effects 
of land and water surfaces produce great modifications of the wind currents 
in certain latitudes. 
This is especially the case along the west coast of the North American con- 
tinent, where the polar cnrrent swings far out to the westward over the Pa- 
cific, and the return trade wind, or upper current proper, swoops down be- 
hind it to the east and strikes the west coast, and sweeps northeastward over 
the continent. 
This fact is beautifully and conclusively proved by the trees on all the 
higher mountains from the Pacific coast to the summits of the Rocky Mount- 
ains. The scrubby trees in all exposed positions near the higher summits 
lean east and northeast; even the small twigs are bent around the limbs and 
trunk in the same direction, so that the whole aspect of the tree presents the 
appearance of reaching ont to the northeast with every limb and twig. These 
facts show that the wind does blow in that direction (N. E.) almost con- 
stantly. The general fact is well known, and I will not go into tedious details 
to prove what must be readily admitted by hundreds of careful observers. 
At the close of the tertiary age, the western slope of the continent was the 
principal scene of active volcanic disturbance. To comprehend the fearful 
extent of this disturbance, and the enormous masses of lava outflows, one 
must travel over the disturbed regions and see them. My powers of descrip- 
tion are too limited to undertake the herculean task. The whole western 
slope of the continent has been broken, crushed and distorted in every con- 
ceivable manner. Districts as large as some of the smaller States have been 
buried to unknown depths with lava and ashes. Large rivers and great lakes 
were swept out of existence by the overwhelming catastrophe. The lakes, 
rivers and oceans sent columns of hissing vapors miles in height into the 
upper air currents, where they were frozen as they were conveyed eastward, 
and spread broadcast over the more quiet eastern slope of the continent. 
Thus the waters of the Pacific coast were vaporized and spread over the con- 
tinent by the return trade winds. All living things were overwhelmed and 
buried in the sudden storms of snow. The mastodon and kindred tribes 
were buried up suddenly, with their stomachs full of food, their bodies 
loaded with fat, and not a trace of any slow process of change in climate 
from cosmical or other exterior causes. 
It was evidently no slow, starving-out process that destroyed the animals 
of tertiary times, but the sudden and overwhelming effects of a great geo- 
logical catastrophe. 
While the elephant, rhinoceros, and other large animals were being buried 
in the ashes and debris near the voleanic outbreaks on the Pacific slope, the 
same class of animals were being covered hundreds of feet deep in snow on 
the eastern slope of the continent. 
Those animals that were not buried, like Pompeii, in ashes and mud near 
the outbreaks, were overwhelmed and destroyed by the resistless floods of 
