478 THE POPULAR SCIENCE MONTHLY 



ANCIENT CLIMATES OP THE WEST COAST 



By Professor JAMES PERRIN SMITH 



STANFORD UNIVERSITY 



WE naturally look at things from the standpoint of the present, and 

 regard the existing distribution of climates as the normal one. 

 But even in our own times there are slight fluctuations of climatic 

 conditions, for we hear wonderful stories from our elders of cold winters 

 and hot summers, and tremendous storms of former years. The ad- 

 vances and retreats of existing glaciers give us surer testimony of recent 

 fluctuations in temperature and moisture, as does also the shifting of 

 the zones where wine grapes can be grown successfully in Europe. 



If we go still further back into older history we find still stronger 

 evidence of change, for in northern Africa and in central Asia there are 

 remnants of ancient cities, evidently the flourishing capitals of pros- 

 perous peoples, where now is nothing but desert, and where even the 

 most advanced modern skill in irrigation could not support the popula- 

 tion of the old days. 



And yet all the changes alluded to above may be only the secular 

 variations in climate that we know are going on all the time. The 

 climatic changes of the west coast which will be described in this paper 

 are older than those fluctuations recorded in history, and much greater. 



The old geological theory was that the earth cooled down slowly 

 from the poles toward the equator, and that life first appeared at the 

 poles. It was further thought that in the more remote geologic ages 

 the interior heat of the earth was so great that there was little differ- 

 ence in temperature between the equator and the poles, and that, until 

 Tertiary time, there was no differentiation into climatic zones. The 

 Glacial epoch was supposed to be the culmination of this secular cooling 

 off of the earth. 



Then came the discovery of the old Tertiary fossil floras of Siberia, 

 Alaska and Greenland, with abundant forests of trees that evidently 

 lived in a temperate climate where it is now arctic. This was so remark- 

 able that geologists had to invent some extraordinary explanation for 

 the phenomenon. They rose to the occasion and invented the theory of 

 the obliquity of the poles in early Tertiary time, to account, for the 

 warm temperature under the arctic circle. This, however, did not agree 

 with the known distribution of life at that time over the rest of the 

 earth, and also the physicists declared this obliquity, or any obliquity, 

 to be a mathematical impossibility. 



Later it was discovered that there was a great glacial epoch in the 



