76 ORIGIN OF LIFE IN AMERICA 



bring about the conditions of a Glacial Epoch. On the con- 

 trary, it is evident that the opposite result would take place. 

 The conditions of a Glacial Epoch, says Professor Whitney, 

 are not to be sought for in a general diminution of tem- 

 perature. " It is true," he argues, " that the regions in which 

 the glaciers take their rise cannot be so warm that precipita - 

 tion takes the form of rain ; but the required low temperature 

 must be confined to a limited area, and be brought about by 

 local causes, and not be something in which all the other 

 portions of the earth are sharers. There must be copious 

 precipitation, which, although locally in the form of snow, 

 can in reality only be the result of a high mean temperature 

 in other regions. In short, warmth, as a phenomenon of 

 general occurrence, is more indispensably necessary than cold, 

 because the latter may always be produced, where locally 

 wanted, by increase of elevation or by the shifting of the 

 ocean currents."* 



We now know that the glaciation of Alaska during the 

 Ice Age must be regarded as an extension of the present 

 system of glaciers. They were no doubt considerably larger, 

 while glaciers also existed in the Endicott range in north- 

 western Alaska. Nevertheless, no signs of former glaciation 

 have as yet been discovered in the interior of the country. 

 The latter is now generally believed to have been entirely 

 unglaciated. If we adopted Professor Whitney's views, and 

 endeavoured to picture to ourselves the conditions of Alaska in 

 the Glacial Epoch, we must imagine the Pacific to have been 

 warmer than it is now and the climate of Alaska much milder 

 and more humid. A more luxuriant flora would, under such 

 circumstances, have been able to flourish in the interior of the 

 country, and consequently a richer and more varied fauna. 



And how much is this conception of the Glacial Epoch at 

 variance with the theories generally propounded ! I may be 

 excused, for example, for again citing Professors Chamberlin 

 and Salisbury's f words, that one of the most marvellous 

 features of the ice-dispersion during the Glacial Epoch was 



* Whitney, J. D., "Climatic Changes," p. 388. 



t Chamberlin, T. C., and E. D. Salisbury, "Geology," Vol. III. 

 pp. 332333. 



