478 E. HUNTINGTON SOL.VR HYPOTHESIS OF CLIMATIC CHANGES 



^ Page 



The trend of opinion as to the climate of the past 526 



Progressive desiccation during historic times 527 



Climatic uniformity during historic times 528 



Climatic pulsations during historic times 529 



Trees as a climatic yardstick 521> 



Climatic pulsations according to critics of the hypothesis of progres- 

 sive desiccation 582 



Objections to the hj-pothesis of climatic changes 534 



Ancient droughts and famines 534 



The existence of deserts in ancient times — Alexander's march... 534 

 The distinction between changes of temperature and changes of 



precipitation •j.'Jfi 



Examples of large variations in rainfall accompanied by slight 



variations in temperature. 53s 



Diversity of changes of climate in different regions 530 



The shifting of climatic zones — Penck's hypothesis .'»4<» 



Possible explanations of historic changes of climate 544 



The meteorological hypothesis 544 



The volcanic hypothesis 544 



The solar hypothesis 544 



General discussion 544 



The United States .^.l 



Asia 549 



Europe 54J> 



The probability of great changes in sun-spots in the past 552 



Pettersson's sun-spot hypothesis 552 



The scarcity of early sun-siK)t data 553 



Major sun-.six»t cycles of the present time .553 



The nature of sun-spots 55.'> 



The connection between historic changes of climate and the Glacial 



period .55t; 



Complexity of post-Glacial climatic variations in the Southwest 55« 



Free's data as to old strands in the Southwest 55S 



The inclosed lakes of Asia 563 



The causes of the Glacial period 5»>~i 



General discussion 565 



The carbonic acid hypothesis 564; 



The r-yclonic solar hypothesis .■»6T 



General discussion .'87 



The double storm belt in America 56S 



The glacial storm belts of Europe 572 



The effect of the glacial storm belts on temperature and precipita- 

 tion 572 



The glacial precipitation of the Alps 574 



The distribution of loess ^7'* 



Permian gla^iation .">7^ 



General discu.<«sion 57s 



The effect of precipitation on temperature 579 



