THE FLUCTUATING CLBfATE OF NORTH AIMERICA.^ 



By Ellsworth Huntinqtok, 

 [With 10 plates.] 



PART I. THE RUINS OF THE HOHOKAM. 



During his connection with the Pumpelly expedition sent out by 

 the Carnegie Institution in 1903-4 to Transcaspia and adjacent 

 regions the present author came to the conclusion that in the dry 

 regions of central Asia the climate of the past was distinctly moister 

 than that of the present. Durmg the next two years an expedition 

 by way of India to Chinese Turkestan, in company with Mr. R. L. 

 Barrett, led him to extend this conclusion over a wider area and to 

 believe that the change of climate has not progressed regularly, but 

 by pulsations. Still another expedition to Palestine, Asia Minor, 

 and Greece in 1909 on behalf of Yale University seemed to confirm 

 the pulsatory theory, and to show that the general course of history 

 for at least 3,000 years has been in harmony with the supposed 

 climatic pulsations. ]\IoreoVer, the observations of others, even of 

 men such as Beadnell, who do not believe that the climate of the 

 earth has changed in recent times, seem to indicate that north 

 Africa, on the one hand, and central Europe on the other, as well 

 as southern Europe and large parts of Asia, have also been subject to 

 climatic changes. Thus there seems good ground for the conclusion 

 that during historic times essentially synchronous climatic pulsa- 

 tions have taken place in all of the vast region of the Temperate Zone 

 from China on the east, across Asia and Europe, to the Atlantic on 

 the west. Obviously, if such pronounced and widespread changes 

 have occurred in the Eastern Hemisphere, there is a possibility that 

 changes of a similar nature may have taken place in America. 

 Accordingly when Dr. D. T. MacDougal, director of the Department 

 of Botanical Research of the Carnegie Institution of Washington, 

 invited the author to cooperate with the Desert Laboratory at 

 Tucson, Ariz., in a climatic study of the arid southwestern portion 

 of North America, the opportunity seemed too good to be neglected. 

 Three seasons, consisting of three months in the spring of 1910, 



' Reprinted, by perinlssion, abridged by the author, from The Ceograpliifiil Journul, Loudon, for Sep- 

 tember and October, 1912. * 



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