90 THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



one place to another, and in general the conditions of Ufe must have been revolutionized. 

 In this way it is quite possible that we may be able to date and characterize some of the 

 chief epochs in early American history. 



As has already been stated, the more severe climatic variations of the present time 

 appear to be in general synchronous in the United States and Europe. This was evident 

 in the summer of 1911, when England was so dry as to be changed from a green land to a 

 brown, and the eastern United States had the hottest, driest season for a century. If 

 larger climatic variations are Mkewise synchronous in both hemispheres the chronology of 

 climatic changes which has been worked out in Asia may assist in the elucidation of the 

 unwritten history of America. In Asia each of several great dry epochs seems to have been 

 marked by great movements of the nations and by the more or less complete reorganization 

 of society in the regions which were most influenced. The first such epoch can be dimly 

 discerned about 1200 b. c. At that time the ancestors of the Greeks came into their 

 peninsula, the Hebrews entered Palestine, the Aramaeans from Arabia spread out into 

 Babylonia and all the neighboring lands, and Egypt was overwhelmed by invaders from 

 both the Libyan and Arabian deserts. The next great period of aridity apparently culmi- 

 nated in the seventh century after Christ or thereabouts. Its approach seems to have 

 been marked by the barbarian invasions of Europe and its culmination by the Mohammedan 

 outpouring from Arabia. Finally, the thu-d of the more important dry epochs came about 

 1200 A. D., when the hordes of Genghis Khan ravaged Asia from China to the Mediter- 

 ranean. Besides these more intense periods of aridity there seem to have been others of 

 minor importance, but these may here be omitted. Between the epochs of aridity periods 

 of prosperity, expansion, and growth have apparently coincided with favorable conditions 

 of climate. In studying the ruins of America we have thus far found no data which enable 

 us to correlate the climatic history of the Old World and the New. Nevertheless, we find 

 in each continent three main periods of prosperity and apparently of abundant precipi- 

 tation in the drier portions. Perhaps this may be due to an actual agreement in climatic 

 events. The ancient and widely extended farming population of the remote httle ruins 

 of our southwestern i:)lateaus may have lived in the period of moist climatic conditions of 

 which we seem to find e^ddence at the time of Christ and earlier. Their disappearance may 

 have been due to the aridity of the period which culminated in the seventh or eighth 

 centuries. Then the village* people, the Pajaritans, may have flourished in the middle 

 ages, a period moister than the present, but not so moist as the preceding propitious epoch. 

 They may have been ousted by the twofold disaster of prolonged drought and fierce invasion 

 which would have come to America about 1200 or 1300 a. d. if conditions here were like 

 those of Asia. And finally, the occupation of places like Gran Quivira by the modern Pueblo 

 Indians may be the result of propitious conditions following the dry period of the thirteenth 

 century. Such a correlation between climate and history is as yet merely a suggestive 

 hypothesis, but it may well be kept in mind in future investigations. 



SUPPLEMENTARY STATEMENT. 



Since the preceding chapter was prepared for the press there has come to hand a publication 

 bearing the title "The Physiography of the Rio Grande Valley, New Mexico, in relation to Pueblo 

 Culture," by Edgar Lee Hewett, Junius Henderson, and Wilfred William Robbins, Washmgton, 

 1913. The last thirty pages of this are devoted to an article on " Climate and Evidence of Cli- 

 matic Changes," by Junius Henderson and Wilfred W. Robbins. In this article the authors in 

 general adopt the methods set forth in " Explorations in Turkestan" and in "The Pulse of Asia." 

 Their work was apparently completed prior to the appearance in 1911 of the first of my own 

 articles on changes of chmate in the United States. Therefore, their conclusions are of the more 



