528 E. HUNTINGTON SOLAK HYPOTHESIS OF CLIMATIC CHANGES 



single instance, but it could scarcely be the case in many hundreds or 

 thousands of ruins. 



The arguments in favor of a change of climate during the last two 

 thousand years seem too strong to be ignored. Their very strength, how- 

 ever, seems to have been a source of error. A large number of people, 

 among whom I plead guilty of having been included during the earlier 

 days of my geographical work, have jumped to the conclusion that the 

 change which appears to have occurred in certain regions occurred every- 

 where, and that it consisted of a gradual desiccation. 



CLIMATIC UNIFORMITY DURIXG HISTORIC TIMES 



Other observers, quite as careful as those who believe in progressive 

 desiccation, point to evidences of aridity in past times in the very regions 

 where the others find proof of moisture. Lakes such as the Caspian Sea 

 fell to such a low level that parts of their present floors were exposed and 

 were used as sites for buildings whose ruins are still extant. Elsewhere, 

 for instance in the Tian Shan Mountains, irrigation ditches are found in 

 places where irrigation never seems to be necessar}' at present. In Syria 

 and Xorth Africa during the early centuries of the Christian era the 

 Romans showed unparalleled activity in building great aqueducts and in 

 watering land which then apparently needed water as much as it does 

 today. Evidence of this sort is abundant and is as convincing as is the 

 evidence of moister conditions in the past. It is admirably set forth, for 

 example, in the comprehensive and ably written monograph of Leiter on 

 the climate of Xorth Africa.-- The evidence cited there and elsewhere 

 has led many authors strongly to advocate the hypothesis of climatic 

 uniformity. They have done exactly as have the advocates of progressive 

 change, and have extended their conclusions over the whole world and 

 over the whole of historic times. 



CLIMATIC PULSATIOXs DURIXG HISTORIC TIMES 



The hypotheses of climatic uniformity and of progressive change both 

 seem to be based on reliable evidence. They are diametrically opposed 

 to one another, but this is apparently because the various lines of evidence 

 have not been grouped according to their dates. When this is done, it 

 appears that evidence of moist conditions is found during certain periods ; 

 for instance, four or five hundred years before Christ, at the time of 

 Christ, and 1000 A. D. The other kind of evidence, on the contrary, cul- 

 minates at other epochs, such as about 1200 B. C. and in the seventh and 



— H. Leiter : Die Frage der Klimaanderimg wahrend geschichtUcher Zeit is Xordafrlka. 

 Abhandl. K. K. Geographischen Gesellschaft. Wien, 1909. p. 143, 



