tjoo The National Geographic Magazine 



From Wm. M. Davis, Carnegie Institution 



A Sand Dune Advancing Across the Desert 



It had long seemed to me that a study 

 of central Asian archeology would prob- 

 ably yield important evidence in the 

 genealogy of the great civilizations and 

 of several at least of the dominant races, 

 and that a parallel study of the traces 

 of physical changes during Quaternary 

 time might show some coincidence be- 

 tween the phases of social evolution and 

 the changes in environment ; further, 

 that it might be possible to correlate the 

 physical and human records and thus 

 furnish a contribution to the scale of 

 recent geology. 



While we have been surprised at the 

 abundance of the data in natural and 

 artificial records offered by the region 

 toward these solutions, we are impressed 

 with a realization of the intimate rela- 



tion in which this region stands to the 

 Quaternary and prehistoric history of the 

 whole continent. Physically it forms 

 part of the great interior region extend- 

 ing from the Mediterranean to Manchu- 

 ria, whose history has been one of por- 

 gressive desiccation, but in Russian 

 Turkestan the effects of this have been 

 mitigated by the snows of the lofty 

 ranges and the lower altitude of the 

 plains. 



Archeologically this region has, 

 through a long period, been a center 

 of production and commerce, connect- 

 ing the eastern, western, and southern 

 nations, and its accumulating wealth 

 has made it repeatedly the prey of in- 

 vading armies. It has been from re- 

 mote time the field of contact and con- 



