652 K. PUMPELLY EVOLUTION OF OASES AND CIVILIZATIONS 



liarly characteristic of the uppermost or iron culture of the kurgan; 

 and from this level it continued to grow upward a further 7 feet, after 

 which irrigation was introduced. Now we have archeological and strati- 

 graphical evidence that the introduction of artificial irrigation was about 

 contemporaneous with the founding of the city of Anau and the aban- 

 donment of the south kurgan. 



Our ratio, 1 to 2.5, is equivalent to a growth of 17.5 feet of culture 

 strata between the time of deposition of the iron-culture pottery in shaft 

 B and the apparently contemporaneous ending of the life of this culture 

 and the beginning of irrigation, while there are only 4 feet of iron 

 culture now standing on the top of the kurgan. The great deforma- 

 tion that this hill has suffered is evidence that it has lost a considerable 

 amount of its original height, and it is likely that the difference between 

 the 17.5 feet of iron culture required by our ratio and the 4 feet now 

 standing is a proximate measure of that wastage. I have therefore, in 

 the column of cultures, added this 13% feet to the present thickness of 

 culture strata of the south kurgan; and since the time of abandonment 

 of the north kurgan is separated from us by nearly three times as many 

 centuries as that of the south kurgan, I have added to it 30 feet to rep- 

 resent the culture strata wasted by wind and rain. 



Let us turn now to the shafts at the north kurgan. Here in shaft I, 

 200 feet west of the kurgan, we found a wall and hearths and lower- 

 culture pottery at a depth 8 feet deeper than the base of culture in the 

 kurgan. The conditions showed that the settlement was started on the 

 side of a valley which had dissected the delta-plain. Several hundred 

 feet farther west, in shaft II, we could trace the progress of refilling of 

 the valley, for, at the same level as the deep culture in shaft I, we found 

 here pottery of the lower culture. This pottery characterized the up- 

 ward growth of the strata during 8 feet. At this level the association 

 of upper-culture pottery, charcoal and bones, as well as their conditions, 

 indicate that the aggrading had ceased. 



The sediments above this pottery seem to belong to the latter ag- 

 grading, which submerged the early culture at the south kurgan. 



Change-producing Agencies 



Let us now consider the agencies that have been active in these pro- 

 cesses of cutting down and rebuilding. They form one of the most in- 

 teresting illustrations of the law of compensation in the grand cyclical 

 action of forces that have modeled the relief of the surface of our planet. 



