CULTURE SUCCESSION 649 



and which, under their peculiar civilization, lasted enough tens of cen- 

 turies for their remains to accumulate to a height of 60 feet. 



They brought with them the potter's wheel and their own technique 

 in pottery; and they had a full knowledge of the use of copper, and a 

 knowledge of lead, which for some purposes they alloyed with copper. 

 But they did not know bronze. Out of 23 objects analyzed by Professor 

 Gooch, a ring and a small implement contained under 6 per cent of tin; 

 a dagger, 1.58 per cent; another small object, 1.65 per cent. Excepting 

 these four, all the others, including two daggers, two spears, an arrow 

 point, a sickle, and a razor-shaped implement, were without a trace of 

 tin. 



All of the three cultures that I have mentioned had in common a 

 remarkable burial custom : they buried children, and only children, under 

 the floors of the houses, in a contracted position. 



This people was finally succeeded by one in a low stage of culture, to 

 judge from their coarse hand-made pottery; and they, in turn, were 

 supplanted by a people who brought in the use of iron and a different 

 pottery. 



Neither these nor the barbarians who immediately preceded them 

 buried their children in the houses. The old order of related peoples 

 and cultures was gone, and one showing wide connections was estab- 

 lished. 



After this iron culture had left the south kurgan, the city of Anau 

 was founded, and a modern system of artificial irrigation was introduced 

 soon after the beginning of our era. 



Kelation of the Cultures to Their Environment 



It is to the relation existing between these cultures and their environ- 

 ment that I beg now to call your attention. 



You have seen how, with the slow trend of climatic change toward 

 aridity, life-sustaining areas became gradually restricted to the desert- 

 bound delta oases at the mouths of streams issuing from the mountains. 

 I will now describe the manner of growth of these deltas and the rela- 

 tion of this growth to that of the culture strata,' as we call the accumu- 

 lated layers of the debris left by successive generations and by super- 

 imposed civilizations. 



The first information obtained in this direction was from the shafts 

 sunk at and near the south kurgan and shown on figure 2. We were 

 fortunate in finding in these the data for calculating the relative rates 



