REPORT OF EXECUTIVE COMMITTEE. 77 



all used for irrigating these fertile spots. Beyond them is the desert. 

 Anau is on one of these fans. 



The history of these tumuli and of the city is sharply character- 

 ized by the following four periods in the historj' of the plain or sub- 

 aerial delta : 



(i) The north tumulus when founded stood on a hill at least 7 

 feet, and probably more, above the general plain surface, its dwell- 

 ings spreading down the slopes. The plain was then increasing its 

 height, through the deposition of river sediments, and continued to 

 grow until it had buried the base of the tumulus to a depth of 2 feet. 

 By that time, or later, the north tumulus was abandoned and the 

 south tumulus founded on an elevation about 2 feet above the plain. 

 The plain continued to grow until it had buried the base of the south 

 tumulus to a depth of 14 feet. 



(2) Then followed a change of conditions, either climatic or 

 orogenic. The plain was cut down at least 19 feet. 



(3) This was followed by another change, which caused the re- 

 filling of the cutting to the amount of 8 feet, y feet of this last growth 

 having occurred after the deposition in its sediments of pieces of the thor- 

 oughly characteristic pottery of the youngest {the iron) culture of the 

 south tumiibis. 



(4) After this, irrigation began, through which the surface of 

 the plain was raised 1 5 feet higher, bringing it to its present condi- 

 tion, in which the north tumulus stands embedded to a depth of 27 

 feet, the south tumulus 22 feet, and Anau city 15 feet. 



Thus it is evident that the whole of this growth has taken place 

 since the topmost 13 feet of the j^oungest tumulus was started — 

 i. e., after the accumulation of the 123 feet of bronze and neolithic 

 culture-strata. The base of the 38 feet of culture-strata under the 

 city of Anau stands on the same level as the base of the 15 feet of 

 irrigation sediment that surrounds it. The whole of this 15 feet of 

 irrigation deposit has, therefore, grown since the founding of Anau. 



The maximum thickness of irrigation deposit in the oasis is appar- 

 ently 22 feet. It was .shown above that 15 feet of irrigation material 

 and 7 feet of natural sediment had grown up since some time after 

 the introduction of iron. Our observations show that the growth of 

 natural sediments was much slower than that of irrigation material. 

 Indeed, irrigation retains on the fields all of the silt which would 

 otherwise flow beyond the oasis. Therefore there can be little doubt 

 that irrigation in this region was introduced during the iron stage 

 of culture. 



