22 THE FORMING OF THE OASIS OF ANAU.
uppermost or pure iron culture of the kurgan, i. e., of that part of culture IV which begins 8 feet above the top of culture III, for under IV is classed an interval of 8 feet of débris of wastage during which little or no culture seems to have existed ; and from this level it continued to grow upward a further 7 feet, after which irrigation was introduced. Now we have archeological and stratigraphical evidence that the introduction of the artificial irrigation which produced these sediments was about contemporaneous with the founding of the city of Anau and the abandonment of the South Kurgan.
Our ratio, i to 2.5, is equivalent to a growth of I7,5-feet-of culture-strata between the time of deposition of the iron-culture pottery in shaft B and the
Fig. 12.—Deformation of the Walls of Ghiaur Kala during about Twelve Centuries.
apparently contemporaneous ending of the life of this culture and beginning of irrigation, while there are only 4 feet of iron culture now standing on the top of the kurgan. The great deformation 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 minimum measure of that wastage. I have, therefore, in the column of cultures, added this 13.5 feet to the present thickness of culture-strata of the South Kurgan.
Let us turn now to the record of the shafts near the North Kurgan. We have seen that while the main mass of the kurgan is based at a depth of 20 feet
Fig. 1 1. -Twelve Centuries of Deformation on Citadel of Ghiaur Kala, Merv.