18 THE FORMING OF THE OASIS OF ANAU. 
was found to be at 20 feet below the surface of the plain, while a shaft (North 
Kurgan west shaft 1) 200 feet distant disclosed culture-strata down to a depth of 
28 feet, belonging to a part that had been overgrown by the rising alluvial growth. 
Not only was this true of the North Kurgan, but it was found that the much younger 
South Kurgan also was based 20 feet deep. On the other hand, the base of the 
younger city of Anau was found to stand only 15 feet deep. ‘The fact that two 
kurgans, between the beginnings of which the time-interval could be reckoned 
only in thousands of years, had been buried to the same depth, clearly presented a 
physiographic problem of great interest. It seemed, too, that its solution should 
aid in correlating the history of the successive cultures of the region with the course 
of natural events. / 
I decided, therefore, to attack this problem with shafts, while Dr. Schmidt 
was directing the purely archeological excavations. From the beginning the shafts 


Fig. 7.—A Pool in Bokhara. 
showed that the records left by man and those buried by nature ran parallel, and 
that a study of each was essential to a good understanding of the other. They 
showed also that much of the physical history of the region, as well as of its human 
record, could be read only underground. It was found that during the existence 
of the two kurgans there had been a succession of alluvial growths with intervening 
degradations, succeeded in the end by a considerable thickness of irrigation silts. 
There were, therefore, three kinds of growths—natural sediments, irrigation sedi- 
ments, and culture-strata. It was clearly desirable to obtain some light on the 
relative rates of these growths, for, having this, if we should be able to determine 
the rate of either one in years, it could be applied to all, including the culture-strata. 
There were sunk 24 shafts. Nine were intended to determine the thickness 
of the culture-strata and the character of the underlying natural formations. ‘Iwo 
