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Digital Archive of Toyo Bunko Rare Books

ment on the South Kurgan and the city of Anau were both founded during the
last aggrading. The arid period between the two last aggradings coincides with
the long abandonment of the South Kurgan between the copper and iron cultures,
and the previous arid period coincides with the interval between the North and
South Kurgans. Lastly, in addition to the agreement shown in the rise and
decline of civilizations, we have confirmation from the biological side in the pro-
gressive stunting of the breeds of domesticated animals, as shown by Dr. Duerst,
which, according to him and to Nehring, is due to insufficient food and to desert
conditions.

We have no direct observations as to whether the valleys are now deepening
on the zone of tilting in the present period of aridity, because under irrigation
the silts are all held up, and alluviation is artificially maintained up to the apex
of the deltas.

It would be of great interest to know whether these cycles were of proximately
equal periodicity. Unfortunately, the two critical factors in the problem, depth
and rate of valley-cutting, are wanting. Penck has shown that the last of his
four ice-epochs of the glacial period was followed by a series of lesser though
great oscillations of diminishing intensity; and it is thought that the oncoming
and passing of each glacial epoch was marked by climatic oscillations of respec-
tively increasing and decreasing intensity. Our cycles at Anau covered periods
of between 3,000 and 4,000 years' duration. Oscillations of such magnitude would
seem to belong in the order of phenomena of mundane extent and possibly of
astronomic relations. The question may be risked, I think, whether they may
not be fainter vibrations in a series, diminishing in intensity since the last of
Penck's oscillations.

The argument contained in this chapter, and represented graphically on
plate 5, is based on observed facts and on the writer's inferences drawn from these
facts. As facts of observation, we have in three neighboring sites an aggregate
of 170 feet of culture-strata of uniform character belonging to the distinctly differ-
ent cultures of five separate and successive occupations. That part of the argument
which establishes the parallelism between the physical and human history of the
region, rests upon observed parts of three periods of aggrading with two inter-
vening periods of cutting-down of the valley. The aggradings are drawn in full
lines in each case opposite that part of the culture-strata during the accumulations
of which the aggrading took place. These full lines represent, therefore, the
minimum depth of valley deepening, the observed amount and maximum height
attained by aggrading, and its duration measured in feet of contemporaneously
accumulating culture-strata. It will be observed that the essentials of this part
of the argument consist in the observed aggradings, represented by full lines, and
length of cycles. Plate 5 tells us the history of the oasis of Anau free from the
writer's inferences, but it is desirable that some things previously stated be
repeated at this point.