on the Central Asiatic railroad, a hundred miles east of the terminus at Krasnovodsk on the Caspian Sea, we saw two particularly interesting strands at an elevation of two hundred and fifty and one hundred and fifty feet above the Caspian. The lower occupies the position where, according to the conclusion reached above, the shores of the Scythian gulf stood in the days of Herodotus and his successors.
If we admit that such an expansion of the Caspian Sea is an historic fact, the question arises whether it can be explained without postulating a change of climate. An increase in the amount of water used for irrigation during more recent times cannot be appealed to, for it is generally admitted that the population and hence the consumption of water in the Aralo-Caspian basin was greater in ancient than in modern times. Warping of the earth's crust will not explain the matter, for granting that the position of the sea may have been altered by this means, the water-spread, or surface exposed to evaporation, would remain practically constant so long as the climate remained constant. The water-spread of ancient times, however, appears to have been very great, possibly almost double that of to-day. Changes in the course of rivers are an equally inadequate explanation, for the same reason. The Oxus and the Jaxartes are the only rivers which have been seriously suggested as possible contributors to the expansion of the Caspian Sea. Between them they furnish most of the water which balances the evaporation from the 26,000 square miles of the water-spread of the Sea of Aral. Even if they could avoid depletion by underground drainage into the basin of Aral, two hundred and twenty feet below the present level of the lake,
IIIFカラー高解像度
