国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

OASES.   3~1

As a center of trade old Anau lay at the intersection of two important routes , the route from Meshed to Khiva crossing here with the great through way from Balkh via Mery round the Caspian's southern shore.

THE BUILDING OF A TILTING DELTA.

The Anau delta is one of a group of similar fan-like plains spread out, side by side, from the mountains, and merging together into a piedmont whose slope averages perhaps i in boo. Although the history of such an area is essentially one of a varied aggradation, there is a peculiar deviation from this rule towards the margins of a Central-Asian plain, a deviation which has especially complicated the part which of any delta, subaerial or subaqueous, is necessarily most complex in manner of growth. It is only well out on the area of deposition that only

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Fig. 485.—River-cut Mounds of Millitinskaya (Timur's Gate).

deposition takes place, for most of the layers formed near the apex of radiation afterwards suffer removal to a greater distance. No permanent growth of the apex itself can take place without either a corresponding aggradation of its debouching valley's flood-plain above, or a relative sinking of the plain below. Of such a sinking we have manifold evidence, and it is the way in which the plains of Central Asia sank that wrought their marginal peculiarities. This of course is the uptilting of narrow strips of piedmont beds forming low ridges with f aultscarps facing mountainwards and back of which the strata and conformable surface slope into the basin where they are buried by later waste. Whatever the cause of sinking, these uptilted piedmonts have resulted; and, with that part of the Anau delta where the oases were, tilting appears to have been one of the controlling factors of topography, not only of the present surface but also, as we shall see, of the surface of antiquity now buried by later waste.

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