THE TERRACES OF SISTAN. 299
Older abandoned shorelines.—Traces of the older lake level were not found in great abundance on the southeast side of the lake, although there were enough to prove that they exist. At Lutuck the lower bluffs are capped by a narrow plain or terrace about 15 feet, possibly more, above the 15-foot beach. From this rises a second line of bluffs much more worn than any of the lower ones and well sheeted over with gravel, so that they present a slope which a horse or even a camel can ascend. At Seh-Kuheh and Sabazkim there are similar old bluffs. Those at Sabazkim are shown in the sketch (fig. 174). From either side of the central bluff
Fig. 174.—Sketch Map of the Ancient Shore features in the Bay of Sabazkim.
a wing of terrace branches off at a height of about 3o feet above the 15-foot beach. The foot of the upper terrace seems to represent the position of the lake at the time when the 25-foot beach was formed in the neighborhood of Bereng. Apparently here, as at Kuh-i-Chaku, warping took place between the last two fluvial epochs.
A comparison of the lacustrine terraces of Sistan with those of other regions described in this volume shows that in each case there were two epochs of high water preceding the present epoch of low or medium water. At Shor Kul, in Chinese Turkestan, at the playas of Khaf and of Kulberenj and at Sistan precisely the saine phenomena are repeated. In the latter case we should not expect more than two lacustrine terraces, because of the movements of the crust which have interfered with possible records of older lake levels. In the other cases, however, a greater number would be expected to agree with the number of glacial or fluvial epochs of which there is evidence in neighboring mountains or valleys. It seems probable that the interfluvial epoch preceding the formation of the first terrace was of unusual length, or of unusual character in some respect, so that traces of earlier lacustrine action were destroyed. Such a supposition is supported by the great gap which we have seen to exist at Kogneh and at Ballston between the two lower
terraces and those above them.